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Evolution Vocab
summer assmnt vocab
22
Biology
11th Grade
09/14/2011

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Term
Homologous Structures
Definition
structures in different species that are similar because of common ancestry
Term
analogous structures
Definition
structures in different species that are similar because of convergent evolution rather than descent from a common ancestor with the same trait
Term
vestigial structures
Definition
features that apparently serve no function in an organism and are allegedly holdovers from an evolutionary past.
Term
Directional selection
Definition
natural selection that favors individuals at one end of the phenotypic range
Term
Diversifying/Disruptive selection
Definition
natural selection that favors individuals on both extremes of a phenotypic range over intermediate phenotypes
Term
stabilizing selection
Definition
Natural selection that favors intermediate variants by acting against extreme phenotypes
Term
Artificial selection
Definition
the selective breeding of domesticated plants and animals to encourage the occurence of desirable traits
Term
Phenotypic polymorphism
Definition
the existence of two or more distinct morphs each represented in a population in high enough frequencies to be readily noticeable
Term
Cline
Definition
a graded variation in a trait that parallels a gradient in the environment
Term
Outbreeding
Definition
Mating of genetically unrelated individuals
Term
heterozygote advantage
Definition
greater reproductive success of heterozygote individuals compared to homozygotes;tends to preserve variation in gene pools
Term
genetic drift
Definition
unpredictable fluctuations in allele frequencies from one generation to the next b/c of a populations finite size
Term
gene flow
Definition
genetic additions to or subtractions from a population resulting from the movement of fertile individuals or gametes
Term
Mutation
Definition
a change in the DNA of a gene, ultimately creating genetic diversity
Term
Bottleneck effect
Definition
Genetic drift resulting from the reduction of a population,such that the surviving population is no longer genetically representative of the original population
Term
Population
Definition
a localized group of individuals that belong to the same biological species (that are capable of interbreeding and producing fertile offspring)
Term
Reproductive Isolation
Definition
the existence if biological factors(barriers) that impede members of two species from producing viable, fertile hybrids.
Term
Allopatric speciation
Definition
a mode of speciation induced when an ancestral population becomes segregated by a geographical barrier or is itself divided into two geographically isolated subpopulations
Term
Sympatric Speciation
Definition
A mode of speciation occuring as a result of a radical change in the genome of a subpopulation, reproductively isolating the subpopulation from the parent population
Term
Mechanical Isolation
Definition
morphological differences like genitals and appearance that prevent successful mating
Term
Temporal Isolation
Definition
Species that breed during different times of the day, different seasons, or different years and cannot mix their gametes
Term
Adaptive radiation
Definition
the emergence of numerous species from a common ancestor introduced into an environment that presents a diversity of new oppurtunities and challenges
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