Life history evolution Flashcards
What is a trade off?
Losing one quality for the gain of another.
What is genomic imprinting?
The idea that genes may only be switched on if they are inherited by a particular parent. The gene expression is silenced by methylation by one parent.
How does genomic imprinting relate to evolution?
The idea that father’s genes are primted so that the child will remove as many resources from the mother as possible, whereas the mothers genes are primed to have an optimal giving of genes over a lifetime rather than all at once.
What is the example with mammal embryo growth relating to genomic imprinting?
The a mother may silence a growth-promoting gene, whereas a father will silence a growth-inhibiting gene.
What is natural selection expected to do in light of life history traits and trade offs?
Maximise the number of offspring surviving to maturity. Life history strategies are unique to each species.
How does when a deleterious mutation act affects whether it will be passed on or not?
If a mutation shows before the organism has offspring, the lineage will be gone so the mutation will not be passed on - it will cause harm before the organism can breed. If the mutation occurs after reproductive age, the individual will still be able to reproduce and pass on the deleterious mutation.
What is one theory as to why people think we age?
The accumulation of deleterious mutations (this is called mutation accumulation)
What is another theory as to why we age?
The antagonistic pleiotropy theory. This is the idea that the accumulation of random, germline mutations of a kind that are beneficial early but detrimental later.
What do both theories of ageing predict?
A higher extrinsic mortality will select for shorter life (by increasing the accumulation of late-acting deleterious mutations) and that we should expect to find trad-offs between fitness traits expressed at different ages.
What was found with guppies?
That guppies in areas of high predation had evolved to produce many small offspring and that males had evolved to be less attractive (smaller and less mature) to predators.
What is the trade-off observed in lizards and the evidence for this?
There is a trade off between offspring and size. If the lizards were stopped from reproducing they were seen to grow twice as big.
When do trade-offs arise?
When investment in one trait results in lower investment in another trait.
What are the different types of survivorship curve?
Type I: High juvenile and adult survival, Type II: Same survival rate for both, Type III: low juvenile survival and high adult survival.
What is a reproductive table?
It shows the reproductive rates of a population, summarized by specific age categories.
What can a reproductive table reveal?
The most fecund age periods, the generation time (average internal between birth of an individual and its offspring) and fertility schedules.
