ANTHR 101 Lecture Notes - Lecture 5: Insect Wing, Melanism, Genetic Drift
Document Summary
Ex: industrial melanism moss that is colored to camouflage itself on trees to prevent being preyed on by birds. If none of the forces of evolution are at work, there will be no change in the genetic composition of the population over time. (no evolution!) Natural selection, mutation, genetic drift, non-random mating and gene flow all contribute to evolution. Time on x scale left to right. Extant species on top, extinct species on bottom. Definition: actually or potentially interbreeding natural populations that are reproductively isolated from other such groups. Reproductive isolating mechanisms: pre-mating isolation mechanisms recognizing that potential mates are not within their own species, post-mating isolation mechanisms when species could mate, and do, but their offspring are sterile and cannot reproduce themselves. Why: pre-mating isolation, it saves a lot of effort. Speciation: two processes: one is that the species as a whole evolves, adapts or mutates.
