Chapter 2 Flashcards
How do social insects operate? (3)
in colonies
one queen who lays all the eggs
sterile castes that do not reproduce
What is altruism?
self-sacrifice/ work for the benefit of the colony
What is intelligent design? (2)
idea that a higher power is in control, due to the complexity of nature (like social insects)
supports that working together to maximize success, like a watch
How was intelligent design disbunked?
“The Blind Watchmaker” by Dawkin
What is group selection (2), and who coined it?
first theory of altruism, all social behaviors evolved to benefit the group or species as a whole
altruists are more likely to survive
Wynne Edwards
What did group selection suggest in birds?
nonterritorial birds were holding back to avoid food depletion
What did George C. Williams do for group selection?
challenged group selection, showed genes and hereditary traits that were determined by reproductive success of individuals, not the groups
How did hanuman langurs disprove group selection? (2)
no-nkillers would live longer (not risk their lives from the protective mothers), and reproduced more, infanticide wouldn’t persist
if group selection favored a trait involving reproductive self-sacrifice, but natural selection works against it, natural selection trumps group selection
How did lemmings disprove group selection
lemmings won’t commit suicide for the group, as cheaters will evolve and take over
What did Richard Hamilton come up with?
personal reproduction is direct contribution to reproductive output, but helping genetically similar individuals (non-descendent relatives) can provide an indirect route to furthering your genes into future generations
What is coefficient of relatedness?
probability than an allele in one individual is present in another, because both individuals inherit it from a recent common ancestor
What is the relatedness between parent and offspring?
50% (50% chance of inheriting one allele from a parent)
How related is a woman to her child? her niece? her cousin?
child- 0.5
niece- 0.25
cousin- 1/8
How is altruism adaptive?
increased chance of relatedness; if allele in question was the “altruism allele”, there would be a higher chance of it being passed on
What is fitness?
number of genes contributed to the next generation
What is direct selection?
when hereditarily distinct individuals differ in the number of surviving offspring they produce, or the number of genes passed on to subsequent generations
What is indirect selection?
when hereditarily different individuals differ in the number of non-descendant relatives they help to survive to reproduce
What is direct fitness?
measure of reproductive or genetic success of an individual based upon the number of its offspring that survive to reproduce
What is indirect fitness?
a measure of the genetic success of an altruistic individual based on the number of relatives that the altruist helps reproduce that would otherwise not survived to do so
What is inclusive fitness?
a total measure of an individual’s contribution of genes to the next generation by both direct and indirect fitness
What is hamilton’s rule, and what does it mean?
altruism gene will spread only if indirect fitness gained > direct fitness lost
only if rbB > rcC
- B= number of relatives existing because of altruist
- rb= relatedness between altruist and relative
- C= number of offspring not produced by altruist
- rc= relatedness between parent and offspring
What are two important traits for social insects, and why?
monogamy - important for the evolution of eusociality in hymenopeterans; if queens mated multiple times, daughters would have a lower relatedness
haplodiploidy- important for the evolution of this system
Why are social insects viable?
workers need only a small indirect fitness advantage for helping siblings survive for this to be adaptive
How related are female sterile workers in social insects?
sisters have a 75% relatedness, while brothers have only 25% (3:1 ratio)
