BIOL 1202 Lecture Notes - Lecture 2: Convergent Evolution, Exponential Growth, Natural Selection
Document Summary
Dar(cid:449)in"s o(cid:271)ser(cid:448)ations and their inferen(cid:272)es: observation 1. Populations have potential for exponential growth: observation 2. Population size is normally stable: observation 3. Traits are variable among individuals of a population: observation 4. Most of those variable traits can be inherited. Survival is a struggle, and only a fraction will survive. Survival is not usually random, but is largely dependent upon heritable traits. Unequal survival of individuals will lead to gradual change in population. Natural selection is differential success in reproduction. Natural selection: (cid:862)nature(cid:863) pi(cid:272)ks the phe(cid:374)otypes that (cid:449)ill sur(cid:448)i(cid:448)e, the result of natural selection is the adaptation of organisms to their environment. This adaption is evolution: natural selection occurs from the interaction between the environment and the variability of the population. Natural selection is insured by an excess of offspring and variation in the population. Small changes accumulated each generation can result in major changes over evolutionary time.
