The final exam of the semester looms in the distance, so PLEASE study! You have all of your notes/handouts. Here are a few categories to study:
Chapter 13:
1) Evidence for evolution: fossil record, biogeography, comparative anatomy (including homologous structures and vestigial structures), comparing embryonic development, and molecular biology (similarities in amino acid and DNA sequences)
2) Sources of genetic variation: mutation, crossing over and independent assortment (during meiosis), random fertilization
3) How do you know if a population is evolving? Hardy-Weinberg--that's how. Look over the equation, remembering what each variable represents!
4) The five conditions that must be met in order for a population to be in Hardy-Weinberg equilibrium (i.e. NOT evolving; stable allele frequencies): see p. 267
5) Things that alter allele frequencies in a population (i.e. lead to microevolution and disrupt HW equilibrium): a) genetic drift: changes that are due to chance alone (ex. bottlenecks and founder effect)
b) gene flow (alleles come in/leave a population); c) mutations (to a SMALL extent); and d) natural selection (the only mechanism that consistently leads to adaptive evolution) and there are three types: stabilizing, disruptive, directional. Sexual selection leads to differences in appearance (phenotype) between males and females of a species (think birds).
Chapter 14:
1) Definitions of species: biological, morphological, ecological, and phylogenetic (see p. 279)
2) Speciation: the formation of new species
3) Reproduction barriers keep species separate: prezygotic (there are 5); and postzygotic (there are 3)--see p. 281 Table 14.3
4) Types of speciation: a) allopatric (different environments/geographic isolation occurred); and b) sympatric: same environment; gene flow just stops or is drastically reduced (think polyploidy in plants, habitat differentiation, and sexual selection)
5) Hybrid zones: regions where members of diff. species meet and mate, producing at least some hybrid offspring. Outcomes could be: a) reinforcement; b) fusion; or c) stability
6) Adaptive radiation (concept discussed again in chapter 15): many diverse species arise from a common ancestor; is very common after a mass extinction because niches open up
7) Speciation can occur slowly (gradualism model) or rapidly (punctuated equilibrium model); fossil record supports the punctuated model
Chapter 15: I hope it is still pretty fresh on your minds.
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ReplyDeleteCan you explain the last half of ch. 15 (section 10-19). Also, can I take the final exam next week because I won't be able of to take the final Friday because of the flu?
ReplyDeleteYes, you may take the final Monday. Stay home and get well.:)
ReplyDeleteThe second half of chapter 15 is basically classification based on evolutionary relationships, i.e. phylogeny/systematics. Phylogenetic trees are based on shared derived characteristics. DNA sequences are also analyzed to determine relatedness between organsims. For example--humans and dogs would be more closely related than humans and lizards. Lizards are reptiles and would have less molecular (DNA) similarities with a human than would a dog and a human. Dogs and humans are both mammals and share a more recent ancestor. The farther apart two organisms are on a phylogenetic tree, the longer they have been diverging (becoming more different). If you look at the phylogenetic tree on p. 310, it is constructed using cladistics. The mammals are the 'ingroup'--the group being analyzed, and the iguana (reptile) is the 'outgroup' because it is the least related to the other and has been diverging from the 'ingroup' longer. The derived characteristics are noted by the yellow dots. These characteristics are used to put another group 'out' as you go down the tree until you are left with the group you are analyzing--the 'ingroup'.
Wow. I know I have rambled a bit here, but I hope it makes better sense now. Go back and read sections 15.16 and 15.17 and they should be a little easier to understand. And always look at the diagrams.