BIOL 105 Lecture Notes - Lecture 15: Guppy, Mutation Rate, Pleiotropy
Document Summary
Variation in life history - life span & senescence: 2 evolutionary hypotheses as to why organisms age and die, mutation accumulation hypothesis. Deleterious mutations that affect later age classes accumulate in populations because selection against them is weak: antagonistic pleiotropy hypothesis. Where one gene causes two traits - one that is beneficial and one that is deleterious. Early reproduction contributes to more fitness: fecundity: positively correlated with body size! Early investment in growth, self-maintenance and self defense can lead to even greater fecundity later in life. Low survival rates (in high-predation sites) evolution of early reproduction! But most mutations are harmful to organisms: two alternate hypotheses to explain the evolution of existing mutation rates: Low frequency of mutations is favored by the evolution of slightly inefficient dna repair enzymes. Minimal mutation rate hypothesis: dna repair enzymes are as efficient as they can be, mutations are a net cost to organisms and are minimized, mutator alleles , asexual populations:
