Midterm Study Questions
Which of the following two statements are clearly Darwinian puzzles? Salmon can smell a few molecules of chemicals in the stream in which they were born. Adult birds scream when caught by a predator because of the pain. If you add two or three eggs to the nests of some birds, the adult birds rear them successfully along with the young from eggs they laid. Bats can catch moths in complete darkness. Female lions often nurse offspring that are not their own.
A Darwinian puzzle is a trait that appears to reduce the fitness of those that possess it. I, II, and IV are all adaptations that clearly help the individual survive and reproduce. In the case of the salmon, they return to their native mating grounds to spawn and provide a safe habitat for juveniles to hatch. Adult birds might scream to shock the predator into releasing them. Bats have developed echolocation to capture their prey at night. On the other hand, it appears maladaptive to rear chicks that do not have any genetic relatedness to you and or nurse offspring that are not your own. This takes away energy and resources that you could be putting into rearing your own offspring. The correct answer is: III, V
Which of the following is an indication of Darwinian fitness? Select one: A. Cheetahs run faster than the gazelles they prey upon. B. Some species of birds sing louder than other species. C. Stronger baboons can supplant weaker baboons from a group of females. D. Insects are ubiquitous because of their ability to fly.
A and possibly C if by this you think that selection acts on males to be strong. The correct answer is: Cheetahs run faster than the gazelles they prey upon.
If female cockatiel birds with orange cheeks produce more eggs than females with yellow checks then orange cheeks is an evolved adaptation. This statement is: Select one: A. False, because females with yellow cheeks could still have more offspring that live to reproduce than females with orange cheeks. B. False, because there is no guarantee that females with orange cheeks are the best for the long-term preservation of this species. C. True, because there is variation in this species, which is a critical requirement for the evolution of adaptations by natural selection. D. We cannot conclude one way or the other because we are not told whether orange cheeked females outnumber yellow cheeked females.
A is true because fitness is determined by the number of offspring that survive to reproduce. It is possible that yellow cheeked females are producing less eggs but more of those eggs are surviving and having chicks of their own. For B, natural selection acts on the individual rather than the species. For C, true but this does not answer the question of whether orange cheeks are an adaptation. For D, this is irrelevant because selection natural selection is acting on the individual, not the population. The correct answer is: False, because females with yellow cheeks could still have more offspring that live to reproduce than females with orange cheeks.
The moth's genes influence the way the adult animal's nervous system forms connections between its muscles and its wings. Select one: A. genetic-developmental B. sensory motor C. evolutionary history D. adaptive value
A or B, proximate. The correct answers are: genetic-developmental, sensory motor, evolutionary history, adaptive value
The behavior is instinctive. Select one: A. genetic-developmental B. sensory motor C. evolutionary history D. adaptive value
A or B, this is proximate and can either be described as genetic-developmental or physiological-psychological. The correct answers are: genetic-developmental, sensory motor
Unlike domesticated European bees, African bees are prone to attacking large animals that approach their hives. Even experienced beekeepers have trouble working with African bees safely. African bees were introduced to South America and are rapidly spreading northward and hybridizing with domesticated European bees along the way. The "Africanized" hybrids are almost as aggressive as the fully wild African bees. What is a proximate explanation for the difference in behavior between European and African bees?
A proximate explanation is that African and European bees have different levels of an aggression-inducing hormone.
Cover influences the ability of a kangaroo rat to detect the sounds of predators. Select one: A. Proximate B. Ultimate
A, Proximate. This is a sensory-motor mechanism. The correct answer is: Proximate
Males in different populations have different forms of certain genes that influence the development of the song system. Select one: A. genetic-developmental explanation B. sensory motor explanation C. adaptive value explanation D. relating to evolutionary history
A, behavioral genetics. The correct answer is: genetic-developmental explanation
The differences among dialects are environmentally determined, not genetically controlled. Select one: A. genetic-developmental explanation B. sensory motor explanation C. adaptive value explanation D. relating to evolutionary history
A, genetic-developmental mechanism. Although the trait is not genetic, this still explains how the trait arose (environmental factors). The correct answer is: genetic-developmental explanation
Males in different populations are exposed to different songs, an experience that influences the kind of song that the birds learn. Select one: A. genetic-developmental explanation B. sensory motor explanation C. adaptive value explanation D. relating to evolutionary history
A, genetic-developmental mechanism. Explains how the trait arose. The correct answer is: genetic-developmental explanation
Male parental care is common in fish species, but rare in mammal species. Select one: A. Phylogenetic or historical B. Functional advantage or benefit C. Ontogenetic or developmental D. Expression triggering
A, male parental care is a trait shared by many fish relatives but not by many mammalian relatives. The correct answer is: Phylogenetic or historical
When a Wildebeest starts walking in the wrong direction it will bump into other wildebeest in the herd and learn which direction it needs to walk. Select one: A. Proximate B. Ultimate
A, proximate. Learning within the animals lifetime/ developmental The correct answer is: Proximate
Wildebeest orient to the sun to determine their migration pattern. Select one: A. Proximate B. Ultimate
A, proximate. The sun is the mechanism that triggers/determines their choice. Or they are navigating to the sun. The correct answer is: Proximate
The behavior is learned. Select one: A. genetic-developmental B. sensory motor C. evolutionary history D. adaptive value
A, this answers HOW the behavior was performed, the behavioral development/ontogeny. The correct answer is: genetic-developmental
All primates appear to fear snakes or snake-like objects before ever encountering a real snake. Select one: A. Phylogenetic or historical B. Functional advantage or benefit C. Ontogenetic or developmental D. Expression triggering
A, this is sensory bias that originates from shared primate ancestry. The correct answer is: Phylogenetic or historical
Which level of analysis best explains why juvenile male Belding's ground squirrels disperse? Select one: A. Physiological mechanisms B. Ontogenetic processes C. Adaptive utility D. Evolutionary origins E. All of the above
All 4 levels of analysis are used. They all complement rather than supersede each other. The correct answer is: All of the above
Male Red Backed spiders are dwarfed by their female counterparts. After mating, males will sometimes summersault into the mouth of the mated female where he is devoured. Why has copulatory suicide evolved in redback spiders? Is there a potential cheater problem?
An individual selection hypothesis will best explain why copulatory suicide has evolved in redback spiders (see cheater problem in next question).
Unlike domesticated European bees, African bees are prone to attacking large animals that approach their hives. Even experienced beekeepers have trouble working with African bees safely. African bees were introduced to South America and are rapidly spreading northward and hybridizing with domesticated European bees along the way. The "Africanized" hybrids are almost as aggressive as the fully wild African bees. What is an ultimate explanation for the difference that incorporates both artificial and natural selection?
An ultimate explanation is that high aggressiveness is selectively advantageous in the wild because aggressive workers more effectively repel potential predators from the hive. Domesticated European bees may be more docile than wild African bees because beekeepers destroyed the hives of bees that attacked them, and thereby artificially selected less aggressive bees.
If an adaptation is the product of natural selection, the trait will: Select one: A. Provide a net reproductive gain for individuals that possess the attribute. B. Raise the reproductive success of individuals more than any other alternative that has appeared in the species over evolutionary time. C. Enhance the survival of the fittest individuals in the species. D. Help preserve the species as a whole against the risk of extinction. E. Maximize the survival chances of family members within the species.
B is correct, it is important to remember that adaptations are RELATIVE to other alternatives in the population. A is not necessarily wrong, but it is not the best choice compared to answer B. For C, survival of the fittest is an incorrect measurement of success. The most successful individuals are those that pass on the most genes. For D and E, natural selection acts on the individual level, not the group level. The correct answer is: Raise the reproductive success of individuals more than any other alternative that has appeared in the species over evolutionary time.
Deceptive signaling is widespread in nature with, for example, certain orchids luring pollinator wasps to them with flower petals that smell like receptive female wasps. This case is a Darwinian puzzle because: Select one: A. The proportion of orchid flowers that fruit as result of successful pollination is actually pretty small. B. Natural selection ought to favor discriminating behavior on the part of male wasps so that they do not waste time, energy, and even sperm on orchid flowers. C. Time and energy spent on orchids reduces the capacity of the wasp population to grow, since the deceptive plants slow the ability of male wasps to fertilize all the eggs of their females. D. It is next to impossible to figure out how orchid flowers evolved to smell like the females of certain wasps.
B is the correct answer because it is an individual level selection explanation for why the trait is adaptive. The correct answer is: Natural selection ought to favor discriminating behavior on the part of male wasps so that they do not waste time, energy, and even sperm on orchid flowers.
The group selection hypothesis that lemmings will commit suicide when population densities are high (to leave shelter and food for those who stay behind) is: Select one: A. Likely true, this behavior is adaptive on the individual level. B. Unlikely to be true, distinctive alleles possessed by the suicidal types would be immediately eliminated. C. Unlikely to be true, natural selection favors "for-the-benefit-of-the-group" selection. D. None of the above.
B is the correct answer because only individuals that did NOT commit suicide during times of high population densities would be left and their alleles would predominate in the population. Additionally, natural selection typically trumps "for-the-benefit-of-the-group" selection in causing evolutionary change. The correct answer is: Unlikely to be true, distinctive alleles possessed by the suicidal types would be immediately eliminated.
Kangaroos perceive safety in the open because they can better detect predators and therefore increase their chance of survival.
B, Ultimate. This is the adaptive utility of the trait. The correct answer is: Ultimate
Helpers at the nest receive higher fitness than non-helpers. Select one: A. Proximate B. Ultimate
B, Ultimate. Adaptive utility of the trait. The correct answer is: Ultimate
Meerkat sentinel behavior is a selfish act. Select one: A. Proximate B. Ultimate
B, Ultimate. Adaptive utility of the trait. The correct answer is: Ultimate
Groups of wildebeest that can organize their migration in this manner will eat the most food and eventually produce the most offspring. Select one: A. Proximate B. Ultimate
B, Ultimate. Relative fitness is going to be higher for individuals having this trait. The correct answer is: Ultimate
Male lions kill infants because sexually-selected infanticide is a trait shared with other felids. Select one: A. Proximate B. Ultimate
B, Ultimate. This explains the historical/ evolutionary basis for the trait. The correct answer is: Ultimate
The behavior is the product of a special set of muscle contractions. Select one: A. genetic-developmental B. sensory motor C. evolutionary history D. adaptive value
B, answers how the nervous system detects and affects the behavior. The correct answers are: sensory motor, adaptive value
Males in different populations have song systems in their brains that operate slightly differently. Select one: A. genetic-developmental explanation B. sensory motor explanation C. adaptive value explanation D. relating to evolutionary history
B, explains the physiological mechanism behind the trait. The correct answer is: sensory motor explanation
Wearing expensive and obvious jewelry demonstrates a person's access to resources. Select one: A. Phylogenetic or historical B. Functional advantage or benefit C. Ontogenetic or developmental D. Expression triggering
B, this describes the adaptive utility of wearing expensive jewelry. The correct answer is: Functional advantage or benefit
Young adult white-crowned sparrows are motivated to match their song as closely as possible to that of their neighbors.
B, this provides a psychological explanation for the trait. The correct answer is: sensory motor explanation
All other species in the same genus organize their migration in the same clockwise fashion. Select one: A. Proximate B. Ultimate
B, ultimate. This is a legacy of phylogeny from what a common ancestor did. The correct answer is: Ultimate
Mary does not like dogs because her parents hated dogs and throughout her childhood and always said bad things about them. Select one: A. Phylogenetic or historical B. Functional advantage or benefit C. Ontogenetic or developmental D. Expression triggering
C, Mary's dislike of dogs was shaped during development. The correct answer is: Ontogenetic or developmental
A baby Bieber bird has to hear adult Bieber birds singing in the 1st month of its life in order to learn its species-specific songs. Select one: A. Phylogenetic or historical B. Functional advantage or benefit C. Ontogenetic or developmental D. Expression triggering
C, explains how the trait arose from genetic-developmental mechanisms. The correct answer is: Ontogenetic or developmental
The behavior is a modified version of wing movements that ancestral moths probably used to raise their body temperature in order to begin flying. Select one: A. genetic-developmental B. sensory motor C. evolutionary history D. adaptive value
C, the evolutionary history of the trait. The correct answers are: evolutionary history, adaptive value
The ability to sing the local dialect enables a bird to form bonds with others in the area so that they can adjust their total reproductive output, reducing the risk of local overpopulation. Select one: A. genetic-developmental explanation B. sensory motor explanation C. adaptive value explanation D. relating to evolutionary history
C, this explains how the trait ultimately affects reproductive fitness. The correct answer is: adaptive value explanation
By being able to sing the local dialect, a male is able to communicate territorial ownership of a breeding site to rival males more effectively. Select one: A. genetic-developmental explanation B. sensory motor explanation C. adaptive value explanation D. relating to evolutionary history
C, this explains the current utility of the trait. The correct answer is: adaptive value explanation
A dog makes a better pet if it is raised within a human family. Select one: A. Phylogenetic or historical B. Functional advantage or benefit C. Ontogenetic or developmental D. Expression triggering
C, this insinuates that dogs raised in the wild will not behave as we would want them to as pets. Thus, their pet-like behavior is shaped by genetic-developmental mechanisms. The correct answer is: Ontogenetic or developmental
It is difficult to learn a dialect, which enables females to mate with only those males with good dialects so as to improve the breeding stock of the species. Select one: A. genetic-developmental explanation B. sensory motor explanation C. adaptive value explanation D. relating to evolutionary history
C, this is an ultimate hypothesis that explains utility of the trait. The correct answer is: adaptive value explanation
Most behavioral biologists are skeptical about group-benefit group selection because: Select one: A. This hypothesis is an untested theory for the time being. B. The theory has been proven to be false. C. If hereditary characteristics benefit a group but harm an individual's chances of reproducing, they will be eliminated over time no matter how good they are for the group. D. No one has been able to show how traits that increase a group's chances of surviving could ever spread through a population by group selection.
C. If hereditary characteristics benefit a group but harm an individual's chances of reproducing, they will be eliminated over time no matter how good they are for the group. Individuals who sacrifice their fitness for "the good of the group" will have lower reproductive success than those who act selfishly and will thus eventually be eliminated from the population. Also remember that scientific studies support or negate hypotheses. Theories are not proven one way or the other. (Although most studies do not support this theory)
Starlings sometimes assemble in large flocks that, in the evening, rise up in whirling flight together for 15 or 20 minutes in what looks like some kind of display. Professor Wynne-Edwards has suggested that this behavior is indeed a display that enables individual birds to assess just how many fellow starlings are living in the area so that they can adjust their breeding effort in the upcoming breeding season. In this way, they can avoid producing too many chicks and thereby avoid overpopulating their home range. This a group selectionist hypothesis because: A. The idea is that starlings could evaluate the size of their local population or group. B. The flight behavior of the flock is something that cannot be explained in terms of any benefits to individuals and thus, must be beneficial for the group. C. Starlings do breed in such a manner as to avoid overpopulation. D. The suggestion is that the birds engage in costly behaviors in order to make decisions that are advantageous for other unrelated starlings.
D is true because it highlights an important point about group selection theory, the behavior must appear to be selfless or costly to the reproductive fitness of the individual. For A, the size of the group is irrelevant to group selection theory. For B, group selection hypotheses explain seemingly costly traits as beneficial to the survival of the species. This answer would be a poor explanation for a group selection hypothesis. For C, although this would likely be part of the group selection argument, it does not explain why this behavior would be costly to the individual, which is essential to the group selection theory. The correct answer is: The suggestion is that the birds engage in costly behaviors in order to make decisions that are advantageous for other unrelated starlings.
Wing flipping scares some predators away. Select one: A. genetic-developmental B. sensory motor C. evolutionary history D. adaptive value
D, answers what is the current utility of the trait. The correct answer is: adaptive value
White-crowned sparrows evolved from an ancestral species that possessed the capacity for song learning. Select one: A. genetic-developmental explanation B. sensory motor explanation C. adaptive value explanation D. relating to evolutionary history
D, describes the evolutionary history of the trait. The correct answer is: relating to evolutionary history
Which of the following is NOT a plausible reason for the behavior of an animal to be suboptimal for survival? Select one: A. Evolutionary time lag. B. Sexual selection. C. Developmental constraints. D. The environment recently changed. E. Evolution has stopped.
Evolution is an ongoing process. Additionally, traits that worked well in the past might not be optimal in the newly altered habitat. The correct answer is: Evolution has stopped.
A trait can only be considered an adaptation if it improves the survival chances of an organism. True False
False If a trait increases the life span of an individual but also decreases the reproductive success of that individual then the trait would be selected against because long-lived individuals would fail to pass on their distinctive genes as often as short-lived individuals on average.
Natural selection favors individuals that can survive the best True False
False The problem is possible that there may be a trade-off between survival and reproductive rate such that shorter-lived individuals have the same (or higher) fitness as long-lived individuals.
Natural selection causes individuals to change when they need to adapt to changes in the environment True False
False The problem with the statement is that it suggest that natural selection causes the traits of individuals to change. Natural selection cannot change existing individuals. Populations, not individuals, are what actually evolve. Individuals that happen to have traits that promote reproductive success under changed environmental conditions will leave more descendants, changing the makeup of the population in the future.
Exaptations are evolved traits that, as a result of a changing environment, are no longer adaptive. True False
False This would be an evolutionary time lag.
Descent with modification applies only to large animals and plants and not to smaller organisms like bacteria and protozoans True False
False Descent with modification applies to all living organisms.
Suppose female lizards with reddish throats produce more eggs than females with orangey throats. Why might the females with orangey throats persist in the population, is it possible that the orangey throats are an evolved adaptation? Select one: A. No, because the orangey throats are a byproduct of the need for variation in this species, a critical requirement for the evolution of adaptations by natural selection. B. Yes, because females with orangey throats could still have more offspring that live to reproduce than females with reddish throats. C. No, because there is no guarantee that females with orangey throats are the best for the long-term preservation of this species. D. We cannot tell because we are not told whether reddish females outnumber orangish females in this species.
Fitness is determined by the number of offspring that survive to reproduce. It is possible that females with orangey throats are producing less eggs but a larger proportion of those eggs are surviving. Also remember that natural selection acts on the individual rather than the species. The correct answer is: Yes, because females with orangey throats could still have more offspring that live to reproduce than females with reddish throats.
If a trait has "adaptive value," then it: Select one: A. Enables individuals to adapt to changing environments. B. Confers a reproductive advantage on individuals. C. Has spread because of group selection. D. Must increase the life span of individuals.
Fitness is measured in terms of reproductive success so a trait that increases the survival of an individual's offspring would be considered adaptive. For C, group selected traits can be adaptive however group selection is unlikely to provide the best explanation for an adaptation. For D, all that matters is the number of surviving offspring. If an animal produces 10 offspring and then dies at the age of 2, that animal's fitness is still considered higher than an animal that lives to the age of 20 but only produces 3 offspring. For A, this may be true but fitness is measured in terms of reproductive success so this is not the best answer here. The correct answer is: Confers a reproductive advantage on individuals.
"The activity of N2RB gene declines in older mice and causes a decline in learning ability." Some have suggested that this is beneficial because it means older mice cannot forage as efficiently as they once did, which frees up resources for the next generation. This hypothesis is based on group selection because: Select one: A. The trait of interest is said to have features that reduce the reproductive success of some individuals. B. The trait of interest is said to cause individuals to sacrifice some reproductive opportunities in order to help another generation of mice to grow and reproduce. C. It deals with two populations, older and younger mice, rather than one species as a whole. D. Individuals with this gene have already reproduced.
Group selection hypotheses must involve a trait that appears selfless to benefit the survival of the species as a whole. The correct answer is: The trait of interest is said to cause individuals to sacrifice some reproductive opportunities in order to help another generation of mice to grow and reproduce.
Male Red Backed spiders are dwarfed by their female counterparts. After mating, males will sometimes summersault into the mouth of the mated female where he is devoured. Why has copulatory suicide evolved in redback spiders? Is there a potential cheater problem?
Group selection: reproductive restraint hypothesis - By committing suicide, the males are reducing the overall egg fertilization rate and consequently preventing over-population.
Male Red Backed spiders are dwarfed by their female counterparts. After mating, males will sometimes summersault into the mouth of the mated female where he is devoured. Why has copulatory suicide evolved in redback spiders? Is there a potential cheater problem?
Individual selection: productivity hypothesis - By supplying a free meal, males will facilitate sperm transfer and increase the overall rate of egg production. This will in turn allow populations with suicidal males expand and replace populations without suicidal males.
Which of the following statements about evolution is true? Select one: A. Natural selection cannot change the phenotype of existing individuals. B. Natural selection is a consequence, not a cause, of evolutionary change. C. Natural selection leads to steady progress toward increasingly advanced life forms. D. None of the above.
Natural selection can impact the phenotype of future individuals because only those that survive to reproduce will pass their genes to the next generation. The correct answer is: Natural selection cannot change the phenotype of existing individuals.
Which of the following statements are proximate in nature? Male white-throated sparrows sing in the spring because: That is when their testosterone levels are high. Singing males attract mates in the spring. They learn the song from older males in their neighborhood. Males want to learn the song by listening to others at this time. The ancestors of present-day male white-throated sparrows that sang in the spring had the most descendants.
Proximate explanations explain biological functions in terms of immediate physiological or environmental factors while ultimate explains traits in terms of the evolutionary forces acting on them. Proximate causes answer how the trait arises in development or what triggers the expression of the trait while ultimate causes explain why the trait exists. Option II explains the trait's functional advantage (to attract females and increase reproductive success). Option V answers what the evolutionary history (phylogeny) of the behavior is. The correct answer is: I, III, IV
The hypothesis that lemmings disperse at high population densities for the good of all individuals in a population is what kind of selection hypothesis? Select one: A. Kin selection B. Habitat selection C. Group selection D. Sexual selection E. Survival selection
Remember though that group selection is an unlikely explanation given that the altruistic gene causing them to disperse would usually fail to spread in a population. The correct answer is: Group selection
When sharks attack humans, they often bite the victim once and then swim away. Researcher X argues that sharks rarely eat these unfortunate persons because "sharks prefer the odor and taste of their customary prey, seals and sea lions." Researcher Y disagrees: "Sharks release humans because they are not fat enough, and therefore provide too few calories to be part of the sharks' optimal diet." Using Tinbergen's rules, explain what type of hypothesis each researcher has constructed and explain which is more likely to be correct.
Researcher X has a proximate argument, while researcher Y has an ultimate argument. Such hypotheses are not mutually exclusive; they could both be correct or incorrect, but it's foolish to argue that because X is right, Y is wrong (or vice versa).
Cowbirds are a brood parasite that lays its eggs in the nests of other bird species. The historical range of cowbirds overlaps with robins however due to deforestation, its territory has shifted and now overlaps with sparrows as well. Robins identify and reject cowbird eggs while sparrows will actually give cowbird chicks preferential treatment over their own. What explains the presence of this maladaptive trait?
Since the sparrows do not share a long evolutionary history with cowbirds, they have not had enough time to evolve adaptations that will allow them to differentiate their own eggs from the cowbird eggs. Evolution takes time. When environmental conditions change it takes time for a population to adapt to the new environment. The term "lag" refers to this delay. The correct answer is: Evolutionary lag time
Lemmings leave where they are living when population densities get very high because the risk of inbreeding increases at high population densities, which favors males and females that disperse to find genetically dissimilar mates in other areas.
The lemmings in this scenario are making decisions motivated by their individual reproductive potential. The correct answer is: for Darwinian natural selectionist hypothesis
Lemmings leave where they are living when population densities get very high because they have better chances of reproducing in places where the population density is lower. Select one: A. for group selectionist hypothesis B. for Darwinian natural selectionist hypothesis C. for other
The lemmings in this scenario are making decisions motivated by their individual reproductive potential. The correct answer is: for Darwinian natural selectionist hypothesis
Unlike domesticated European bees, African bees are prone to attacking large animals that approach their hives. Even experienced beekeepers have trouble working with African bees safely. African bees were introduced to South America and are rapidly spreading northward and hybridizing with domesticated European bees along the way. The "Africanized" hybrids are almost as aggressive as the fully wild African bees. Explain why it would be impossible to devise an experiment to distinguish between your proximate and ultimate hypotheses.
The proximate hypothesis tries to explain how the bees differ physiologically whereas the ultimate hypothesis tries to explain why the physiological difference evolved. It would be illogical (as well as impossible) to attempt to distinguish between them because they answer two different questions.
Lemmings leave where they are living when population densities get very high because as the dispersing lemmings die off, they leave the species in the hands of the best survivors, which enables selection to work, resulting in a more adapted lemming species as a whole A. for group selectionist hypothesis B. for Darwinian natural selectionist hypothesis C. for other
This is group selection because the scenario assumes the dispersing lemmings are leaving to ensure the survival of the remaining population. The correct answer is: for group selectionist hypothesis
Lemmings leave where they are living when population densities get very high because high densities threaten the survival of the local population, which favors a reduction in the number of lemmings present there. Select one: A. for group selectionist hypothesis B. for Darwinian natural selectionist hypothesis C. for other
This is group selection because the scenario assumes the dispersing lemmings are leaving to ensure the survival of the remaining population. The correct answer is: for group selectionist hypothesis
Lemmings leave where they are living when population densities get very high because the fighting that takes place at high densities threatens to injure the males and females of highest genetic quality, which is harmful to the gene pool.
This is group selection because the scenario assumes the dispersing lemmings are leaving to ensure the survival of the remaining population. The correct answer is: for group selectionist hypothesis
The island of Mauritius was colonized by Dutch sailors in the 1600s. Large endemic fruit-eating animals were rapidly driven to extinction by the settlers. Why might a number of tree species here continue to produce fruits that are best suited for consumption by large herbivores as a means of seed dispersal? What is this an example of and why might this be the case?
This is likely an example of an evolutionary time lag where anthropogenic forces such as climate change, hunting pressures, or nearby land-use change have resulted in rapid removal of large frugivorous species in the area. The tree species are experiencing an evolutionary lag time because they have not had enough time for adaptations favoring smaller fruits to spread in the population and are thus exhibiting characteristics that are now suboptimal in their altered environment. Unless conservation efforts are made to restore populations of large frugivores, this is an example of an extinction debt.
Unlike domesticated European bees, African bees are prone to attacking large animals that approach their hives. Even experienced beekeepers have trouble working with African bees safely. African bees were introduced to South America and are rapidly spreading northward and hybridizing with domesticated European bees along the way. The "Africanized" hybrids are almost as aggressive as the fully wild African bees. Describe an experiment that would demonstrate whether the behavioral difference between European and African bees is due, in part, to genetic differences between them.
Transfer African bee eggs into European bee nests and vice versa. If behavioral differences persist in cross-fostered workers, the differences must be partly genetic.
Natural selection theory provides a mean for why some changes spread through a species while others did not. True False
True If an adaptation contributes to higher reproductive fitness than an alternative trait, then that trait will spread through the population.
Adaptations depend on the presence of others in a population True False
True - Fitness benefits of adaptations are relative to the fitness of others in a population.
What is one possible ultimate explanation for the question, why do all male songbirds in a population learn to sing the same song? Select one: A. Young males have the genetic predisposition to learn the species typical song from older male tutors in the neighborhood B. Males who sing the local dialect are more successful at defending their territory and attracting mates C. All males in the same population develop the same complex neural system controlling song learning D. A & C
Ultimate explanations in the functional category have to do with the adaptive value of traits. The adaptive value of a trait refers to how the trait influences survival or reproduction. A is proximate, where the males LEARN the song from other individuals. C is also proximate, describing an internal state (brain structure). The correct answer is: Males who sing the local dialect are more successful at defending their territory and attracting mates
Male Red Backed spiders are dwarfed by their female counterparts. After mating, males will sometimes summersault into the mouth of the mated female where he is devoured. Why has copulatory suicide evolved in redback spiders? Is there a potential cheater problem? Is there a potential cheater problem? Explain.
Yes. Cheater problem: If non-suicidal males fertilized more eggs than suicidal males, then suicidal populations would rapidly be taken over by non-suicidal genotypes (within populations)
The Hoatzin is a peculiar bird species that has an extra set of claws on its wings (as pictured below). How could we test if this unique trait is adaptive in its current environment? What measurement would tell us that this is adaptive?
You would have to measure the fitness (reproductive success) of chicks with varying claw lengths or presence/absence of claws. There are a variety of ways we could test this including: Compare the fitness of naturally-occurring variation. Do chicks with large claws do better than chicks with small claws? If so, having large claws may allow chicks to better defend themselves or evade predators. Remove the extra claws from some chicks and see if clawless chicks are still able to live to produce the same number of offspring.
What is the ultimate fitness effect of dispersal in juvenile male Belding's ground squirrels? Select one: A. Males who disperse attain a higher body mass. B. Males who disperse are more curious, less fearful, and more active. C. Males who disperse reduce the chances of incest. D. Males who disperse mate with higher quality females. E. None of the above.
Your answer is incorrect. The correct answer is: Males who disperse reduce the chances of incest.
