BIOL 3863 Lecture Notes - Lecture 4: American Chestnut, Parallel Evolution, Dog Breeding
2 Sep 2016
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Evolution is not random: variation/mutation is though. Besides natural selection, there are 3 other ways that evolution takes place: artificial selection, humans pick and choose who survives and reproduce, ex. Dog breeding: genetic drift, chance events that affect/determine allele frequencies, more important to small poplulations, ex. Florida panthers: sexual selection (trade-off (discussed later in notes), selection for traits that improve reproductive success, but not necessarily survival. Sexual dimorphism: different phenotypes between sexes, ex. Snake size (in many species of snakes, the males and females differ in size) Reproductive barrier needed for speciation: physical barrier (ex. Mountains, ocean, etc : climate, genetic barrier (ex. Temporal (sexually active at different temperatures/times of year) Red crossbill: at least 10 types in north america, differ in breeding range, food (size of pinecones), and call. Results in structures that are analogous, but not homologous: ex. Bat wings vs bird wings: analogous similar in form/function, but not genetically related, homologous derived from same structure (ex.
