Evolution Ch 12
Why does menopause occur?
-risk of childbirth increases with age -remaining fertile can detract from investing in current offspring -older mothers are likely to die before offspring reach independence -grandmother effect
What is genomic imprinting?
Genomic imprinting refers to different expression of a gene depending on whether it was inherited from the male parent or the female parent.
What is senescence?
The gradual decline of all organ systems, leading inevitably to death
What is IGF2 gene?
a growth hormone gene
what is IGF2r
a growth inhibiting gene
to make a mule we must use what
a male donkey and a female horse
why does natural selection favor antagonistic pleiotropy?
because organisms can reproduce earlier in life
what happens as animals get older?
cells accumulate malformed proteins, immune system becomes less effective, cancer goes up
What is intralocus sexual conflict?
conflict between the fitness effects of alleles of a given locus on males and females
what is the parent of origin effect?
describes an effect on the phenotype of an offspring caused by an allele inherited from a particular parent
what can bring about rapid evolution of life history traits?
environmental change
what happens if the OSR is unbiased?
females and males will spend near equal time with offspring and sexual selection will be much weaker
what happens if the osr is female based?
females fight for access to males
what sex normally has an active copy of IGF2
males
why do scientist think senescence has evolved?
natural selection has selected alleles that enhance growth and reproduction early in life
what are examples of life history traits?
organisms age at first reproduction, the duration of reproduction, the # and size of offspring produced in a population
what is the limit of self repair?
our bodies require continual repair so natural selection favors levels of repair that are good enough to keep an organism in sound condition only for as long as it has a reasonable chance for reproducing
What is the Trivers-Willard hypothesis?
predicts greater investment in male offspring by a female in good condition and greater investment in female offspring if the female is in poor condition
what is frequency dependent selection?
the fitness of a phenotype depends on how common it is in the population, this maintains variation within populations
what happens if the females copy of iGF2r is disabled?
the mouse is born very large
what happens if the males copy of IGF2r is disabled?
the mouse is large if the mothers copy is also disabled
in guppie populations without predators what do the offspring look like?
the offspring are larger but less are produced
What is life history?
the pattern of investment an organism males in growth and reproduction
what is antagonistic pleiotropy?
the theory that some animals posses genes that help them in early life but harm them in later life
What is the p53 gene?
tumor suppressor gene, helps prevent tumors in early life but can be harmful later in life
When do trade-offs occur?
when investment in one trait results in lower investment of another trait
what is parental-offspring conflict?
when parents benefit from withholding resources from some offspring and giving it to others
what is parental conflict?
when parents have an evolutionary conflict of interest over the optimal strategy for parental care
sex ratio in seychelles warblers
with high resources, females favored (up to 3) with low resources, males favored (disperse away from poor habitat)
