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39 Cards in this Set
- Front
- Back
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Darwin's Key Claims |
-Common Ancestry -Population-level evolution -Natural Selection |
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Jean Baptiste Lamarck |
-Argued against Darwin and thought that species arose separately and progressed up the same ladder of advancement: WRONG |
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Darwins: change at population level |
- thought that the evolution must happen over a whole populatino |
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Speciation |
-lineage splitting involves the cessation of gene flow -this allows for descendants of lineages to evolve independently |
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Evidence for common ancestry |
- geographic distributions -fossil record -unexpected similarities among living species -patterns of variation among living and extinct organisms |
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Definition of evolution at the population level |
evolution is change over generations and the frequency of alleles in a population |
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Relationship between evolution and variation |
evolution gets rid of variation (if it's not balancing selection) |
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What might cause evolution? |
-genetic drift -selection |
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Genetic drift |
-fluctuation in allele frequencies by chance -always happening regardless of selection |
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directional selection |
- occurs when conditions favor individuals exhibiting one extreme of a phenotype range |
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disruptive selection |
occurs when conditions favor individuals at both extremes of a phenotypic range |
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stabilizing selection |
acts against both extreme phenotype and favors intermediate variants (phenotype) |
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balancing selection |
-heterozygote advantage and frequency dependent selection (genotype) |
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frequency dependent selection |
fitness of phenotype depends on how common it is in a population |
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In a smaller population with genetic drift it goes to fixation ___ |
faster the smaller the population the greater the impact of chance |
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Effect of genetic drift on variation? |
removes variation |
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Relative Fitness definition |
- the average reproductive output of individuals with a certain genotype -depends on the environment |
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Balancing selection and the relationship to evolution |
tends to inhibit evolution |
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Hardy Weinberg assumptions |
- random mating - no selection (all genotypes are same fitness) |
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Sexual selection |
-selected for improved mating success (even at the expense of survival) |
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runaway sexual selection |
- positive feedback loop of sexual selection - for example: females will favor males with long tails which will give their sons long tails so females will favor them |
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Group selection |
traits that improve the success of a multi-individual group may be favored even if they are disadvantageous within a group |
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Sympathetic speciation |
- speciation without geographic separation - could be due to a mutation or food sources |
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allopatric speciation |
- speciation from splitting geographic |
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GULOP gene |
detectable in humans but non-function -makes vitamin C |
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primate evolutionary traits |
-binocular vision, grasping hands, fingernails -free upper lip; vitamin C dependence -trichromatic vision -fewer premolars |
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Trichromatic vision |
- a light receptor gene on the X chromosome duplicated and the two copies became specialized for red vs green light -evolved from a gene duplication of the MW/LW opsin |
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when did bipedalism evolve? why? |
3 Ma - carrying stuff -better cooling -more efficient locomotion |
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Reproductive system of monotremes |
eggs (hatch early) - young nurse (milk but no nipple) |
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reproductive system of marsupials |
live birth but no placenta - young crawl to pouch (scrotum homolog) to nurse |
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reproductive system of placentals (Eutheria) |
- live birth with fully developed placenta |
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cambrian explosion was allowed for by |
increased oxygen levels |
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coloniality |
cells divide and stick together |
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how does coloniality provide a stepping stone? |
sister cells sticking together can be beneficial to all the cells |
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endosymbiotic origin -mitochondria |
- descended from an alpha-proteobacterium |
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inside out model |
mitochondria aquired before phagocytosis |
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Last Universal Common Ancestor (LUCA) traits |
-chemoautotropic (used chemical energy to fix carbon) -hyperthermophilic (lived in a very hot environment) -prokaryotic |
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when did life evolve? |
3.7 Ga |
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The surface metabolism theory |
life like chemistry arose spontaneously as "slimes" on mineral surfaces -cells evolved later -don't need membrane bound cells |
