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20 Cards in this Set
- Front
- Back
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____is the primary mechanism of adaptive evolution
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natural selection
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accumulates and maintains favorable genotypes in a population
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natural selection
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natural selection increases the frequencies of ____, fitting organisms to their environment over generations
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certain (favorable) genotypes
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population geneticists measure genetic variation both at the level of __1__and at the __2__
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1) whole genes
2) molecular level of DNA |
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what is genetic diversity?
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the average percent of gene loci that are heterozygous
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human genetic variation?
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1) gene diversity = 14%
2) nucleotide diversity= 0.1% (you and your neighbor have the same nucleotide at 999 out of every 1000 nucleotide sites in your DNA |
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What is directional selection?
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shift in allele frequencies in a consistent direction
(phenotypic variation in a population of butterflies) |
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What are examples of directional selection?
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1) peppered moths
2) pesticide resistance 3) antibiotic resistance |
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with directional selection, allele frequencies tend to shift in response to...
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directional changes in the environment
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what is stabilizing selection?
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intermediate forms are favored and extremes are eliminated
-alleles that specify extreme forms are eliminated from a population |
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what is disruptive selection?
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both forms at the extreme ends are favored; intermediate forms are eliminated
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what are the 3 types of selection?
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1) directional selection
2) stabilizing selection 3) disruptive selection |
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Individuals of a population...
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have the same number and kind of genes
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a populations is evolving when..
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a trait is becoming more or less common
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genetic equilibrium is used as..
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a baseline for measuring changes
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___are the only source of new alleles
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gene mutations
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natural selection is an outcome of...
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differences in survival and reproduction among individuals
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___may drift the range of variation for a trait
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selection pressure
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___is a change in allele frequencies
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gene flow
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___is a change in allele frequencies over the generations due to chance events
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genetic drift
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