4.2.5: Key Terms
- Page ID
- 97105
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)- adaptive evolution
- increase in frequency of beneficial alleles and decrease in deleterious alleles due to selection
- allele frequency
- (also, gene frequency) rate at which a specific allele appears within a population
- assortative mating
- when individuals tend to mate with those who are phenotypically similar to themselves
- bottleneck effect
- magnification of genetic drift as a result of natural events or catastrophes
- cline
- gradual geographic variation across an ecological gradient
- directional selection
- selection that favors phenotypes at one end of the spectrum of existing variation
- diversifying selection
- selection that favors two or more distinct phenotypes
- evolutionary fitness
- (also, Darwinian fitness) individual’s ability to survive and reproduce
- founder effect
- event that initiates an allele frequency change in part of the population, which is not typical of the original population
- frequency-dependent selection
- selection that favors phenotypes that are either common (positive frequency-dependent selection) or rare (negative frequency-dependent selection)
- gene flow
- flow of alleles in and out of a population due to the individual or gamete migration
- gene pool
- all the alleles that the individuals in the population carry
- genetic drift
- effect of chance on a population’s gene pool
- genetic structure
- distribution of the different possible genotypes in a population
- genetic variance
- diversity of alleles and genotypes in a population
- geographical variation
- differences in the phenotypic variation between populations that are separated geographically
- good genes hypothesis
- theory of sexual selection that argues individuals develop impressive ornaments to show off their efficient metabolism or ability to fight disease
- handicap principle
- theory of sexual selection that argues only the fittest individuals can afford costly traits
- heritability
- fraction of population variation that can be attributed to its genetic variance
- honest signal
- trait that gives a truthful impression of an individual’s fitness
- inbreeding
- mating of closely related individuals
- inbreeding depression
- increase in abnormalities and disease in inbreeding populations
- macroevolution
- broader scale evolutionary changes that scientists see over paleontological time
- microevolution
- changes in a population’s genetic structure
- modern synthesis
- overarching evolutionary paradigm that took shape by the 1940s and scientists generally accept today
- nonrandom mating
- changes in a population’s gene pool due to mate choice or other forces that cause individuals to mate with certain phenotypes more than others
- population genetics
- study of how selective forces change the allele frequencies in a population over time
- population variation
- distribution of phenotypes in a population
- relative fitness
- individual’s ability to survive and reproduce relative to the rest of the population
- selective pressure
- environmental factor that causes one phenotype to be better than another
- sexual dimorphism
- phenotypic difference between a population's males and females
- stabilizing selection
- selection that favors average phenotypes