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15 Cards in this Set
- Front
- Back
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Population/ gene pool
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population=individuals of same species in same area
gene pool=all the alleles in a population |
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allele frequencies
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Calculation of allele frequencies
-risk of heritable disease -important for study of evolution |
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Microevolution
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=allele frequency changes in a population
-nonrandom mating -migration -mutation -genetic drift (small pop.size) -natural selection |
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Hardy-Weinberg Equation
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to predict allele and genotype frequencies in a population
freq of dominant allele (A)=p freq of recessive allele (a)=q p+q=1 freq of homozy.dominant (AA)=p^2 freq of heteroz (Aa)=2pq freq of homozy recessive (aa)=q^2 p^2 + 2pq + q^2= 1 |
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Migration
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=gene flow between 2 previously isolated populations
rapidly changes allelic frequencies |
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Mutations
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create new alleles
most have harmful effects occasionally increase biological fitness |
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Natural Selection
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Resource limitations: prevent exponential pop.growth; lead to competition
Differential reproductive rates (due to heritable variation) Those w/ "advantageous" traits survive and reproduce |
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Heterozygotes Advantage
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maintains recessive deleterious alleles in population
ex.Malaria/sickel cell, PKU/fungal infection, cystic fibrosis/diarrheal diseases, diabetes/famine |
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Genetic Drift
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changes in allele frequencies due to chance.
ex. Founder effect (amish of lancaster) Population bottleneck |
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Human evolution
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Hominoids= 22-32 mya (ancestral to humans and apes)
Hominids= 4 mya (ancestral to humans only) Homo Habilis= 2.3 mya (first hominid to make/use stone tools) Homo Erectus= 2 mya to 400,000 ya (tools-hand axes, fire; separated from africa to asia) Homo Sapiens= 130,000 ya |
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Molecular Evolution
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fewer differences b/w a gene or protein sequence in 2 species the more closely related the species are presumed to be
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Important differences
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Hairiness: nonsense mutation in keratin gene
Fetal hemoglobin: lengthens fetal pd. and maximizes brain growth |
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comparing Protein sequences
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Cytochrome c (cellular resiration)..human and chimp cyt c is identical; human and pigeon differe by 12 aa
HOX genes (control order in which genes get turned on during devt) similar # and function in closely related species |
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Molecular clocks
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estimate time elapsed since 2 species diverged from same ancestor (based on DNA or protein sequence)
Parsimony analysis: simple, method w/ fewest steps is most likely. |
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Mitochondrial Eve
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Replacement hypothesis: all humans evolved from single lineage in Africa (most accepted)
Multiregional hypothesis: human traits originated in several places |
