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15 Cards in this Set

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fitness
# of offspring produced by an individual that survive to reproduce
relative fitness
# of offspring surviving to reproduce in comparison to other individuals in the population
adaptation
a trait that confers increased relative fitness on organisms that possess that trait
directional selection
occurs when natural selection favors phenotypes at one end of the distribution
stabilizing selection
occurs when natural selection favors phenotypes in the center of the distribution
disruptive/diversifying selection
occurs shen natural selection favors phenotypes at both extremes of the distribution; the mean phenotype has the lowest fitness
sexual selection
one sex, for Ex. females, can act as an agent of selection for the morphology of the other sex (not discussed in lecture)
speciation
species arise from subdivion of a lineage
lineage
a group of organisms that are related by descent from a common ancestor
biological species concept
a species is a group of naturally or potentially interbreeding population that are reproductively isolated from other such groups
phylogenetic species concept
an irreducible (basal) cluster of organisms, diagnosably distinct from other clusters, and within which there is a parental pattern of ancestry and descent. (Notice that this def. emphasizes the criterion of common descent. An advantage of this def. over the biological species concept is that it includes both asexually and sexually reproducing animals).
population
a unit of a species containing those organisms that are actually interbreeding
statis
NO CHANGE in a lineage over time
anagenesis
a lineage changes over time (e.g. due to natural selection of genetic drift), but these changes do not lead to a splitting of the lineage
extinction
a lineage ends; has no living descendents