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Bio Ch. 12

Mechanisms of Evolution

TermDefinition
MRSA methicillin-resistant S. aureus
VRSA vancomycin-resistant S. aureus
alleles different version of the same gene (sequences of DNA)
allele frequencies the proportions of specific alleles in a population
4 mechanisms of evolution natural selection, mutation, gene flow, & genetic drift
natural selection individuals with particular inherited characteristics survive & reproduce at a higher rate than other individuals in a population
3 common patterns of natural selection directional selection, stabilizing selection, & disruptive selection
directional selection individuals at one extreme of an inherited phenotypic trait have an advantage over other individuals in the population
stabilizing selection individuals with intermediate values of an inherited phenotypic trait have an advantage over other individuals in the population
disruptive selection individuals with either extreme of an inherited trait have an advantage over individuals with an intermediate phenotype
convergent evolution when distantly related organisms evolve similar structures because they survive & reproduce under similar environmental pressures
analogous traits the characteristics that result from convergent evolution
mutation a change in the sequence of any segment of DNA
horizontal gene transfer the process by which bacteria pass genes to one another, happens between the same generation
conjugation the process whereby bacteria send small, circular pieces of DNA called plasmids to each other through small tubes
gene flow the exchange of alleles between populations, and results in the change of allele frequencies in a population
genetic drift a change in allele frequencies caused by random differences in survival & reproduction among individuals in a population
2 main types of genetic drift genetic bottleneck & founder effect
genetic bottleneck a drop in the size of a population, for at least one generation, that causes a loss of genetic variation
founder effect occurs when a small group of individuals establishes a new population isolated from its original, larger population
sexual selection natural selection in which a trait increases an individual's chance of mating even if it decreases the individual's chance of survival
sexual dimorphism a distinct difference in appearance between the males and females of a species
what is the only way that new alleles are generated in a species mutation
Created by: nat.riv
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