Social behaviors ch 9

Eusocial animals

Eusocial animals are distinguished by four characteristics: -Some animals are so extremely social that we call them eusocial. Eusocial (i.e., "truly" social) -Eusocial insects pollinate plants, consume plant and animal material on a large scale, and recycle wood and organic detritus. Their dominance in the world is due in large part to the immense success of eusociality. -These Texas leaf-cutter ants (Atta texana) are one of many highly social species 1. Several adults living together in a group 2. Overlapping generations of parents and offspring living together in the same group 3. Cooperation in nest building and brood care 4. Reproductive dominance by one or a few individuals, and the presence of sterile individuals rest sterile or forced Among insects, eusocial species are limited to Hymenoptera and Isoptera, including bees, ants, wasps, and termites. Other than insects, the only two animals known to be eusocial arethe naked mole rat and the Damaraland mole rat -most individuals in a eusocial group don't mature sexually or reproduce. Instead, they specialize at tasks that include defending and foraging for the group or taking care of the subsequent offspring of their parents

Why do many people consider the licensed hunting of deer an important tool for managing the health of wild deer populations?

Hunting deer keeps large deer predator populations low. wrong Humans have already removed large predators from a large portion of the United States. Hunting causes deer to avoid low-quality areas occupied by humans. Hunting isn't generally allowed in human settlements Hunting deer reduces disease outbreaks and competition for food. do not repro more w low pop, helps not spread disease

? is a common interaction between two conspecifics that compete for a resource such as food, as when a bald eagle attacks another to steal a captured fish.

Selfishness . We would therefore expect natural selection to favor any donors that engage in either cooperation or selfishness. Spitefulness cannot be favored by natural selection under any circumstance given that both participants experience lower fitness , altruism, increases the fitness of the recipient but decreases the fitness of the donor. Explaining the evolution of altruism presents a unique challenge because it requires natural selection to favor individuals, that improve the fitness of others while reducing their own fitness.

What is the indirect fitness benefit for a donor who helps his recipient cousin produce and raise three offspring

0.125*3=0.375

The coefficient of relatedness is the probability that two individuals have inherited the same copies of a gene from a recent common ancestor. The coefficient of relatedness ranges from 0 to 1, which indicates that the compared pair is either not at all related or genetically identical, respectively. Determine the coefficient of relatedness between each pair of specified family members. Enter your answers in decimal form and do not round your answers.

1 means two individuals have inherited the same copies of a gene from a recent common ancestor. Mother and son in a diploid system: .5 Full sister and brother in a diploid system: .5 Full sister and brother in a haplodiploid system: .25 The coefficient of relatedness is the probability that copies of a particular gene are shared by relatives. Diploid parents each have two copies of each chromosome and provide one copy, or 50%, of their genetic material to their offspring. Therefore, the coefficient of relatedness between a diploid offspring and each parent is 1/2, or 0.5. Siblings also have a coefficient of relatedness of 0.5, which is derived from the probability that they will inherit the same copy of a gene. The probability can be calculated as the average of two possible extremes. At one extreme, identical twins are siblings that share all their genes, which gives them a realized coefficient of relatedness of 1. Siblings might also share none of their genes. For example, given a mother and father with two sets of genes, A‑B and C‑D, respectively, if one sibling inherits copies A and C, and the second sibling inherits copies B and D, then their realized coefficient of relatedness is 0. The average of these possibilities is (0+1)/2, or 0.5. Another way to consider the full sibling relationship in a diploid system is to calculate the sum of the probability of shared inheritance from the mother and father. Each parent passes on one of two sets of chromosomes, or 50% of their genetic material. Because each sibling has a 50% chance of receiving the same set of chromosomes from a single parent, the probability of shared inheritance from that one parent is 0.5×0.5, or 0.25. Therefore, the sum of the probability of shared inheritance from both parents is 0.25+0.25, or 0.5. In a haplodiploid system, females have two sets of chromosomes, whereas males have only one set. Both female and male offspring inherit one set of genes from their mother, but only females inherit a second set of genes from their father. Although female siblings have a 50% chance of inheriting the same copy of a gene from their mother, they have a 100%chance of inheriting the same copy of a gene from their father. Therefore, full female siblings have the probability of sharing 1/4 of their genetic material through their mother and 1/2 of their genetic material through their father. Full female siblings have a 75% probability of genetic similarity and a coefficient of relatedness of 0.75. The coefficient of relatedness for a full sister and brother in a haplodiploid system is calculated similarly. The mother contributes one set of chromosomes to male and female offspring, but the father contributes one set only to female offspring. Therefore, a full sister and brother have a 1/4 probability of sharing their genetic material through the mother and zero probability of sharing any genetic material through the father. A sister's coefficient of relatedness with her male sibling is thus 0.25.

In a newly discovered species of tropical wasp, males have two options for passing along their genes to the next generation. One option is for the males to breed with females, in which case males produce an average of 4.3 offspring, which will grow up to reproduce themselves. Alternatively, a male can help his brothers and sisters mate and raise their offspring. In this strategy, a male has an average of two siblings that survive to reproductive maturity, and with his help, each sibling will produce an average of 4.6 offspring that will survive to reproduce. The male should opt for a(n) _____ mating strategy, as it will increase his inclusive fitness by _____.

4.3=dir ben->selfish strategy 4.6*0.5*2=9.2-4.3=4.9

Group benefits: predators

A group may be able to fend off predators better than an individual. BUT ALSO ATRACT PREDATORS -For example, when a muskox herd is threatened by predators such as wolves, the adults come together in a defensive circle, with their heads and horns facing out, while the young calves are positioned in the middle of the circle for safety More individuals watching for predators allows each individual tospend less time watching, and more time feeding TOTAL TIME WATCHING UP, this is Dilution effect: the reduced, or diluted, probability of predation to asingle animal when it is in a group Example:As flock size of Europeangoldfinches increases, the totalamount of time the group spendswatching for predators increases.The individual amount of time anindividual spends watchingdecreases TOTAL WATCHING INCREASE, INDIV WATCH DECREASES -goldfinch (Carduelis carduelis), a small bird that feeds on the seed heads of plants in open fields and hedgerows. -The total number of head raises conducted by the group increases with flock size -As flock size increases, however, each individual can raise its head less frequently, -when an INDIVIDUAL goldfinch spends less time looking for predators, it can husk a seed much faster and therefore consume seeds more quickly. he dilution effect is an important benefit of large groups such as herds of mammals, flocks of birds, and schools of fish. predator has many prey choices, so an individual living in such a group has a lower probability of being caught meerkats (Suricata suricatta), multiple individuals are on the lookout for predators and they make an alarm call when a predator is spotted (Figure 9.2). Moreover, their alarm call can specify whether the predator is on the ground or in the air, MEERKAT=MORE EYES AND ALARM CALLS FOR SPOT PREDATORS only indiv head raise and seed husking time decrease -Benefits and costs of social foraging and optimal flock size in goldfinches

Mole rats, case where haplodiploidy not needed)

A single queen and several kings are responsible for all reproduction. -only two are known to be eusocial: the naked mole rat and the Damaraland mole rat. These rodents live in underground tunnels in African grasslands in colonies of up to 200 individuals. males are diploid but workers forego repro in favor of caring for colonies , can reproduce but beaten into submission by Dom female offfpsinr g, increaseign stress in other team -beating moles even when adults into submission . In naked mole rats, a single queen and several kings are responsible for all the reproduction in the colony, and all individuals are diploid -Current research suggests that the subordinate males and females do not BOTH forgo reproduction willingly. Instead, the dominant female harasses them, raising stress so repro workers not wanting to breed All individuals are diploid, but workers forego reproduction in favor ofcaring for younger siblings and the colony. Research suggests offspring arenot willingly subordinate. Workers beaten by dom female offspring The dominant female harassesoffspring, which increases stress, REDUCES levels of SEX hormones, and makes them less motivated to breed -evoles even if not huge r value, but if high costs leaving nest

group defense example

Adult muskox, like these from Victoria Island, Canada, form an outward-facing circle and place the calves inside the circle, where they are safe from approaching predators

Why altruism exists

Altruism does not lead to direct fitness, which is the fitness anindividual gains by passing on copies of its genes to its offspring. random crime=not seen in natural world Direct fitness is the fitness that an individual gains by passing on copies of its OWN genes to its offspring.-->results in dir selection We would expect selfish individuals to prevail over altruistic individuals because selfishness directly increases the fitness of the donor, whereas altruism does not gain fitness thru helping relatives it shares genes with As a result, we would expect selfishness (only donor increased fitness) to prevail over altruism, yet altruism has evolved in many species. DUE TO cooperation benefit both parties, direct benefits associated to self interest, even going in group Indirect fitness: the fitness than an individual gains by helpingrelatives (with which it shares genes through a common ancestor)pass on copies of their genes. Selection based on inclusive fitness: includes both effects but when indiv help KiN more than non-kin Because you and your relative share some genes, due to sharing a common ancestor, when you help a relative improve its fitness, you are indirectly passing on more copies of your genes, which gives you indirect fitness. The key to understanding the evolution of altruism is to consider an individual's inclusive fitness, which is the sum of its direct fitness and indirect fitness -colony odor in social insects will help if smelling, derived from food and enviro Inclusive fitness: the sum of direct fitness and indirect fitness. Direct selection: selection that favors direct fitness., CHOOSING TO LEAVE GROUP, AND PASS ON OWN GENES Indirect selection (kin selection): selection favoring indirect fitness Social interaction entails conflict seen bc of interspecific competition for food and space bw same species, direct benefits associated based on SELF interest based on flock, self interest is what ur doing, go in flock or herd based on indiv protection and self interest for that nothing else than our own self centered belief When considering how selection operates, we say that direct fitness is favored by direct selection. Indirect fitness through relatives is favored by indirect selection, also known as kin selection.

Mating An extreme example of socializing for mating benefits is A ?

An extreme example of socializing for mating benefits occurs when animals aggregate in large groups to attract members of the opposite sex by making calls or displaying in ways that capture the attention of potential mates. The location of the aggregation, known as a lek, is used only for displaying; the site has no other value. A LEK For example, males of the ruff (Philomachus pugnax)—a medium-sized wading bird that lives in northern Europe and Asia—come together at a lek and participate in mating displays to attract females. GIANT MATING DISPLAY PLACE=LEK ruff leks to determine whether lek size affected ruff mating. As you can see in Figure 9.4a, males in larger leks were more successful at attracting females. which confirms that forming social groups for mating provides fitness benefits to the male bird we expect natural selection to favor the evolution of group sizes that balance the costs and benefits for each species. A nice example of optimal group size can be found in yellow baboons, 50‒75 individuals have the lowest levels of stress, FROM FECES HORMONES Medium-size groups have the lowest stress levels because they travel less than either small or large groups and experience lower competition. Large groups must travel farther to find food due to the large number of mouths to feed, they spend more of their energy for this traveling, In contrast, small groups must travel farther because they get pushed out of foraging areas by larger, more dominant groups. The smaller groups may also experience a higher risk of being attacked by predators. BOTH TRAVEL FURHTER, BUT LARGER=MORE FOOD STRESS

Which scenario illustrates the dilution effect?

An individual sardine has a lower predation risk while swimming in a large group.

Researchers wanted to know if living in schools provides minnows protection from predators. The researchers placed different numbers of minnows into separate aquaria. The researchers then counted how many times per minute predatory fish approached the schools. The researchers calculated and plotted the sample means and standard deviations for predator approaches per minute for each school size.

As the size of minnow schools increases, the number of times a predator approaches declines. Predators approach schools of 3 minnows 0.7 times more per minute than schools of 20 minnows. The same pattern holds for the intermediate school sizes. That means living in larger schools provides minnows more protection from predators than living in smaller schools. Living in larger schools provides minnows more protection from predators than living in smaller schools.

Suppose a goat farmer wants to use artificial selection to breed goats for increased milk production in the most cost‑effective way possible. What strategies would be most effective for the goat farmer to use?

Breed offspring from the herd with the highest milk production. and Have goats live in social herds. NOT Breed the females with highest milk production. Traditionally, artificial selection has been used to target desirable traits; however, some recent studies have shown that group dynamics play an important role in trait manifestation. Moving animals to new locations can cause unnecessary stress on animals and be costly in terms of relocation and additional housing expenses. At least one of the strategies you have chosen is incorrect. Traditionally, artificial selection has been used to target desirable traits; however, some recent studies have shown that group dynamics play an important role in trait manifestation. Moving animals to new locations can cause unnecessary stress on animals and be costly in terms of relocation and additional housing expenses. Recent studies regarding artificial selection have revealed that group selection can lead to the most cost‑effective boost in overall production of domesticated animals. Researchers have begun to show that social interactions play an important role in animal survival, and that favorable social interactions can enhance overall health and reproductive qualities. By selecting offspring from the group with the highest average value for a target trait, farmers enhance selection for good group dynamics as well as the target trait. Selection for good group dynamics indirectly boosts the target trait through effects of overall health. For example, artificial selection for milk production in goats should occur better if conducted by selecting for a high‑producing herd, rather than a high‑producing individual. Traditionally, artificial selection has focused upon the individual as a method to enhance measurable, heritable traits. However, such selection can be overwhelmed by the negative health effects that are incurred by animals living in crowded conditions. Penning and breeding animals in different locations does not affect the heritability or quality of target traits.

For instance, when one lion helps another kill a gazelle and both feed from the kill, both individuals experience a fitness benefit.

COOPERATION, ONE SOCIAL INTERACTION

Ants, bees, wasps

Caste: individuals within a social group sharing a specialized form ofbehavior. queen mate ONCE w mult drones, store sperm and daughters from fertilized, nonrepro sterile female workers get food and male usually mating adn then die after w one drone -caring for sis more benefit than offspring itself, r is .75 b/w sisters -why broods favor females 3:1 in a,b,w colony --entire sterile castes, Because nonreproductive individuals are specialized for these tasks(defend, forage, care for other siblings), they are known as sterile castes. -worker honeybees are a caste that works for the hive but typically do not reproduce. Similarly, the workers of the leaf-cutter ants represent a variety of castes that do different jobs but do not reproduce -lack any direct fitness w no direct repro output Queen: the dominant, egg-laying female in eusocial insect societies;typically mate once during their lives. Mate once w multiple drones flying around and store that Soerm, lay unfert eggs for male and females are fertilized eggs Sons are made by laying unfertilized eggs and daughters are made bylaying fertilized eggs (i.e., a haplodiploid system). Haplodiploid: a sex-determination system in which one sex is haploidand other sex is diploid. Nonreproductive progeny of a queen gather food and care fordeveloping brothers and sisters Societies include sterile,female workers;reproductive drones; andfuture queens. Drone go out with probs another queen, mate and die Daughters are diploid andare produced when aqueen's haploid gamete isfertilized by a drone's haploid gamete. drones go and die after mating Drones (i.e., sons) are haploid and are producedwhen a queen's gamete remains unfertilized. Queen develop a royal jelly -sterile worker female or a fertile female is determined by the length of time the larva is fed royal jelly. As a result, the worker caste represents an arrested stage in the development of reproductive females; they stop developing before sexual maturity. -As we will see, this sex-determination system helps to favor the evolution of eusociality Haplodiploidy is important to the evolution of eusocial animals because it creates strong asymmetries in coefficients of relatedness.

Why might selfish behaviors be less favored when animals interact with closely related family members?

Closely related individuals share genes and can indirectly increase each others fitness through successful reproduction. An individual gains direct fitness by passing copies of its genes to its own offspring. An individual also receives indirect fitness when its relatives produce fertile offspring. The relatives pass on some of the genes they share with the individual. The sum of an individual's direct and indirect fitness is the individual's inclusive fitness. Close relatives that are harmed by an individual's selfish acts may produce fewer fertile offspring. The selfish individual reduces its indirect fitness if its relatives produce fewer offspring. Acting selfishly toward a relative may enable an individual to produce more offspring of its own, but the individual risks reducing its inclusive fitness. Even if the relative does not retaliate for the selfish behavior, the selfish individual may lose indirect fitness by harming its relatives. The effects of altruism are opposite to the effects of selfishness. Altruistic behaviors increase the fitness of relatives at the expense of the altruistic individual.

What C:B ratio for altruistic behavior must be exceeded for natural selection to favor the evolution of altruism between the donor individuals and their half siblings?

Consider that an altruistic behavior will evolve whenever the C:B ratio is less than the coefficient of relatedness between the donor and recipient. small cost, small C/B ratio=relatednes larger 0.25

ALTRUISM WEIRD because it does not lead to an increase in ? fitness. When considering how selection FOR ALTRUISM operates, we say that direct fitness is favored by direct selection. Indirect fitness through relatives is favored by ? selection, also known as ? selection.

DIRECT , gains by passing on copies of its genes to its offspring. NOT DIRECTLY PASSING OFF OWN GENES We would expect selfish individuals to prevail over altruistic individuals because selfishness directly increases the fitness of the donor, whereas altruism does not For example, some of the most extreme cases of altruism occur in species that live together in very large groups, such as leaf-cutter ants and honeybees, in which workers forgo personal reproduction to rear the offspring of the dominant female We can explain altruistic behavior by looking beyond direct fitness. When an individual has an altruistic interaction with a relative, it increases the fitness of the relative. when you help a relative improve its fitness, you are indirectly passing on more copies of your genes, which gives you indirect fitness. INDRECT SELECTION TO HELP GENES AND PASS ON THESE GENES FROM RELATIVES , AKA KIN SELEC indirect or kin selection occurs because an individual and its relatives carry copies of some of the same genes inherited from a recent common ancestor. The probability that copies of a particular gene are shared by relatives is known as the coefficient of relatedness its value for diploid organisms depends on the degree of relatedness between two individuals. 0.5 because a parent has two sets of genes but gives only one set to its offspring. focal individual and its siblings, we see that these two individuals have a 0.5 probability of receiving copies of the same gene from a parent. In the case of two cousins, the probability drops to 0.125 (one in eight) of inheriting copies of the same gene from one of their grandparents, which are their closest shared ancestors.

? in this ant society are the workers, and the division of labor among the workers is amazingly complex. c, nearly 30 leaf cutter ant jobs

Daughters workers The largest workers, the majors, can be 200 times more massive than the smallest workers, the minims.

A population of territorial mammals experiences an increase in population density. Why might individuals in the population give up defending their territories?

Defending territories is too costly against the greater number of conspecifics. As population density increases, territory defense may become too costly if individuals cannot effectively defend their territories against surrounding conspecifics. In general, individuals are territorial as long as the benefits outweigh the costs. However, if individuals cannot successfully defend their territories or if the resources are not worth fighting for, individuals may give up defending those territories. In general, individuals that maintain a high-quality territory or that display the highest fitness are attractive to mates, not individuals that share their resources. If individuals give up defending their own territories, they may have to travel farther to find food because of the increase in competition. Individuals do not give up defending their territories as the population density increases because they are less likely to be noticed by predators. However, individuals might give up their territories, which assure access to mates, nesting sites, and resources, when the costs are too high for the benefits, such as occurs with increasing competition from conspecifics.

Dominance Hierarchy

Dominance hierarchies1Dominance hierarchy: a social ranking among individuals in a group (when group favored over territory defending) ,typically determined through contests such as fighting or othercontests of strength or skill, all us defending room w weapons , govt dominance certain have power over others not one or two defending, living in a hierarchy established Occurs when defending a territory is impractical; such as whenconspecific density is high and it is not possible to defend against allof them so create hierarchy thru fighting them.Once a hierarchy is established, contests are resolved quickly in favorof the first-ranked member what if we all tried to use weapons to defend a territory First-ranked members dominate all; second-rankedmembersdominate all but first-ranked, and so on Like president hierarchy Linnaeus names species after where goose came from Canada not Canadian goose always Canada goose

Types of Social Interactions

Donor(sender): the individual who directs a behavior toward another individual as part of a social interaction.donor=director of behavior Recipient(receiver): the individual who receives the behavior of a donor in asocial interaction. Every interaction between two individuals has the potential to affectthe fitness of both individuals, either in a positive or negative way cooperation : when the donor and the recipient of a social behaviorboth experience increased fitness from an interaction (e.g., when aherd of lions kill prey) all lions benefit? Selfishness: when the donor of a social behavior experiencesincreased fitness and the recipient experiences decreased fitness(e.g., competition for food) taking food , food). Spitefulness: when a social interaction reduces the fitness of both donor and recipient (does not occur in natural populations), random crime spiteful not seen in natural world such as if spp has rabies -Spitefulness cannot be favored by natural selection under any circumstance given that both participants experience lower fitness. Altruism: a social interaction thatincreases recipient fitness and decreasesthe fitness of the donor. -When the attacked individual responds—by standing its ground or by fleeing—it becomes the donor of this subsequent behavior -when one lion helps another kill a gazelle and both feed from the kill, both individuals experience a fitness benefit. -We would therefore expect natural selection to favor any donors that engage in either cooperation or selfishness -e it requires natural selection to favor individuals that improve the fitness of others while reducing their own fitness

Researchers are studying the social interactions of a group of birds belonging to a newly discovered bird species. The researchers observe that the males congregate in leks in order to attract female mates. Within the leks, the males make courtship displays, either on their own or with another male. When the males display as a pair, only the dominant male in the pair ends up mating. To determine whether subordinate males who display in a pair have a higher inclusive fitness than males who display on their own, the researchers collect several pieces of information. First, there are only full brothers in the group, no half brothers or cousins. Second, subordinate males who display in a pair produce zero offspring, while the dominant males in a pair produce an average of 6.5 offspring. Third, males who display on their own produce an average of 1.5 offspring. Therefore, the researchers conclude the indirect fitness benefit to the subordinate male is _____ and the cost-benefit ratio of helping brothers reproduce equals _____.

First, there are only full brothers in the group=0.5 B=6.5, C=1.5 indir ben=0.5*6.5=3.25, 6.5 males prod by Dom male is not the benefit, it's the indirect benefit C/B=1.5/3,25=.23 3.25; 0.46-->take 3.5 as B , use indirect B

You are studying the costs and benefits of living in different size groups of crows. You observe several groups of crows at their feeding sites and record the number of individuals in the group, the proportion of time each individual spends feeding (as opposed to watching for predators), and the number of calories each individual acquires from feeding each day, in the following table: If the amount of food each individual gets at a site equals the proportion of time each individual spends feeding at a site times the number of calories each individual acquires from the site per day, which group size allows each crow to obtain the most food per day?

For each group size, try computing the amount of food each individual gets at a site by using the following equation: Amount of food = (proportion of time spent feeding per crow) × (calories obtained by crow per day) just two columns .24*112=26.88 .33*133=43.89 .42*154=64.68->group size 3 for most cals .54*117=63.18 .66*95=62.7 3 crows dif group size look at indivs in group (number of them), indiv feed time, cals acquired each day group with most food per day, per capital calorie benefit

9.4 Social interactions also exist in plants

For example, bacteria and protists can sense the presence of individuals of the SAME SPECIES, often through chemical secretions, and react in "friendly" or "aggressive" ways. chemical of microorganisms or protists to sense conspecifics free-living slime molds respond to others when they aggregate to form large fruiting bodies resemble communication in animals Protists are a taxonomically inhomogeneous group of mostly unicellular eukaryotic microorganisms.

Which statement about the benefits and costs of living in groups is FALSE?

Groups are more likely to find rare food resources but may have to spend more time and energy moving among food patches. Individuals in groups are less likely to become prey because of the dilution effect but are more likely to be spotted by predators than if they were alone. Individuals spend less time searching for predators and more time foraging in a particular food patch., nah should be optimal foraging size?

Group costs, PREDATORS

Groups of animals are more conspicuous to predators. -it is easier for a predator to spot a herd of antelopes than an individual antelope. Given the propensity of antelopes to live in herds, this cost of being detected is outweighed by the benefits of the dilution effect ANTELOPE GROUP AGONY The risk of parasites increases in groups; high densities can increase the rate at which diseases spread. Risk of disease spread is particularly problematic in aquaculture or livestock operations, where animals are kept at high densities. parasite in aquaculture livestock w high density Example: Tropical fish that live in higher densities on reefs that are not fished (i.e., protected) also have more parasites. As shown in Figure 9.5, they found that fish on the protected reef were infested with a higher number of parasite species than the same species living in a coral reef that was unprotected and fished. (fished by people so lower fish density, less parasites) -increased numbers of individuals socializing in an area pay the price of increased parasite loads. fish living in the protected reef frequently carried higher numbers of each species of parasite. aquaculture operations, which farm aquatic species for human consumption., a single infected individual can rapidly spread parasites—especially bacteria, Such infections can result in millions of dollars in lost income to aquaculture operations. breed resistant orgs in aquaculture -When there is a steady, easily available source of food, deer form large aggregations around the food. This aggregating behavior makes it more likely that the animals will experience outbreaks of parasites don't feed deer for parasite outbreak -Similar concerns exist for livestock operations in which animals are raised under very high densities. In this situation, diseases can even jump to native wildlife populations with extreme effects for such viral diseases as rinderpest, avian influenza, and West Nile virus. -For example, the disease known as eastern equine encephalitis (EEE) is a virus that can occur in unvaccinated horses. Occasionally, however, a mosquito bites an infected/(was unvaccinated) horse and then after from infected horse subsequently bites a person, inadvertently allowing the EEE virus to jump from horses to humans

Relatedness in bees

Haplodiploidy is important to the evolution of eusocial animals because it creates strong asymmetries in coefficients of relatedness. The queen has the same genetic relationship to sons as she has to daughters (r = 0.50), so she can be relatively indifferent to the sex of her reproductive offspring If a queen has mated with a single drone, then all females have the same set of genes from their haploid father and they have a 50 percent probability of sharing the same genes from their mothe R between mothers anddaughters = 0.5 r between daughters = 0.75 , share father drone genes and likely mother's genes (.5 of mother's geneS) -This causes females to be more closely related to each other than is typical in a diploid mating system r between brothers andsisters = 0.25-->only share half genes from mom based on prob her brothers are haploid, so the brothers receive no genes from the drone, but they have a 50 percent probability of sharing the same genes from their mother. Since relatednessbetween daughters isgreater than betweenmothers and daughters,caring for a sisterprovides more benefitthan caring for offspring R between bro and sis lower than r between daughters, benefits female to take care of sisters instead of brothers So female to male reproductive individuals favor females 3:1 in broods of reproductive individuals bc take care of sisters? For example, a female worker that raises a fertile sister receives the fitness benefit of that individual multiplied by the coefficient of relatedness (r = 0.75). B*r for sister When a female raises her own offspring, it receives the same fitness benefit multiplied by the coefficient of relatedness between a mother and daughter (r = 0.50) . Thus, cooperation is likely to be favored more in all-female castes than among male castes or, especially, among mixed castes. This may explain why workers in hymenopteran societies are all female. workers will cooperate workers help each other bc high relatedness , so eusocial castes will help for indirect fitness -workers are three times more closely related to their sisters than to their brothers may also explain why broods of reproductive individuals usually favor females, by about three to one on a weight basis io. When a female worker can help to rear more female than male reproductive individuals, her own INCLUSIVE fitness may actually be higher ur inclusive fitness benefited more when sharing more genes w organism ur helping

In many species of animals, group living provides the benefit of having multiple individuals looking out for predators, such as these meerkats in South Africa. goldfinch head raises

Having many eyes searching for predators allows an individual animal to spend less time watching for predators. Consider the case of the European goldfinch (Carduelis carduelis), a small bird that feeds on the seed heads of plants in open fields and hedgerows. as you can see in Figure 9.3a, the larger the group, the more eyes are on the lookout for predators. As flock size increases, however, each individual can raise its head less frequently, as shown in Figure 9.3b. Because each individual spends less time looking for predators, it can spend more time feeding. a decrease in the time required to husk a seed.->faster seed consumption Furthermore, animals may find food easily but have difficulty in capturing and killing it when they are alone a lone lion female has a low probability of capturing and killing a zebra because a zebra is large and can defend itself well against a single lion.

You are comparing the indirect fitness benefits worker bees obtain in five colonies, A through E. Within each colony, all offspring were produced from one queen from the respective colony and one drone with whom the queen mated. You select one representative female worker from each colony and count all of her brothers and sisters. Using the following table, you record your data:

In which of these colonies would the female worker you selected obtain the highest indirect fitness? colony E had lowest ratio bro to sis

Which of these statements about group size in yellow baboons CANNOT be inferred from these graphs of group size versus distances travelled in search of food and of stress hormones?

Individuals in intermediate groups avoid the costs of group living. annto infer costs avoided

MORE COSTS , FOOD SHARING

Larger groups are better able to locate food, but that food must be shared among all members. Example: Large flocks of the European goldfinch consume seeds in an area much faster than small flocks. Large flocks have to spend more time flying between patches of seeds. Each bird has to spend more time and energy looking for food. LARGE CONSUME FASTER, MORE TIME FOR EACH BIRD FLYING TO OTHER AREAS OF SEEDS FOR FOOD Need to share eggs and milk and stuff larger flocks run out of food faster and must spend extra time and energy flying to find new patches of food. -cost/ben of groups depend on ecological conds living in Assuming a genetic component for such social behavior, we expect natural selection to favor the evolution of group sizes that balance the costs and benefits for each species. A nice example of optimal group -While baboon groups can range from 20 to 100 individuals, medium-size groups with 50‒75 individuals have the lowest levels of stress, which is assessed by hormone levels found in the baboon feces -Medium-size groups have the lowest stress levels because they travel less than either small or large groups and experience lower competition. -Large groups must travel farther to find food due to the large number of mouths to feed, they spend more of their ENERGY for this TRAVELING, and they experience MORE increased STRESS from increased competition for food -In contrast, small groups ALSO must travel farther because they get pushed out of foraging areas by larger, The smaller groups may also experience a higher risk of being attacked by predators THUS COMP AND TRAVEL STRESSORS MAKE MIDDLE SIZE GROUP BEST -Groups of intermediate size have the lowest levels of stress and travel the shortest distances in search of food

intro Leaf-cutter ants are extraordinary farmers

Living in colonies of several million individuals, these ants leave the colony each day to harvest leaves from the surrounding forest Using their sharp jaws, they slice through leaves to cut off pieces that are many times larger than their bodies cut large leaf slice Back at the nest, the ants consume the sap in the leaves, but they do not eat the leaves. Instead, they use the leaves to grow a specialized species of fungus that they consume., use leaves for fungus Like honeybees, the leaf-cutter ants form enormous societies of cooperating individuals

Group costs: aggression intragroup

Living in groups can lead to aggression among members. Example: Chickens are well-known for fighting when raised under crowded conditions. When one chicken receives an INJURY that causes a SPOT of blood on its feathers, other chickens will peck at the spot, causing more injury, more spots of blood on other chickens, and more group fighting. penthouse bloodshed, peck at spot of blood and start all pecking each other Allowing only BEST-performing social GROUPS (i.e., those that exhibit LESS fighting) selects for chickens that behave better in groups and that have a greater lifetime egg production. GREAT LIFETIME EGG PROD Breed only most DOCILE chickens GREATER LIFETIME PRODUCTION

Group benefits: food

Many individuals searching for food may be able to find rare foodmore easily -many more sets of eyes that might be able to find food when it is rare. w more searching for food Probability of prey capture may increase in a group. -. Furthermore, animals may find food easily but have difficulty in capturing and killing it when they are alone. In the case of lions, for example, a lone female has a low probability of capturing and killing a zebra -hunt in groups, the probability of capturing a zebra goes up dramatically. -large groups to attract members of the opposite sex by making calls or displaying in ways that capture the attention of potential mates. The location of the aggregation, known as a lek, is used only for displaying; leks in locations fems may need to be as well -the site has no other value. lek only where group for mating displays Being social makes it easier to find potential mates because largegroups attract the attention of females Lek: the location of an animal aggregation to put on a display to attract the opposite sex. Example: Larger leks of ruffs (a wading bird) attract more females, resulting in an increased percentage of successful male copulations. -males in larger leks were more successful at attracting females, attracting means copulations forming social groups for mating provides fitness benefits to the male birds. -Among displaying ruff males, those displaying to females in larger groups (a) are more likely to attract females and (b) have a higher probability of successfully copulating.

For baboons, what group size is most advantageous and why?

Medium groups are best for baboons because they travel the shortest distances to find food and have the lowest levels of stress.

Select the statements of evidence that a haplodiploid sex‑determination system is not required for the evolution of eusociality.

Naked mole rat colonies are dominated by a queen and several kings who produce diploid male and female offspring. and Termite colonies are dominated by a queen and king who produce diploid male and female offspring. Prairie dog colonies are dominated by an alpha female and alpha male who produce diploid male and female offspring. At least one of the statements you selected does not show that haplodiploidy is not required for eusociality to evolve. Hymenopterans operate under a haplodiploid system. The two known species of mammals that are eusocial both live only in Africa. Eusociality is a hierarchical organization of a family group that is dominated by a reproductive female, or queen, and one or more reproductive males, or kings. The family group, or colony, includes sterile castes, or offspring who perform specified roles within the colony, such as foraging, defending, or nursing. The haplodiploid sex-determination system seems to favor the evolution of eusociality but is not required for eusociality to evolve. Some insects, including TERMITES, have evolved eusocial behavior but have a diploid system of reproduction. Two species of mammals, the naked mole rat and the Damaraland mole rat, have also evolved eusociality under a diploid system. Hymenopterans, including ants, bees, and wasps, are the best-studied eusocial insects, but they have a haplodiploid sex-determination system. Prairie dog colonies produce diploid male and female offspring, but they are not eusocial animals, as they are not dominated by a reproductive pair and do not operate with a sterile caste system. EVIDENCE IS REG DIPLOID SYSTEM AND EUSOCIALITY, DOM BY REPRO PARI AND STERILE (OR SOME IN CASTE) STERILE

If an individual cannot reproduce, should it help its brother produce TWO offspring, its grandmother produce three offspring, its uncle produce four offspring, its cousin produce eight offspring, or its niece produce five offspring?

SHOUDL MULT R RELATEDNESS by benefit look at B * r, no cost of dir fit brother:2*0.5=1 0.25*(3)=0.75 4*0.25=1 0.25*5=highest cousin=.125*8=1 It should help its niece produce five offspring

Identify how removing the cats from Macquarie Island affected the island's ecosystem.

Predation on the islands' birds decreased, preventing further population drops and extinctions. The rabbit population increased tenfold, leading to the consumption of most of the island's plants. cats->birds rabbits->native veg oops virus->more veg--> cats->veg and birds->birds extinct, cats wiped out->rabbits rebound->veg->all gone Macquarie Island is unused by humans and harbors only native animals through the 1700s. Seal hunters introduce house CATS FIRST, which prey in part upon endemic seabirds. PREY ON BIRDS Seal hunters introduce European THEN RABBITS, which consume native vegetation. The abundance of plant species palatable to rabbits significantly decreases. RABBIT EAT PLANT NOT BIRD To control rabbit populations, scientists introduce rabbit FLEA VECTORS that carry the Myxoma virus. Island vegetation recovers slightly and cats exhibit prey‑switching. FROM BIRD TO VEG? Increased cat predation devastates bird populations and causes at least TWO BIRD extinctions. Scientists and government officials eradicate cats from the island. Without cats, the rabbit populations rebound and the island's vegetation decreases again. RABBITS LACKED VEG? A concerted effort eradicates all non‑native mammals from the island. NO MORE KITTY OR RABIT

COSTS OF LIVING IN GROUPS

Predation(OUTWEIGHED BY DILUTION IF IN GROUPS), and parasitism it is easier for a predator to spot a herd of antelopes than an individual antelope. Given the propensity of antelopes to live in herds, this cost of being detected is outweighed by the benefits of the dilution effect more eyes to detect approaching predators In addition, fish living in the protected reef (FROM FISHING) frequently carried higher numbers of each species AND NUMBER of parasite. High population density can increase the rate at which disease spreads and can lead to epidemics The increased cost of parasites is also readily observed in modern aquaculture operations, which farm aquatic species for human consumption. Increased transmission of parasites in high-density groups is also the reason that most state wildlife agencies discourage people from feeding wild animals such as deer. When there is a steady, easily available source of food, deer form large aggregations around the food In this situation, diseases can even jump to native wildlife populations-->livestock operations in which animals are raised under very high densities Another major cost of living in groups is competition for food(EACH INDIV BIRD MORE TIME LOOKING FOR FOOD). While larger groups are better at locating food, the food must then be shared among all the individuals Larger flocks consume the seeds in an area much faster than small flocks do, so larger flocks have to spend more time flying between patches of seeds. This causes each bird to spend more time and energy looking for food.

SNAPPING SHRIMP

Rather surprisingly, there is only one group of animals in the ocean that is eusocial. The snapping shrimps (Synalpheus spp.), a group of tiny shrimp that live on coral reefs, consists of 40 species, of which 8 are eusocial These cooperative breeding societies include either a single queen or multiple queens, depending on the species, and many nonbreeding helpers -On the reefs, food is relatively scarce and the defense of the scarce food requires a large number of shrimp to defend it, In some species, the queen has an especially large claw that it uses to fight any subordinate females in the group that try to breed. In other species, the subordinates do not breed as long as the queen is present, -, even if they do not come into contact with the queen. In this latter case, the queen may be emitting a chemical that causes the subordinates to not attempt breedin -Similar to the mole rats, the subordinate snapping shrimps likely have more fitness to gain by helping to defend the group's territory

Classify the benefits to individual birds as a result of living in a large or small flock.

Small flock: less conspicuous to predators, less food comp, lower disease transmission , lower predator attack rate Large flock: more feed ops , finding infreq or hidden food , access to gen diverse mates Large flocks receive a variety of benefits because many individuals contribute to the survival of the group. Individuals share the responsibility of watching for predators, which reduces predation risk, reduces the amount of time spent monitoring for danger, increases the opportunities to forage and feed, and enables the group to collectively locate infrequent or hidden sources of food. In addition, large flocks reduce predation risk to the individual through the dilution effect, which means that the probability that any particular individual will be attacked decreases with increasing flock size. Large flocks also offer access to greater genetic diversity in potential mating opportunities. Although individuals in small flocks spend more time watching for predators, small flocks tend to be less conspicuous. Small flock size also means fewer birds compete for food, and food resources are less rapidly depleted. Parasite and disease transmission rates can increase with group size and density; therefore, small flocks tend to have lower rates of parasite infestation and disease than large flocks.

Researchers wanted to know if living in schools protects minnows from predators. The researchers placed different numbers of minnows into separate aquaria. Then, the researchers counted how many times per minute predatory fish approached the schools. Calculate the sample means, 𝑥¯, and sample standard deviations, 𝑠, for the number of times per minute a predator approached each school size. Round 𝑥¯ to one decimal place. Round 𝑠 to two decimal places.

Standard deviation is the square root of the variance. Variance is the sum of the squared differences between the mean and each data point divided by 𝑛−1

You are studying the genetics and reproductive biology of a bee colony when you make a surprising discovery: The queen is producing diploid male offspring from the father's sperm instead of the normal haploid drones that she would produce via parthenogenesis. The males produced by this anomalous mating are functionally equivalent to normal drones and can produce viable offspring. How would you expect this single change to alter the social interactions in the colony?

Sterile workers should direct equal effort to raising their fertile brothers and fertile sisters to reproductive maturity. worker efforts should help bro and sis

Termites

Termite colonies can be massive structures dominated by a matedpair called the king and queen. -Unlike the hymenopterans, these latter two groups are both diploid, which present the challenge of understanding the conditions that favor eusociality in these species. -With a few exceptions, these sons and daughters act as workers in the termite society but can become sexually mature if either the king or the queen dies. The king and queen produce sons and daughters by sexualreproduction; both types of offspring serve as workers. Offspring remain sexuallyimmature unless the king orqueen dies. Many species have a cast of termite soldiers, which have verylarge heads and help todefend the nest Plug head in hole to defend attackers (soldier termites do this) -Many species of termites also have a second caste of nonreproductive individuals known as soldiers. As their name implies, soldiers help to defend the nest against intruders such as ants. b) A queen termite (Macrotermes gilvus) living deep inside a colony surrounded by workers. Because her primary role is egg production, the queen's abdomen is much larger than that of workers and soldiers. large termite abdomen

Territories

Territory: any area defended by one OR MORE more individuals against the intrusion of others. Many species of animals have evolved to LIVE NEAR their CONSPECIFICS by establishing a territory. A territory is any area defended by one or more individuals against the intrusion of others. WHY DEFEND TEER? Territories typically are valuable because they contain resources. These resources might be a concentration of food or a type of nest Defending a high-quality territory generally assures greater resources (e.g., food, nest sites). Territories can be transient or relatively permanent. TRANSIENT, PERMANENT, depending on the persistence of the resources in the territory and how long an individual needs those resources. IF RUNNING OUT AND INDIV STILL NEEDS, MIGHT NOT DEFNED MORE Examples: Many migratory bird species will establish summer breeding territories for months.-->geese stay in summer, Canada goose leave when less humans but eat trash and hang out in New York and less predators so have become park pest, STAY IN TERR FOR TRASH IN SUMMER? have winter and summer grounds (When breeding is complete for the season, migratory species move on to their wintering grounds where they establish new territories) Shorebirds that stop along their migration route may defend feeding areas for a few hours or days before continuing on their journey. Many birds in spring coming to stopover areas like JFK, birds stop for hrs to fuels and those coming first do best DEFEND QUAL AREAS W RESOURCES MEANS MORE ATTRACTIVE IF CAN DEFEND RESOURCES This behavior typically improves the attractiveness of a territory holder as a mate, and therefore its fitness. the largest males defend the largest territories and males with the largest territories have access to the greatest number of female LARGE MALE->LARGE TERR->BEST FEM ACCESS log index fem abundance increase w territory size in roe deer -neotropical migratory songbirds typically breed in temperate regions (in summer in their colder range) and then travel long distances to spend the majority of the annual cycle in tropical wintering areas. -hummingbirds and other nectar feeders defend individual flowering bushes and abandon them when those bushes cease producing flowers. benefits of defending the resource outweigh the costs of keeping conspecifics out of the territory,, resource must b defendable too

A breeding pair of birds receives help raising their young from an unrelated male bird. How might providing this assistance improve the fitness of the unrelated male bird? helpers and cooperative fitness

The cooperative relationship helps the unrelated male survive until he can find a mate and produce offspring of his own. Cooperative breeding can increase a helper's fitness if it increases the chances of a helper finding a mate and producing its own offspring later in life. For example, some male pied kingfishers, a species of bird, will assist in rearing the offspring of other pied kingfishers, even if they're unrelated. The cooperative relationship increases the unrelated helper's chances of surviving until he can find a mate of his own and produce his own offspring. Fitness ultimately depends on the number of viable offspring that an individual produces. A helper bird that never produces any offspring, or produces fewer offspring than he would if he did not help, has reduced fitness. Even if the bird has a longer life of his own or raises adopted chicks, his genes will not survive to the next generation.

What is the effect on other alder shrubs of artificially damaging the leaves on one alder?

The damaged shrubs release a chemical that signals all nearby alder shrubs to defend against herbivory. NOT signals only closely related shrubs to defend against herbivory.

Regardless of their complexity, all social behaviors balance costs and benefits to the individual, and the in which these behaviors exist.magnitude of these costs and benefits is often determined by the ecological ?

conditions Like morphology and physiology, behavior is strongly influenced by genetic factors and therefore is subject to evolutionary modification by natural selection The evolution of behavior becomes complicated when individuals interact within a social setting, and the interests of individuals within a population may either coincide or conflict.

In female-only eusociality, females are highly relatedbecause of haplodiploidy, whereas in male-female eusociality, living inside food promotes

Under these conditions, a large r is no longer required to favor eusociality naked mole rats leave the home colony to form new colonies-->dont need super high relatedness, instead if would lose direct ben from leaving colony Eusocial behavior could evolve if the cost of leaving a colony is highdue to a low likelihood of surviving; this reduces the cost of foregoingreproduction. normally higher cost foregoing reproduction

kin recognition in plants

When grown with nonrelatives, however, it allocated more of its energy to growing a greater mass of fine roots. In short, the plant could distinguish between relatives versus nonrelatives and allocated a less competitive strategy against its relatives. Kin recognition in plants. When grown alone or with relatives, the sea rocket plant allocates less energy to growing fine roots. When grown with nonrelatives, the plant allocates more energy to growing fine roots, which makes it more competitive for soil resources.

There are four types of social interactions

When the attacked individual responds—by standing its ground or by fleeing—it becomes the donor of this subsequent behavior Every interaction between two individuals has the potential to affect the fitness of both individuals, in either a positive or negative way

Termites are a diploid eusocial species in which a colony's queen and king produce both sons and daughters through sexual reproduction. What evolutionary reasons may explain why workers forgo reproduction unless the king or queen dies?

Workers increase their indirect fitness by contributing to the survival of their siblings. Workers that leave the home colony are unlikely to establish a new colony. Eusociality has arisen in multiple groups of diploid animals, including the isopterans, or termites, and two mammalian species of mole rats. Current data suggest that eusociality evolves when the suppression of reproduction in worker colony members leads to a higher average inclusive fitness through indirect fitness. In termites, data suggest that inclusive fitness is boosted for two reasons. First, the likelihood that a worker can successfully establish a new colony is low, therefore the average direct fitness of workers is low. Second, the indirect fitness of workers is high. In diploid systems, the average coefficient of relatedness between siblings or between a parent and its offspring is the same at 0.5. If a worker's potential to produce sons and daughters by establishing a new colony is low, then the worker who contributes to the survival of thousands of siblings has a higher indirect fitness than direct fitness. The average inclusive fitness of workers is higher when they remain with their mother colony. In diploid eusocial organisms, the direct fitness of the reproducing pairs is higher than that of workers, and the indirect fitness of workers is higher than that of reproducing pairs. Furthermore, diploid workers are as closely related to their siblings as they would be to their own offspring. It is siblings in haplodiploid systems that are more closely related to their siblings than their offspring.

Hymenoptera, which includes bees, wasps, and ant This method of reproduction is detailed in Figure 9.15. Because one sex is haploid and the other sex is diploid, the ? are said to have a ? sex-determination system. As we will see, this sex-determination system helps to favor the evolution of eusociality. strong ? in coefficients of relatedness. The queen has the same genetic relationship to sons as she has to daughters (r = 0.50), so she can be relatively indifferent to the sex of her reproductive offspring asymmetry between parents and her offspring or siblings

You may recall that this group of insects produces sons by laying unfertilized eggs and produces daughters by laying fertilized eggs hymenopterans is haplodiploid female worker in bees, ants, wasps Daughters are produced when a queen's haploid gamete is fertilized by a drone's haploid gamete and it develops into a diploid daughter. asymmetries with haplodiploidy in genetic relatedness so she can be relatively indifferent to the sex of her reproductive offspring

Which statement does NOT describe a possible behavior of a donor?

a blue jay catching food, which is accidentally discovered by a different blue jay

You are mountain-climbing in the Rockies when you come across a small aggregation of sheep. As you and the small group of ewes watch, you notice that two rams begin fighting every few minutes. One by one, the fights end in one ram winning and one ram losing and limping away. After many such matches, a single ram that has not lost any fight trots up to the ewes and mates with them. No other rams mate with any ewes. What type of social interaction did you observe on this mountaintop?

a dominance hierarchy those winning fights get more mates after a series of fighting foes up to ewes and mates

Using these coefficients of relatedness, we can calculate the indirect fitness as the fitness benefit gained a recipient relative (B) multiplied by the coefficient of relatedness between the donor and the recipient relative (r):

r Amt of genes shared: since there is relatedness, ndividual has a higher probability of leaving more copies of its genes in the next generation by promoting the fitness of its closest relatives hence why part of indir fitness, and thus some fitness benefit B to RECIPIENT also donor cost (c) must b outweighed

so extremely social that we call them eusocial. Eusocial (i.e., "truly" social) species are distinguished by their display of all four of the following characteristics: Several adults ? together in a group Overlapping ? of parents and offspring living together in the same group Cooperation in ? and ? care ?? by one or a few individuals, and the presence of ? individuals Among the insects, eusocial species are limited to the order ?, order ?, which includes? Other than insects, the only animals known to be eusocial are two species of mammals that live in underground tunnels in Africa: the ?(Heterocephalus glaber)?(Fukomys damarensis). Eusocial species are fascinating to ecologists because most individuals in a eusocial group don't ? sexually or reproduce. Instead, they specialize at tasks that include ? for the group or taking care of the subsequent offspring of their parent nonreproductive individuals are specialized for these tasks, they are known as sterile ?. A caste consists of individuals within a social group that share a specialized form of ?

adults living in groups overlapping generations nest building and brood care Reproductive dominance, sterile Isoptera (termites) Hymenoptera, bees, wasps, and ants naked mole rat , and the Damaraland mole rat ecosystem processes. Eusocial insects pollinate plants, consume plant and animal material on a large scale, and recycle wood and organic detritus., Their dominance in the world is due in large part to the immense success of eusociality Pictured here is a queen and her young daughters that are tending a fungus garden deep inside their underground nest. dont mature sexually, defending and foraging (tasks helping group) nonreproductive individuals are specialized for these tasks, they are known as sterile CASTES. A caste consists of individuals within a social group that share a specialized form of BEHAVIOR worker honeybees AND LEAF-CUTTING ANTS are a caste that works for the hive but typically do not reproduce lack any reproductive output and therefore lack any direct fitness

This figure shows the results of an experiment on American Sea Rockets. Which of these statements CANNOT be inferred from this graph? American Sea Rockets _____.

allocate less energy to a competitive strategy when grown with relatives than with nonrelatives are thus able to distinguish between relatives and nonrelatives both these inferred grow more fine roots when grown together than they do when grown alone

Male turkeys display at leks by puffing up their feathers and strutting back and forth to attract females. Males may either display ? or with other males (Figure 9.12). When a group of males displays together, only the ? male copulates with the females that they attract. why subordinate help when not mating themselves cost to subordinate by not breed as solo mate

alone or others (coalition displays), display site=lek dominant copulate Males in a coalition were more closely related than males drawn at random from the population. Indeed, the average coefficient of relatedness between groups of displaying males was 0.42, which suggests that grouped males represent a mixture of full brothers (r = 0.5) and half-brothers (r= 0.25) all related to come degreee in coalition Dominant males in a coalition sired an average of 6.1 offspring, subordinate males in a coalition sired 0 offspring; and males that displayed alone sired an average of 0.9 offspring By being a part of the coalition, the subordinate male forgoes the ability to breed as a solo male, which would have allowed him to sire 0.9 offspring., Therefore, his cost of being altruistic is 0.9 offspring. By helping his brother or half-brother become highly successful at attracting females, he allows his brother to sire 6.1 offspring. As we have learned, the subordinate male's average coefficient of relatedness to his brother is 0.42. so 6.1 * .42 = 2.6 much greater than .9 cost, indirect benefit (explains inclusive fitness), obtains greater inclusive fitness by helping his brother than by going out on his own to attract females. B * r > C-->The evolution of altruistic behavior becomes clear when we examine the costs and benefits in an equation indirect benefit = B * r rearrange this equation, we can show that for altruism to evolve, the cost-benefit ratio must be less than the coefficient of relatedness between donor and recipient: This means that a subordinate male obtains greater inclusive fitness by helping his brother than by going out on his own to attract females.

A dominance hierarchy is most likely to form when _____.

an individual is surrounded by so many members of its species that it is impractical to defend a territory against them all there is a steady and ample supply of resources supporting members of a species for a long time in a given area-->supports territory

When animals cooperate, both the animals giving help and those receiving help gain a direct fitness benefit. A wolf may cooperate with other wolves to hunt large prey that no wolf could take down on its own. A meerkat may take a turn guarding the colony and, in return, be able to rest or eat while another meerkat takes its rotation. These animals cooperate because each animal benefits directly by participating. lion killing , meerkat guard=cooperaiton Altruism only provides direct fitness benefits to the animal receiving help. The animal providing help does not benefit directly. Scientists suspect that altruism evolves in situations where an individual cannot pass on its genes to its own offspring. A non-breeding animal can still get copies of some of its genes into the next generation if it helps a relative raise its young. Altruism provides indirect fitness benefits for the helper. Altruism confers higher indirect fitness on close relatives than on more distant relatives. For example, sterile worker honeybees share most of their genes with their fertile sisters. Helping their fertile sisters grow and reproduce improves the chances that some of the sterile worker's genes will pass to the next generation. Lack of breeding territories drives altruism in scrub jays. If a young adult scrub jay cannot find its own territory, it may help its parents raise a new clutch of offspring. The helper jay shares half its genes with these siblings. By helping, the young jay can at least pass some of its genes into the next generation.

both gain from cooperation altruism-The animal providing help does not benefit directly., higher indirect fitness on close relatives than on more distant relatives Cooperation Unrelated wolves that form a pack are more likely to catch enough prey than they would be if they each hunted alone. Meerkats have more time to find food and tend to offspring if all the meerkats take turns guarding the colony of several families.-->they get benefit in group guarding Altruism The fertile sisters of sterile honeybee workers need feeding and tending if they are to grow and reproduce. A young adult scrub jay cannot find a breeding territory of its own so it remains with its parents and helps raise their next brood of chicks. ask if they get some benefit?

Why does altruism exist? RELATEDNESS TREE

coefficient of relatedness: the numerical probability of an individualand its relatives carrying copies of the same genes from a recentcommon ancestor cannot be individual selection-selection is based on inclusive fitness in altruism including direct and indirect effects associated with behavior, must help related over unrelated Share half genes w parents, will save parents due to relatedness Kin selec favors indirect fitness, altrusim selfish acts that cannot evolve by individual selection otherwise would move on, works Humans may not be related to somebody, altruism could help fitness of leaving behind genetic material not need be related If we next consider the focal individual and its siblings, we see that these two individuals have a 0.5 probability of receiving copies of the same gene from a parent . In the case of two cousins, the probability drops to 0.125 (one in eight) of inheriting copies of the same gene from one of their grandparents, which are their closest shared ancestors

Animals are most likely to defend territories when _____.

there is a steady and ample supply of resources to support members of a species for a long time in a given area In this scenario, territories would be less likely because all individuals would be able to obtain the resources they need. the benefits of defending a territory override the costs of defending resources on the territory not resources are only available for short periods of time, may during this but not for sure just simple ben over cost

. There are 213 bird species that exhibit ? breeding, which is approximately 9 percent of all bird species in the world. Of these 213 cooperative-breeding species, 55 percent have helpers at the nest that are close relatives, 30 percent have helpers that represent a mix of relatives and nonrelatives, and 15 percent have helpers that are entirely nonrelatives.

cooperative breeding to help territories The alternative strategy of a single mated pair of trumpeters trying to hold a territory is not feasible; it takes more than two birds to defend a territory. As a result, more fitness can be obtained by helping a nonrelative and someday have an opportunity to breed compared to going it alone with a male, not being able to hold a territory and not breeding not regular coalitions where all birds related, In some cases, such as white-winged trumpeters (Psophia leucoptera) in South America, unrelated females join a cooperative breeding group to help raise the offspring (Figure 9.13). Should the breeding female of the group die, one of the younger females gets to take her place and begins breeding Cooper groups, fem raise unrelated offspring -As a result, more fitness can be obtained by helping a nonrelative and someday have an opportunity to breed, may breed if group's main breeding female dies nonrelatives that help raise unrelated offspring can also gain substantial fitness later in life by learning how to be better parents. will have actual territory could not defend alone, and parenting skills later -The concept of kin selection has given ecologists a better understanding of the evolutionary reasons underlying a wide variety of altruistic and selfish behaviors in animals. C/B<r

Another survival mechanism available to social groups is a phenomenon known as the ? effect

dilution effect reduced, or diluted, probability of predation to a single animal when it is in a group. In an aggregation of prey, the predator has many prey choices, an individual living in such a group has a lower probability of being caught. benefit of large groups

When the benefits of living in a group are greater than the benefits of defending resources in a particular area, animals are likely to maintain _____.

dom hierarchy

when the benefits of living in a group override the benefits of defending a territory, individuals of many species form ?

dominance hierarchies. Once individuals order themselves into a dominance hierarchy, subsequent contests among them are resolved quickly by and in favor of higher-ranking individuals. In a linear dominance hierarch RESOLVED BASED ON HIERARCHY ROLES AFTER ESTABLISHING THEM When resources are available for only short periods of time or when the benefits of living in a group override the benefits of defending a territory-->RATHER THAN TERRITORY HIERARCHY

Eusocial insect societies BAW honeybees: Whether an individual becomes a sterile worker female or a fertile female is determined by the length of time the larva is fed?

dominated by one or a few egg-laying females, referred to as queens The queens in colonies of ants, bees, and wasps mate only once during their lives and store enough sperm to produce all their offspring The queens in colonies of ants, bees, and wasps mate only once during their lives and store enough sperm to produce all their offspring The nonreproductive progeny of a queen gather food and care for developing brothers and sisters, some of which become sexually mature and leave the colony to mate and to establish new colonies. all ants, bees, wasps honeybee societies have a simple organization. The offspring of a queen are divided among a sterile worker caste that is female and a reproductive caste that consists of drones and future queens fed royal jelly. the worker caste represents an arrested stage in the development of reproductive females royal jelly=reach sex maturity

More why altruism exists

e:Male turkeys display to females alone or in a coalition. Male turkeys display at leks by puffing up their feathers and strutting back and forth to attract females. Males may either display alone or with other males (Figure 9.12). When a group of males displays together, only the dominant male copulates This raises the question of why the subordinate males in a pair spend time and energy displaying when they will not be given a chance to produce any offspring with the female -SUBORD THAT FOREGO STILL HELP DISPLAY -Researchers obtained their first clue by using genetic data. Males in a coalition were more closely related than males drawn at random from the population. When a coalition displays together, onlythe dominant male gets to breed. THE TURKEY Coalitions are mixtures of full (r = 0.5)and half brothers (r = 0.25); average r is0.42. average coefficient of relatedness between groups of displaying males was 0.42 subordinate males in a coalition sired 0 offspring; and males that displayed alone sired an average of 0.9 offspring Males that displayed alone (i.e., not in a coalition) sired an average of 0.9 offspring. By being a part of the coalition, the subordinate male forgoes the ability to breed as a solo male, Therefore, his cost of being altruistic is 0.9 offspring. This means that a subordinate male obtains greater inclusive fitness by helping his brother than by going out on his own to attract females. Although kin selection helps us understand how cooperative breeding can be favored by natural selection, Dominant males in a coalition sired an average of 6.1 offspring.Indirect fitness benefit of subordinate male in a coalition better to help as wingman for dominant male to pass on your genes 6.1*.42>0.9=2.562 indirect benefit 2.6 greater than 0.9-go and get wingman lucky , dont go out on own adn mate Benefit is 6.1 and average coefficient of relatedness Greater than offspring sired by displaying alone males, so selection favoring altruism and coalition breeding so wingman can help altruism and cooperative ebreeding favored in many situations

Origins of eusociality

eusociality3Eusociality has independently evolved many times. Being haplodiploid favors the evolution of eusociality; it is not required for its evolution. (Mole rats, also termites) . It is tempting to conclude that eusociality is caused by a haplodiploid sex-determination system, but many haplodiploid species are not eusocial, and some eusocial species—such as termites and naked mole rats—are not haplodiploid -while being haplodiploid appears to favor the evolution of eusocial behavior by providing large indirect fitness effects when workers do not breed and instead help their sisters Eusocial behavior could evolve if the cost of leaving a colony is high due (net negative) to a low likelihood of surviving; this reduces the cost of foregoing reproduction .Example:Some naked mole rats leave the home colony to form new colonies.Most of these colonies do not persist for more than a year, leading to a reduc, large r not required to favor eusociality more behavioral -As a result, the cost of forgoing reproduction by not leaving the home colony—in terms of lost direct fitness—is small. When this cost(of forgoing reproduction) is small, a large coefficient of relatedness is no longer required to favor eusocial behavior. -OFFSPRING DO OFTEN FAIL TRYING TO MAKE NEW -. However, this equation could also be satisfied if the cost of forgoing personal reproduction (i.e., the loss of direct fitness) is very low. -, we have focused on the importance of the coefficient of relatedness with the idea that the coefficient needs to be relatively high to favor eusociality. -If individuals that choose to leave a colony have a very low likelihood of surviving and setting up a new colony, then their direct fitness is very low. low direct benefit of fitness from leaving, will just help others w related genes -favored by the inclusive fitness of the altruistic sterile offspring -Others have argued that it has evolved to enhance the direct fitness of parents that force the offspring to forgo reproduction -Regardless of their complexity, all social behaviors balance costs and benefits to the individual, and the magnitude of these costs and benefits is often determined by the ecological conditions in which these behaviors exist. -Like morphology and physiology, behavior is strongly influenced by genetic factors and therefore is subject to evolutionary modification by natural selection bpm all modifications w nat selection

SOCIAL RESPONSES TO HERBIVORY

experiment on a shrub in Germany known as alder (Alnus glutinosa) in which they manually REMOVED LEAVES OF SHRUB, MIMIC HERBIVORY leaves of one shrub and then examined the herbivory of other alders at different distances away. They then repeated the experiment in 10 forests. Seven days later, they examined how much NATURAL HERB OTHER PLANTS herbivory the other alders received by an herbivore known as the alder leaf beetle As the researchers examined the percent leaf damage from 11 to 1 m away from the manually defoliated alder, they found that as they got closer to the defoliated alder, leaf damage declined from more than 10 percent to less than 3 percent CLOSER TO HUMAN DEFOLED=LESS HERBIV less leaf damaged closer to one mimicking having been eaten In most cases, the underlying mechanism is that attacked plants release chemicals when they are attacked; nearby plants can detect these chemicals and respond by increasing their own defenses some plants can even respond to other species of plants that are attacked by herbivores. In most cases, surrounding alders could detect and respond to the CHEMS RELEASED BY defoliated individual, they found that alders near the defoliated individual experienced less herbivory by the alder leaf beetle-->increased defenses thinking predator nearby responding to attacked conspecifics initially appears to be a social behavior, a key question is why the attacked plant is emitting a chemical signa the chemicals may function to fight microbial infections after the herbivore attack. IMMUNE CHEMCS Alternatively, the plant may be emitting chemicals from attacked leaves to stimulate defenses in leaves on other parts of itself CHEMS FOR DEFENSE STIMULAITON IN SAME PLANT, NOT ACTUALLY COMMUN W OTHERS BUT THEY PICK UP, Despite this lack of intent to communicate to conspecifics (or heterospecifics), the neighboring plants are always free to "eavesdrop" on this chemical signal and respond in a manner that improves their fitness. If plant signaling of herbivory to conspecifics represents altruism, we should see it more often in plant species that live with closely related kin nearby, since the emitted chemicals are only effective at inducing defenses over fairly short distances (i.e., less than 10 m). 10 m limit to chem defense the emitted signals may simply be emitted with no intention of signaling a conspecific indirect fitness benefit from warning nearby close relative, If plant signaling of herbivory to conspecifics represents altruism, we should see it more often in plant species that live with closely related kin nearby, In the limited number of plant species that have been investigated, researchers have observed signaling in plant species that STILL DO NOT have close relatives nearby. Thus, much more research needs to be done to determine whether actions of plants that are signaling herbivore attacks can be considered a social behavior, such as cooperation or altruism. possibly recognize kin and emit chem signals for cases of herbivory In contrast to responses to herbivory, there is growing evidence that plants can distinguish between relatives and nonrelatives when faced with competition. experience shade from another plant, they respond by trying to grow taller to outcompete the neighboring plants for sunlight. If that neighbor is a nonrelative, growing taller is an adaptive strategy that provides an increase in direct fitness. cost of reduced indirect fitness from shading a relative Such altruistic behavior would be more favored if an individual plant could distinguish relatives from nonrelatives. However, kin recognition may not be required if being surrounded by relatives is a common occurrence in a given species, such as plants that reproduce clonally or through self-fertilization with offspring that do not move far away from the parent plant. plants can distinguish between relatives and nonrelatives when faced with competition. If that neighbor is a close relative, growing taller may provide direct fitness benefits, but at the cost of reduced indirect fitness from shading a relative Such altruistic behavior would be more favored if an individual plant could distinguish relatives from nonrelatives. However, kin recognition may not be required if being surrounded by relatives is a common occurrence in a given species, CLONAL, SELF FERT PLANTS SURROUNDING BY RELATIVES LIKELY When the sea rocket grew alone or with relatives, it produced a relatively low mass of fine roots. When grown with nonrelatives, however, it allocated more of its energy to growing a greater mass of fine roots. grew less didn't try outcompeting for resources like light w relatives In a greenhouse experiment, researchers grew the plant in pots either as solitary individuals, as an individual surrounded by three relatives, or as an individual surrounded by three nonrelatives. You can see the results in Figure 9.19. When the sea rocket grew alone or with relatives, it produced a relatively low mass of fine roots. When grown with nonrelatives, however, it allocated more of its energy to growing a greater mass of fine roots When grown with nonrelatives, however, it allocated more of its energy to growing a greater mass of fine roots. In short, the plant could distinguish between relatives versus nonrelatives and allocated a LESS COMPET competitive strategy against its RLEATIVES.

Which of these statements about group size in yellow baboons can be inferred from these graphs of group size versus distances traveled in search of food and of stress hormones?

group optimal size, measure hormone and traveling for food dist In large groups the costs associated with stress are more important than the cost of travel distance. The relative importance is difficult to calculate without knowing the exact fitness consequences. cannot just use magnitude of graph quantities The largest and smallest groups would be better off living alone. If this were true, there would be no very small or very large groups The cost-benefit ratio in yellow baboons changes in different group sizes.

In naked mole rats, the dominant females force subordinate individuals to forgo reproduction to help raise their siblings by _____.

harassing them and causing elevated stress levels

A female wasp would receive the greatest inclusive fitness by _____.

helping raise 200 sisters

Altruism should be favored by natural selection when the _____.

inclusive fitness from altruistic behaviors exceeds the inclusive fitness from selfish behaviors

Why does altruism exist?

indirect fitness benefit = B x r Using these coefficients of relatedness, FOR FITN BENEFIT B= benefit given to a recipient relative R = coefficient of relatedness between donor and recipient identical twin r = 1 individual has a higher probability of leaving more copies of its genes in the next generation by promoting the fitness of its closest relatives and gains nothing by promoting the fitness of nonrelatives. Altruism will be favored when B times the recipient's r is greater than the directfitness cost to the donor (C):B x r > C Or rearranged...C/B < r RELATEDNESS TO DONOR AND BENEFIT FOR RECIPIENT OF ALTRUISM may not be related but altruism favored still if not related, effect is being able to pass on genes-hallmark movie For altruism to evolve, the cost-benefitratio must be < than r (red area in graph) Die to save twin may be half cousins or something in whire Understanding the role of kin selection and coefficients of relatedness helps resolve the puzzle of how altruistic social interactions can evolv Whereas selfish interactions provide direct fitness benefits to the donor, altruistic interactions provide indirect fitness benefits to the donor, weighted by the coefficient of relatedness between the donor and the recipient. If the inclusive fitness of altruistic behaviors exceeds the inclusive fitness of selfish behaviors, then altruism will be favored by natural selection. -As we have noted, indirect or kin selection occurs because an individual and its relatives carry copies of some of the same genes inherited from a recent common ancestor.

An individual would gain higher inclusive fitness by helping his brother mate than by himself mating if his _____.

indirect fitness benefit is more than two times his direct fitness cost

Social behaviors:

interactions with members of one's own species,including mates, offspring, other relatives, and unrelatedindividuals -animals doing stuff for selves Social behaviors have a GENETIC basis and are subject to natural selection Selection has favored cohesive groups and CONSTRAINED antagonism. more ******** than ever before Many organisms other than animals exhibit social behaviors. Examples: Bacteria and protists can secrete chemicals to sense each other, and react in"friendly" or "aggressive" ways. Damaged plants emit volatile chemicals that warn other plants In other cases, individuals are attracted to each other for BREEDING FOR GROUP SOCIAL LIVING. Individuals can also aggregate because they are independently attracted to the SAME HABITAT or RESOURCE. Animals generally form groups to increase their SURVIVAL(VS PEDATORS), rate of FEEDING, or success in finding MATES. -3 GROUP REASON SFM

THE ORIGINS OF EUSOCIALITY

it is clear that eusociality has evolved independently many times. but many haplodiploid species are not eusocial, and some eusocial species—such as termites and naked mole rats—are not haplodiploid. haplodiploid appears to favor the evolution of eusocial behavior by providing large indirect fitness effects when workers do not breed and instead help their sisters, coefficient of relatedness with the idea that the coefficient needs to be relatively high to favor eusociality. However, this equation could also be satisfied if the cost of forgoing personal reproduction (i.e., the loss of direct fitness) is very low if basically no cost not repro (the turkeys? had fairly low 0.9 cost by helping others in leks/coalitions, if they have low direct fitness e.g. low survival chance If individuals that choose to leave a colony have a very low likelihood of surviving and setting up a new colony, then their direct fitness is very low. In naked mole rats, for example, some individuals leave the home colony to form new colonies, but most of these small new colonies do not persist beyond 1 year cost of forgoing reproduction by not leaving the home colony—in terms of lost DIRECT fitness Many researchers have argued that it has been favored by the inclusive fitness of the altruistic sterile offspring. Others have argued that it has evolved to enhance the direct fitness of parents that force the offspring to forgo reproduction.

indoor fitness calc

kingfisher-adult male first yr help raise offspring->primary helper feed and protect chicks, not always related could have stepparents secondary helpers-unrelated helping feed and protect chicksDelayers are unrelated and do not help and wait until the second year to reproduce. After two years, delayers have reduced inclusive fitness relative to secondary helpers.

The dilution effect is an important benefit of _____ groups.

large

A _____ is a location where large groups aggregate only to attract mates.

lek

we can see that altruism is favored whenever the cost to the donor is ?, the benefit to the relative is ?, and the donor and its relative are closely related., high ? Whereas selfish interactions provide direct fitness ? to the donor, altruistic interactions provide ? fitness benefits to the donor, If the inclusive fitness of ? behaviors exceeds the ? fitness of selfish behaviors, then altruism will be favored by natural selection.

low C, high B, high r -->equation for why altruism evolves Understanding the role of kin selection and coefficients of relatedness helps resolve the puzzle of how altruistic social interactions can evolve. direct benefit to donor , altruism indirect donor benefit , calc inclusive fitness for each altruistic exceeds selfish inclus fitness

You are hiking in South America and you come across a group of small primates living in a small stand of fruit trees that seem to bear fruit that no other trees in the forest produce. After watching the primates for a while, you observe that they consume only this fruit and nothing else. Further, you observe that the males of this group are fairly evenly spaced and stay in the same place. However, the females move about freely. Males that defend a fruited area let the females consume the fruit but often try to mate with the females after they do so. What type of social grouping system do you conclude you have stumbled upon in this forest?

males defending territories

You are studying the mating habits of a hummingbird species in Puerto Rico in which males congregate in leks to attract females. You observe that as the number of males in a lek increases, the number of females who arrive to observe the male courtship displays increases. However, as more males aggregate in a site, the probability of each male successfully mating with a female goes down. You observe leks of different sizes and record the number of females who watch the lek and the probability of each male successfully mating with a female in the following table:

prob each mating w lek down w more males num fem watchers go up, but Per-male probability of mating with a female go down quick bruv If the likelihood that a male will mate with a female is determined by the number of females watching a lek times the probability that a given male will mate with a female, what is the optimal lek size for a male to join to mate with a female? Per-male probability of mating with a female down as Number of female watchers goes up 2 watcher = .86 Likelihood of mating 4 = 1.48 5 watcher=1.6-->-->8 individuals optimal lek size greatest likelihood based on watchers and indiv prob of mating 1.56 for 6 Likelihood of mating = (number of female watchers) x (per-male probability of mating with female

A territory is any area defended by one or more individuals against the intrusion of others. Territories typically are valuable because they contain ?. These resources might be a concentration of food or a type of ? that is in limited supply, such as a hole in a dead tree that a bird can use for a nest. Territories can be either ? or relatively ?

resources, nest, transient OR permanent, depending on the persistence of the resources in the territory and how long an individual needs those resources Defending a high-quality territory generally ensures greater resources, such as abundant food or nest sites. This behavior typically improves the attractiveness of a territory holder as a mate, BC OF RESOURCE THEY HAVE In roe deer (Capreolus capreolus), the largest males defend the largest territories and males with the largest territories have access to the greatest number of females As long as a resource can be defended and the benefits of defending the resource outweigh the costs of keeping conspecifics out of the territory, animals are likely to maintain territories. Hummingbirds and other nectar feeders defend individual flowering bushes and abandon them when those bushes cease producing flowers. For example, shorebirds that stop at several points along the way of their long migration defend feeding areas for a few hours or days and then continue their migratory trip

An ant colony normally has a ? queen that can live for 1?. Early in her life, the queen participates in a mating flight with males.

single queen, 10 to 20 years The sperm she receives are then held inside her body and remain viable for the rest of her life. She uses them sparingly when fertilizing eggs to make daughters; seperm stored in body from mating w many male, viable for life and use selectively to fertilizing eggs in some species, the queen releases only one or two sperm per egg. Occasionally, she lays unfertilized eggs to make sons whose only function is to mate with other queens unfertilized SONS for future queen mating The millions of individuals in the nest are daughters of the same queen and sisters to each other. They all forgo reproduction.

The differences in subcastes are thought to be a ? ? to different diets the ants receive as larvae.

subcaste difs = phenotypically plastic response to larvae diets For example, when workers are young, they spend most of their time inside the nest, cooling the nest, building new tunnels, and raising the larvae. When large leaf pieces arrive at the nest, another group of workers cuts the leaves into smaller pieces and a third group of workers mashes the leaf pieces into tiny bits. -tunel building in nest=youngest, then cutting, then mashing he smallest workers bring fungus to tend to the leaves, fungus brought to final mashed leaves the workers even adjust the nutrient mixture given to the fungus. Since the ants prefer to eat the fungal threads and not the reproductive mushrooms that the fungus produces, the workers adjust the amount of carbohydrates and proteins that they give to the fungus to prevent the fungus from making mushrooms. The oldest and largest ants act as soldiers and go out of the nest to collect leaves. Some ants climb into trees and cut large pieces of leaves that drop to the ground, while others relay the cut leaf pieces back to the nest. climbers, large piece cutters, others relay piece to nest Researchers have recently discovered that these mandibles become dull over time, causing older workers to take twice as long to cut a leaf. carrying if dull mandible This change in job allows older individuals to continue contributing to the ant society. a species of parasitoid fly that is specialized to hunt large leaf-cutter ants lays its eggs inside the necks of foraging ant Smaller individuals, which are less attractive to the fly, forage during the day. At night, when the parasitoid flies do not hunt, the larger, more effective forager ants go out to collect leaves Small workers also guard larger ants by riding on leaves that the larger ants carry.

a few other species are also eusocial, including termites and a group of mammals known as naked mole rats. Unlike the hymenopterans, these latter two groups are both diploid, which present the challenge of understanding the conditions that favor eusociality in these species. Termite colonies can be massive structures that are dominated by a mated ? called the king and queen (Figure 9.16a). Because the queen's role is almost entirely limited to egg production, her abdomen is grossly distended to allow her to produce thousands of eggs ( Rather surprisingly, there is only one group of animals in the ocean that is eusocial. The ? shrimps

termite king-queen pair mole queen and mult kings The king and queen produce sons and daughters by sexual reproduction With a few exceptions, these sons and daughters act as workers in the termite society but can become sexually mature if either the king or the queen dies maturity of offspring with parent death Many species of termites also have a second caste of nonreproductive individuals known as soldiers. defend the nest against intruders such as ants. Soldiers typically have a very large head that can be used to block the openings of a termite nest the naked mole rat and the Damaraland mole rat. These rodents live in underground tunnels in African grasslands in colonies of up to 200 individuals. In naked mole rats, a single queen and several kings are responsible for all the reproduction in the colony, and all individuals are diploid Although the workers in the group are capable of reproducing, they care for their younger siblings and the colony rather than reproduce. (forego repro but mature), termites not mature? subordinate males and females do not forgo reproduction willingly. Instead, the dominant female harasses them, which causes them to become stressed. Stress reduces the levels of sex hormones snapping shrimps These cooperative breeding societies include either a single queen or multiple queens, depending on the species, and many nonbreeding helpers. On the reefs, food is relatively scarce and the defense of the scarce food requires a large number of shrimp to defend it, In some species, the queen has an especially large claw that it uses to fight any subordinate females in the group that try to breed. In other species, the subordinates do not breed as long as the queen is present, even if they do not come into contact with the queen. In this latter case, the queen may be emitting a chemical that causes the subordinates to not attempt breeding.

When the benefits of defending particular resources are greater than the costs of keeping out conspecifics, animals are likely to maintain _____.

territories

Under what conditions does natural selection favor individuals that live in groups, such as herds or flocks?

when the risk of predation is reduced for individuals in a group when working as a group makes it easier for individuals to obtain enough food when the chance of finding a high‑quality mate increases in a group predation, food, mate obvi Many types of animals live in groups for at least part of their lives. Birds form flocks to migrate or find scarce food. Lions form prides to hunt more efficiently. Fish swim in schools as protection against predators. N Natural selection favors group living when the benefits of being in the group outweigh the individual's costs. Perhaps the most common factor favoring group living is that individuals in a group are less likely to be targeted by predators than when they are alone. Predators might choose to attack other individuals in the group. Also, as the group scatters during an attack, predators have difficulty remaining focused on a single individual. Several individuals searching together have a better chance of finding patchy food resources than an individual does searching alone. When one group member finds a patch of food, it alerts the rest of the group so all can come and feed. The amount of food available in an average patch of food often determines the size of the group. A group with too many members will often go hungry and the group will break into smaller groups. Some animals gather in groups(leks) so females can assess the quality of potential mates. In lekking species, such as sage grouse, the males gather together and demonstrate their fitness through competitive displays. Often, most of the females choose to mate with only those few males that the females deemed to have won the competition. A female increases the chances of her offspring surviving to reproduce when she chooses a high‑quality mate. Time spent watching for predators does not increase for an individual living in a group. In fact, individuals in a group generally spend less time watching for predators. When group members share the work of being vigilant, each individual has more time to eat, rest, or tend to young. Having more time for these activities improves an individual's ability to get its genes into the next generation.

Many species make alarm calls when they spot a predator. Which of these potential reasons for making alarm calls is the most likely to be FALSE?

will make Calls that are specific to a certain type of predator can help others to take appropriate actions. -They warn an individual's offspring about potential threats. not that They enhance the dilution effect.

What is the indirect fitness benefit of a worker bee in a eusocial colony who helps the queen, her mother, produce and raise 300 drones, 500 workers, and 250 queens?

worker queen=0.5*(250)=125 worker-worker=0.75(500)=375 worker-drone=0.25*(300)=75 575 637.5 somehow helping the queen so r = 0.5, direct benefit to queen is 750 and for workers and queens 50% related to mother, but drones direct benefit from mother is 1 so 300*1 so 300+750×0.5=675 direct benefit, what is cost ? As you can see in , the mother's relationship to her daughter, and the daughter's relationship to her mother, are still r=.5. A mother's relationship to her son is r=.5 because he received half of her genes, however the son's relationship to the mother is 1 because all of his genes are from his mother. A daughter's relationship to her father is r=.5 because half of her genes are from her father, but a father's relationship to his daughter is r=1 because she has all his genes since he only has one copy. There is no father/son relationship because males result from unfertilized eggs A worker shares 25 percent of her mother's genes with all her siblings and an additional 50 percent of her father's genes with her sisters worker helping queen or drone