Key Terms – Evolution
- adaptation
- a heritable trait or behavior in an organism that aids in its survival in its present environment
- adaptive radiation
- a speciation when one species radiates out to form several other species because of distinct niches or isolated habitats
- allele
- alternate forms of the same gene arising from mutations
- allopatric speciation
- a speciation that occurs via a geographic separation; “other homelands”
- analogous structure
- a structure that is similar because of evolution in response to similar selection pressures resulting in convergent evolution, not similar because of descent from a common ancestor
- bottleneck effect
- the magnification of genetic drift as a result of natural events or catastrophes
- convergent evolution; convergence
- an evolution that results in similar forms on different species
- dispersal
- an allopatric speciation that occurs when a few members of a species move to a new geographical area
- divergent evolution; divergence
- an evolution that results in different forms in two species with a common ancestor
- founder effect
- a magnification of genetic drift in a small population that migrates away from a large parent population (founder species) carrying with it an unrepresentative set of alleles
- gene flow
- the flow of alleles in and out of a population due to the migration of individuals or gametes
- gene pool
- all of the alleles carried by all of the individuals in the population
- genetic drift
- the effect of chance on a population’s gene pool
- genotype
- the genetic constitution of an individual organism
- homologous structure
- a structure that is similar because of descent from a common ancestor
- infertile
- unable to reproduce
- inheritance of acquired characteristics
- a phrase that describes the mechanism of evolution proposed by Lamarck in which traits acquired by individuals through use or disuse could be passed on to their offspring thus leading to evolutionary change in the population
- locus; loci
- physical location of a gene on a chromosome
- macroevolution
- a broader scale of evolutionary changes seen over paleontological time
- microevolution
- the changes in a population’s genetic structure (i.e., allele frequency)
- migration
- the movement of individuals of a population to a new location; in population genetics it refers to the movement of individuals and their alleles from one population to another, potentially changing allele frequencies in both the old and the new population
- modern synthesis
- the overarching evolutionary paradigm that took shape by the 1940s and is generally accepted today
- natural selection
- the greater relative survival and reproduction of individuals in a population that have favorable heritable traits, leading to evolutionary change
- non-viable
- not capable of living, growing, or developing and functioning successfully
- population genetics
- the study of how selective forces change the allele frequencies in a population over time
- phenotype
- the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment
- post-zygotic barriers
- reduces the viability or fertility of hybrids or their progeny
- pre-zygotic barriers
- mechanisms that prevent the fertilization of eggs
- reproductive isolation
- the inability of a species to breed successfully with related species due to geographical, behavioral, physiological, or genetic barriers or differences
- speciation
- a formation of a new species
- sympatric speciation
- a speciation that occurs in the same geographic space; “same homeland”
- variation
- the variety of alleles in a population
- vestigial structure
- a physical structure present in an organism but that has no apparent function and appears to be from a functional structure in a distant ancestor
- vicariance
- an allopatric speciation that occurs when something in the environment separates organisms of the same species into separate groups