Evolution and genetics Task 4: The problem of cooperation
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Course
Evolution And Genetics (IPN1030)
Institution
Maastricht University (UM)
It is the summary of Task 4.
It has all the notes from the mandatory literature textbook (Nettle)
It also includes the summary of the mandatory articles:
1) Scott-Phillips, T. C., Dickins, T. E., & West, S. A. (2011). Evolutionary theory and the ultimate–proximate distinction in the hum...
4) Shape of adaptive landscape. Conditions to reach optimal design:
o Must be continuous series of intermediate phenotypes in between
o At every point in the series, successor eye type must have caused higher fitness than
its predecessor. If not, they are stuck on a local peak where all new alterations have
to be worse in order to get to the optimal design
4) Trade off points: the point of having both trades that are contradictory
to each other in their optimal level.
A genetic Correlation: Selecting for one trait changes the population average of the other
traits as well.
- Species boundaries are the outcome of evolutionary processes such as extinction,
adaptation, and drift
- Mutation is governed only by biochemical processes within the cell. It is completely
random with respect to the phenotypic effects that it produces.
The Evolution of Anisogamy:
Isogamous reproduction: Half half genetic share in the offspring
Anisogamous reproduction:
- the female gets a half share and pays almost all the costs
- Common in multicellular organisms
- More energy required to produce larger-sized gametes (male gametes are much smaller
than female gametes)
Sexual Dimorphism: the difference between male and female forms of the same species.
Bateman’s Principle: Male reproductive success increases with each additional partner mated
to a greater extent that it is true for females.
- Males should always seek and take any extra mating available (since the cost is low and
the benefit is high), whereas females should be choosier.
- The benefit of an extra mating is greater for a male than for a female: however, it
doesn’t state that there is no benefit for the female at all.
Why do females like fancy males?
A) The Sexy Son Hypothesis:
If there is any initial slight preference amongst females for males with longer tails, than the
preference for long tail and the length of the tail itself co-evolve to both become ever greater
over time.
Ex> females choose long tail males, produce offspring that have long tails > same process
continues.
, B) The Good Gene Hypothesis:
The males who are proving that they have the high quality to do well in the current
environment get chosen, which indicated good genes.
- Both hypotheses are likely to operate. Choosing a male who is signaling good genes will
benefit a female both through making her offspring healthier in general and making her
sons more attractive to females in particular.
Extra-pair matings: Matings that take place with another male other than the social partner
The offspring resulting from an extra-pair copulation are more likely to survive than their
nest mates fathered by the social partner. Thus, females are using extra pair mating to choose
good genes.
- Males often have secondary tactics for gaining some mating of they are not doing well
in the primary competition.
Mate choice in Humans:
- Males are around 10% bigger than females, more aggressive compared to women >
looks for physical appearance
- Choosy females > looks for wealth
, Ridler:
- Sex ratio is 50:50
- It is an equilibrium point: if a population ever comes to deviate from it, natural selection
will deviate it back
- Individual selection favors a 50 : 50 sex ratio unaffected by sex differences in adult
mortality
- Theory predicts deviations from 50 : 50 sex ratios in certain special cases
- Seychelles warblers produce more sons in some conditions, and more daughters in
others
In summary, when one gender of offspring enhance parental reproduction, natural selection
favors parents who produce more offspring of that gender. When one off- spring gender
reduces parental reproduction, natural selection favors parents who pro- duce less of that
gender. Both these predictions have been successfully tested in the Seychelles warbler.
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