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29 Cards in this Set

  • Front
  • Back
change in the genetic makeup of a population from genearation to generation
population genetics
the study of how populations change genetically over time
modern synthesis
a comprehensove theory of evolution that integrated ideas from many other fields
gene pool
the aggregate of genes in a population at any one time
Hardy-Weinberg Theorem
states that the frequencies of alleles and genotypes in a population's gene pool remain constant from generation to generation
changes in the nucleotide of DNA
Gene Duplication
important source of variation
Genetic Drift
alelle frequencies fluctuate unpredictable from one generation to another
Bottleneck effect
a sudden change in the enviornment may drastically reduce the size of a population
founder effect
when a few individuals become isolated from a larger population this smaller group may establish a new population whose gene pool is not reflective of the source population
gene flow
genetic addition to and/or subtractions from a population resulting from the movement of fertile individuals or gametes
phenotypic polymorphism
tow or more distinct morphs are each represented in high enough frequencies to be readily noticable
genetic polymorphisms
heritable morphisms
average heterozygosity
the average percent of these loci that are heterozygous
geographic variation
differences between the gene pools of seperate populations or population subgroups
the contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals
relative fitness
the contribution of a genotype to the next generation compared to the contribuitons of alternative genotypes for the same locus
directional selection
when a population's enviornment changes or when members of a population migrate to a new habitat with different enviornmental conditions than their former ones
disruptive selection
occurs when conditions favor individuals on both extremes of a phenotypic range over individuals with intermediate phenotypes
stabalizing selection
acts against extreme phenotypes and favors intermediate variants
balancing selection
occurs when natural selection maintains stable frequencies of two or more phenotypic forms in a population
heterzygote advantage
individuals have greater fitness
frequency- dependent
the fitness of any one morph declines if it becomes too common in the population
neutral variation
no selective advantage in the untranslated parts of the genome
genes that have become inactivated by mutations , genetic noise is free to accumulate in all parts of the gene
sexual selection
natural selection for mating success
sexual dimorphism
marked differences between the sexes in secondary sexual characteristics, which are not directly associated with reproduction
intrasexual selection
selection within the same sex, is a direct competition among individuals of one sex for mates of the opposite sex
intersexual selection
individuals of one sex are choosy in selecting their mates from the other sex