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AP Bio Chapter 20/21

AP Bio Chapter 20/21: Phylogeny & Evolution of Populations

Phylogeny The evolutionary history of a species or group of related species.
Phylogenetic tree A branching diagram that represents a hypothesis about the evolutionary history of a group of organisms.
Shared derived characters An evolutionary novelty that is unique to a particular clade (represented by a speciation event that occurs at a node).
Maximum parsimony A principle that states that when considering multiple explanations for an observation, one should first investigate the simplest explanation that is consistent with the facts.
horizontal gene transfer The transfer of genes from one genome to another through mechanisms such as transposable elements
population A group of individuals of the same species that live in the same area and interbreed
Hardy-Weinberg equilibrium The state of a population in which frequencies of alleles and genotypes remain constant from generation to generation
genetic drift A process in which chance events cause unpredictable fluctuations in allele frequencies from one generation to the next. Effects of genetic drift are most pronounced in small populations.
founder effect Genetic drift that occurs when a few individuals become isolated from a larger population and form a new population whose gene pool composition is not reflection of that of the original population.
bottleneck effect Genetic drift that occurs when the size of a population is reduced
gene flow The transfer of alleles from one population to another
relative fitness The contribution an individual makes to the gene pool of the next generation
sexual selection A process in which individuals with certain inherited characteristics are more likely than other individuals of the same sex to obtain mates.
Directional Selection Natural selection in which individuals at one end of the phenotypic range survive or reproduce more successfully than do other individuals.
Disruptive selection Natural selection in which individuals on both extremes of a phenotypic range survive or reproduce more successfully than do individuals with intermediate phenotypes.
Stabilizing Selection Natural selection in which intermediate phenotypes survive or reproduce more successfully than do extreme phenotypes.
Created by: Hajra Maqsoos