Ch1, 23 LIFE
Terms
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- Darwin
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1) species change over time
2) natural selection causes the changes - adaptation
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1) process by which adaptive traits are aqcquired by evolutionary mechanisms
2) traits that enhance the survival & reproductive success of their bearers - population genetics
- -apply Mendel's laws to populations of orgs
- gene pool
- the sum of all alleles in a population
- autotrophs ; heterotrophs
- -self-feeders ; other-feeders
- genus
- group w/ a recent common ancestor
- species
- - a specific type; no natural interbreeding
- systematics
- the scientific study of the diversity of organisms
- taxonomy
- under systematics, classifying organisms
- Phylogeny
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- a hypothesis that describes the history of descent from a common ancestor of a group of organisms
- phylogenetic tree – each node / split = speciation event - homologous
- features shared by 2 + species from a common ancestor
- derived trait
- a trait that differs from its ancestral form
- convergent evolution
- traits that were independently evolved become superficially similar b/c of similar selective pressures
- evolutionary reversal
- reverting back to ancestor state from derived state
- homoplastic traits / homoplasies
- traits that are similar not b/c of inheritance from common ancestor
- ancestral traits vs derived traits
- only traits in ingroup are derived; ancestral traits in ingroups and outgroups
- Evolutionary Agents causing HWE deviation
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1) Mutations
2) Migration
3) Genetic Drift
4) Nonrandom Mating
5) Natural Selection - mutations
- -are rare for each loci, but so many loci that there may be a few mutations in each zygote
- migration
- produces gene flow
- genetic drift
- the random loss of indivs and the alleles they possess
- population bottlenecks
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occasional periods a normally large pop. may go thru when only a small # of indivs. survive
-may increase/decrease an allele freq lots by chance being a bigger factor - founder effect
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a few indivs colonize region;
resulting change in genetic variation - nonrandom mating
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-like x like or like x unlike
-ie 2 flowers - pin (long stigma, short stamen/anther), thrum (short stigma, long stamen/anther) - natural selection
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when some indivs contribute more offspring to the next generation than others, changing allele freqs
-fitness - contribution of one relative to the phenotype of another - natural selection, quantified 3 ways
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1) stabilizing selection - avg. favored
2) directional selection - R or L
3) distruptive selection - both extremes - stabilizing selection
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-favors average indivs
-reduces variation - direction selection
- -indivs of one extreme are favored
- disruptive selection
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indivs at both extremes favored
-results in bimodal distribution
-ie bill sizes in black-bellied seedcracker of W. Africa