Dawkins quiz
Use Hamilton's rule to express the area where mothers and progeny are in conflict. ***
(Relatedness of mother and progeny)X(Benefit to Progeny) < (cost to mother) In the case of mothers and progeny, conflict arises over resource allocation. Mothers have a limited amount of resources to allocate among their progeny. Progeny, on the other hand, seek to maximize their share of resources to enhance their own fitness.
What sorts of males should females avoid mating with?
- Avoid males that aren't sexually attractive - lessons the chance that their offspring will be sexually attractive and pass on her genes - Avoid mating with males from closely related species - offspring may be hybrid and thus infertile - even if the child itself is viable - Females should avoid mating with males who tend to be promiscuous / don't show long term fidelity characteristics
What is wrong with Alexander's argument about parental control? When are parents likely to win?****
Alexander is wrong because he assumes a false asymmetry in the parent child relationship. You could easily reverse his logic and say that parents have a gene that tends to cause equal distribution, but at some point the parent was a child. So, that gene would have hurt it when it was a child, and the gene cannot be successful. Not sure when parents are likely to win.
When are eggs recognized and when not? *****
Egg recognition in birds and other species typically evolves in response to brood parasitism. Species at risk of raising offspring from parasitic eggs develop the ability to distinguish their own eggs from others. In species where brood parasitism is unlikely, such as those in isolated environments or where nests are spread apart, egg recognition is less developed, as the risk of accidental egg mixing is minimal.
If siblings are related to each other why should they be in conflict?
Even though all siblings have the same relatedness to each other, they have one hundred percent relatedness to themselves. They are still related to their siblings, so they want the mother to invents in them too. But they will always favor themselves over their siblings.
Why do fish school? Give two different reasons.
Hydrodynamic advantage for the fish in the herd from the turbulence produced by the fish in front (however, there is a disadvantage for the leading fish) If fish are being hunted by a predator that tends to attack the nearest prey, each prey will constantly try to avoid being the nearest to a predator. Fish will therefore school to avoid being on the edge/boundary of the school and increase their distance from a predator
What is natural selection?
Natural selection is the differential survival and reproduction of genes/ individuals due to differences in phenotype. While for a species, it is beneficial to have some altruistic individuals who are willing to sacrifice themselves for the good of their group, natural selection also refers to the fact that if there is one selfish individual who is ready to exploit the altruism of the rest, then he, by definition is more likely to survive and have children. (7-8)
Outline the evolutionary argument for senescence.
Senile decay/senescence is a result of accumulation of late-acting lethal/semi-lethal genes in the gene pool. Such genes are favored by natural selection as individuals with late-acting lethal genes may still be able to produce/have more time to reproduce, while early-acting lethal gene individuals cannot/do not. As a result, natural selection will favor genes that postpone the effect of lethal genes and favor genes that hasten the effect of good genes.
Use Hamilton's rule to express the area where siblings are in conflict with each other.
Siblings are ½ related to each other, and 1/1 related to themselves. So, a sibling will lie and cheat other siblings out of parental investment up to the point that the loss from their siblings is equal to twice their gain.
What is a conditional strategy?
A behavioral strategy where an individual's response depends on the strategy of its opponent. Examples include the Retaliator, Bully, and Prober-Retaliator. This approach allows an organism to adapt its behavior dynamically, based on the actions of others, enhancing its survival and reproductive success in varying social and environmental contexts.
What is the handicap hypothesis?
A gene that leads males to develop a handicap - large tails or antlers- becomes more numerous in the gene pool because females choose these traits as it's a sign of strength that they can survive despite having these handicaps. These good 'other' genes will benefit their kids as they are 1. Strong/healthy 2. Have the sign that shows that they are strong and 3// their children will have the genes to choose handicapped males. Handicapped phenotypes are only seen in males and thus the preference gene will be passed on to the daughters. Contradiction - If the handicap hurts the individual - it will penalize the offspring just as surely as it may attract females. CANNOT BE PASSED ONTO DAUGHTER
Why and when should a mother have favorites? Is a short-lived mother more or less likely to have favorites than is a long-lived mother?
A mother should have favorites when her children are not all perfectly equal. This is a benefit to herself because she can devote more resources to children more likely to survive and spread her genes. A short lived mother would be more willing to have favorites because her time left might not be enough to gather enough resources for all the children to survive.
Why do plasmid genes share fewer interests with nuclear genes than nuclear genes share among themselves?
A plasmid is capable of splicing itself into a chromosome and therefore can be transmitted without sexual reproduction. Thus, a plasmid does not care about maximizing sexual reproduction. Nuclear genes require sexual production to be transmitted, and so will operate to increase the likelihood of being passed on. For example, the virus causes us to sneeze or cough, helping it travel from one host to another. For the nuclear gene, the interest lies in sexual reproduction.
What is an evolutionarily stable strategy?
An evolutionarily stable strategy is a strategy that when adopted by most of the members of a species, cannot be beaten by an alternate strategy. So, once the strategy has been established, anyone straying from it will be punished.
What do aphids do that armadillos don't? Why?
Aphids display altruism through genetically identical clones, with some acting as sterile soldiers to protect others, a behavior driven by kin selection. Armadillos, although they produce identical quadruplets, do not exhibit this level of altruistic behavior. This difference highlights distinct evolutionary strategies in these species.
If one parent deserts should the other stay and rear the babies? Why or why not?
Assume the deserted female cannot fool a new male a new male into adopting her child - If the child is old - may pay to stick it out /already had a lot invested and less work than to restart - But if they are young kids - then the babies are certain to die. They are forced to take a drastic approach in order to salvage the resources they already invested into the child. - A reasonable policy for a female who is in danger of being deserted might be to walk out on the male before he walks out on her, because in this can force the second partner into the more drastic decision. Genes for deserting first could be favorably selected simply because genes for deserting second would not be.
If hawk and dove coexist at an ESS what would have higher fitness, a new baby with hawk or dove genotype? Discuss. *****
At an Evolutionarily Stable Strategy (ESS) where Hawk and Dove coexist, the fitness of a newborn with a Hawk or Dove genotype depends on the current ratio of Hawks to Doves in the population. If there are many Hawks, a Dove may have higher fitness due to less risk of injury. Conversely, if there are many Doves, a Hawk may have higher fitness due to reduced competition for resources. The fitness advantage shifts based on the population composition of the two strategies. (both equilibirum in population - competion in the group )
Why do female mice evolve to abort when they smell a new male?
Brue effect: male mice secrete a chemical which when smelt by a pregnant female can cause her to abort. She only aborts if the smell is different from that of her former mate. In this way a male mouse destroys potential step children - and render his new wife receptive to his own sexual advances. Population control mechanism! This is also seen in male lions and infanticide
Why would a bird ever feed anyone in a different nest?
Dawkins suggests that cuckoo's are like a mind-altering drug to bird parents of different species: they are unable to resist it when they see it. irresitable theory - a bird sees a crying cuckoo and their nervous system tells them to feed
How do cuckoos get away with their parasitism?
Cuckoos exploit the paternal instincts of other birds because in general, birds will be nice to small birds in their nest and/or may not recognize the egg . They also lay eggs that may imitate the color, shape, and size of the host species.
When will hawks not drive doves to extinction?*****
Doves are unlikely to be driven to extinction by Hawks in a predominantly Hawk population because a Dove will always avoid injury by not engaging in fights, whereas in every Hawk-Hawk encounter, one Hawk gets injured. This relative safety of Doves means their genes can continue to spread, as they avoid the cost of injury that Hawks face.
How do genes influence behavior?
Genes do not influence behavior directly; instead, they are like computer programmer and preset their survival machines beforehand. Then the machine is on its own. They are unable to "take the reins" because of a time lag in their actions. They can build proteins, but that process is much slower than the time needed to quickly react to something. They instead act on predictions; for example, they "know" that polar bears live in the cold, so they will give cubs thick skin and fur. They aren't doing this because they are thinking about it, but instead because that is what they have always done, and that led to their survival.
Compare egg recognition in gulls and guillemots.
Gulls do not recognize eggs because it is very improbable for a gull egg to move from one next to another since they are far away and high up. However, Guillemots do recognize eggs because their eggs can easily roll around to nearby nests.
What sorts of behavioral information would you want about a parasite to predict its impact on its host's behavior?
How the parasite propagates its own genes - does the host's drive to reproduce also serve to benefit the parasite's gene propagation? If the parasite does not use the host's reproduction to propagate its genes and instead merely siphons resources from its host, then it will act to reduce the host's drive to reproduce and increase the host's motivation to ensure its own survival. P. 316: "The key point is that a parasite whose genes aspire to the same destiny as the genes of its host shares all the interests of its host and will eventually cease to act parasitically."
What are the similarities and differences in selection in a pack of wolves and a honeybee colony?
In a pack of wolves, each individual will act in the interest of propagating its own genes, because they do not share 100% of their genes with any other individual in the pack. A honeybee colony acts like a "superorganism," where there are sterile workers who act in the interest of the queen's reproduction, because she produces offspring that are genetically related to each worker. The success of the cytoplasmic genes is not contingent on the success of the nuclear genes since they are separate. Nuclear genes need the other genes in the individual to be successful or else even the successful genes will not be passed on.
When would a young animal prefer to die than to increase risk to siblings?
It would rather die when the increase in risk is disproportional to the relatedness to its siblings.
What is the Lack hypothesis? Why was David Lack so important in early thinking about selfish genes?
Lack hypothesized that for any given species, in any given environmental situation, there must be an optimal clutch size. Each selfish individual chooses the clutch size that maximizes the number of children she rears. This is important because it rejects theories that clutch sizes are based on altruistic tendencies. They are not practicing birth control for the sake of the group's resources, they are practicing birth control to maximize the amount of surviving children.
What is the difference between investment in males and females, and numbers of males and females? *****
Males put in less investment because they produce many sperm and can impregnate many females at the same time. Females however are more limited in the number of children they can bear. numbers of males and females" refers to the actual count or ratio of individuals of each sex within a population.
In what sense are ornaments handicaps?
Ornaments are handicaps because as much as they attract potential mates, they also attract predators/can also just weight down males in everyday life
How does parental care influence the sex ratio?****
Parental care influences sex ratios depending on how much they invest in each sex. Individuals have no control over the actual amount of sons and daughters they produce. Normally a parent should invest equally, and thus the ratio is 1:1. The sex ratio can change based on parental investment - but only if investment on the child were proportional to sex ratio. 1 son:3 daughtesr - the son would need to be SUPER and have 3x the resources Other examples: elephant seals, a policy of having three times as many daughters as sons, but of making each son a supermale by investing three times as much food and other resources in him, could be stable. - There could be unequal sex ratios that were evolutionarily stable, provided correspondingly unequal amounts of resources were invested in sons and daughters. We see a 1:1 ratio despite most males not being able to reproduce. if there are more females then males would have an advantage if there were more males - female have more advantage. thus 1:1 is an ESS parents should invest 1: 1- meaning that there would be equal males and feamels. sometimes depending on environment and conditions will change but should be equal
Why do lower-ranking individuals have a lower chance of reproducing?
Wynne-Edwards believes that higher ranking individuals have a larger chance to reproducing than lower ranking individuals. This is either because they are preferred by females or physically can prevent the lower ranking individuals from breeding.
What are the pros and cons of an adult male baboon defending babies against a leopard?
Pros: - Genetic Investment: Defending related babies helps ensure the survival of his own genes (kin selection). - Increased Social Status: Success in defense can boost his status, leading to more mating opportunities. Cons: -Risk of Injury or Death: Defending against a leopard is dangerous and could be fatal. -Energy and Resource Costs: The effort requires significant energy, which could be used elsewhere. -Opportunity Cost: Time spent defending might detract from his own reproductive opportunities.
Exactly how can long tails evolve through the process of runaway selection?
Runaway selection: rapid evolution of specific physical traits in male animals - so strongly preferred by females of certain species that they are only male with those males who have the STRONGEST expression of the trait. Continues to pass on many generations - and the species will have extreme sexual dimorphism. Sexually attractive traits which are indicators of genetic superiority, like long tails in some birds, will continue to become more extreme due to strong selection for them (females penalized if she did not choose long tailed, because sons would not mate as well) until the trait actually poses negative consequences on an individual that are greater than the benefits of the sexual attractiveness.
Are runts evolved, or developmental accidents? Why or why not?
Runts are evolved. When uncertain of optimal clutch size, a mother might bear one more child than necessary. In the case that it is bad year, they mother will simply devote less resource to the smallest child, and it will eventually die and become food. This is the runt, and it is the result of the mother hedging her bets on whether the year will be good or not.
Why don't slave making ants have female biased sex ratios?
Slave ants have genes to promote a 3:1 ratio in their colony but not in the new colony they found themselves in. Also, they do not have the genes to combat the queen's techniques for a 1:1 ratio. The slaves are ignorant of the fact that they are unrelated to the queen, and the queen of the slave-making species is in a position to bend the sex ratio in the direction she prefers. The slaves hold the power over the queen's own true-born children, and the slaves think they are looking after their own siblings and doing what would be appropriate in their own nests to achieve the desired 3:1 bias in favor of sisters. However, the queen is able to get away with counter measures and there is no selection operating on the slaves to neutralize these counter measures since the slaves are totally unrelated to the brood. The queen of a slave-making species can get away with changing the genetic code freely without any danger that genes for breaking the code will be propagated to the next generation, and as a result, we expect the ratio of investment of reproductives of the two sexes to approach 1:1 Slave-making ants have evolved to focus their resources on producing and maintaining a workforce of workers rather than reproductive individuals By maintaining a balanced sex ratio, they ensure that they have enough worker ants to carry out the various tasks required for colony survival, including raiding and caring for captured brood.
Why are social hymenoptera sisters related by 0.75?
The sperm that created them are identical in every gene since all males have only one set of genes. So, the paternal genes are all the same, and there is a one half chance that a gene in one from the mother is also in the other. So they are ½ + ¼ related. Hymenoptera nest has only one mature queen, and she makes one mating flight when young and stores up sperm for the rest of her life Not all eggs are fertilized: these develop into males which only have one set of chromosomes Females have a double set of chromosomes, including the genes for worker-making and queen-making Full sisters not only share the same father: the two sperms that conceived them were identical in every gene. The sisters are therefore equivalent to identical twins as far as their paternal genes are concerned. If one female has a gene A, she must have got it from either her father or her mother. If she got it from her mother then there is a 50 percent chance that her sister shares it. But if she got it from her father, the chances are 100 per cent that her sister shares it. Therefore the relatedness between hymenopteran full sisters is not 0.5 as it would be for normal sexual animals, but is 0.75
Why is meiotic drive such as is caused by t alleles in mice against the interests of most of the genome?
The t alleles are mitotic drive genes and affect the odds of being selected in meiosis heavily in their favor instead of being half and half. So, they spread quickly throughout the population, but when someone inherits two copies of the allele, they either die or become sterile. This is disastrous for all the other genes because they cannot be passed on.
Why might queens of honeybees mate multiply, thereby 'throwing away' the haplodiploid advantage?
Then they will be more related to each child in proportion to their relatedness to the male so that they can bias the sex ratio in their favor. Similar to social hymenoptera (see above), 75% related to each other as opposed to expected 50%. Honeybee queens have the unique ability to mate with multiple drones during their mating flights, which can result in a colony having a genetically diverse population of workers. This behavior, known as polyandry, does indeed seem to "throw away" the potential haplodiploid advantage that comes with the bees' genetic system. Haplodiploidy is a genetic system where females develop from fertilized eggs (diploid) and males develop from unfertilized eggs (haploid).
Why should an individual refrain from a fight to the death?
There are both benefits and costs to killing a rival. First, it expends a lot of energy and time and could potentially lead to injury. Also each species is not isolated into two survival machines in direct competition. There is a large pool, so by taking the time to remove one rival, another member in the pool could also be benefiting more than oneself without having to waste the resources.
Who wins parent-offspring conflict and why? What are the important variables?
There will always be a compromise in this conflict between the ideal situation of the child and what the parent desires. The important variables are how good the parent can read the child's behavior, and how good the child and deceive the parent.
When are fights to the death most likely to occur?
They occur when the benefits of winning are so great that they outweigh the potential of death. Asymmetrical fitness - potential gain n reproductive success for one individual greatly outweighs the risks involved
When do animals reduce their clutch size? Which babies are they likely to remove, largest or smallest?
They reduce their clutch size if they estimate the population to be large, which would make it difficult to support more babies. Smaller babies are more likely to be removed since they require more help and resources to grow to be as healthy as the others.
How might we distinguish the runaway selection process from the handicap process?
This theory says that eventually with one sex preferring a certain trait of another, there will be an unstable runaway process where that trait is extremely exaggerated over time. Runaway selection -natural selection keeps selecting for a trait and shifts average (increase gene freq.) Handicap - trait is selected despite its negative effect to show organism survives despite it. involve the evolution of exaggerated traits in mate selection, runaway selection emphasizes mate preference driving the evolution of traits, whereas the handicap principle focuses on the idea that traits are signals of an individual's genetic quality because only high-quality individuals can afford the costs associated with those traits.
What is wrong with the argument that traits evolve for the good of the group or the species?
Traits do not evolve for the good of the group as group selection favors the survival of selfish individuals. In a group of altruists, selfish individuals benefit from exploiting the rest of the group and pass on more of their selfish genes, leading to more selfish individuals. Even if selfish individuals never evolved out of a purely altruist group, selfish individuals would migrate and produce the same result. Foresight would allow individuals in a group to see that their own interests are those of the group and in opposition to their selfish greed, as the extinction of the group would be their own extinction. However, evolution is blind to the future and selects for selfish individuals that benefit in the short term (8).
How can grouping in the absence of kin selection be advantageous?
Utilize skills of each other to compensate for weaknesses. Can help with predation. predators are known to go for odd men outs. We have already agreed that staying in one large group is better than being alone. So, when faced with danger even though it is best to run as fast as possible, it could be dangerous since then you would be alone. So, the best strategy would be to run away together as a pack to avoid being alone but also avoid staying.
What is Fisher's argument for equal investment in the sexes?
We see a 1:1 ratio despite most males not being able to reproduce. if there are more females then males would have an advantage if there were more males - female have more advantage. thus 1:1 is an ESS parents should invest 1: 1- meaning that there would be equal males and feamels. sometimes depending on environment and conditions will change but should be equal
What factors might favor producing fewer eggs than one could rear to independence?
When food and resources are limiting factors, it is more favorable to focus these resources on fewer eggs so they have a higher chance of being reared to independence. According to the Lack theory, natural selection adjusts the initial clutch size to make the most of these limited resources.
What are the evolutionary costs and benefits of sex.
con: only passes on half of the genes pro: accumulate in a single individual of advantageous mutations which arose separately in different individuals. gene pool is kept will stirred - and the genes partially shuffled Sex is an inefficient way of propagating one's genes since it only takes half and mixes them with another half without any guarantee that the good genes will stay and the bad ones will go. There are group level benefits of sex, which facilitates the accumulation in one person of good genes that arose in different individuals.
Does evolution work more rapidly between competing groups or between competing individuals?
evolution works more rapidly between competing individuals because selfish individuals can take advantage of altruism among the population. Group selection/extinction is much slower of a process that individual competition, so evolution works more rapidly between competing individuals.
Why do flukes cause snails to produce thicker snail shells?
shell thickens in response to fluke - the thickening increases survival. But it requires a lot of resources - thus it doesn't happen without being provoked. They could spend this time/enery. on reproduction A thicker shell is only beneficial to the snail when the fluke bears the economic cost of thickening the shell. big idea is it increases survival but doesn too anything for the genes - its a plastic effect A thicker shell may prolong the life of the snail, but does not help the snail's genes. Bodily survival does not equal reproduction.
