Chapter 22: Mechanisms of Evolution--KEY TERMS & DEFINITIONS

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University of Toronto Scarborough
Biological Sciences
Kamini Persaud

Key TermsChapter 22: The Mechanisms of Evolution 22.1-What facts form the base of our understanding of evolution? According to Darwin, the major features of evolutionary change are: o Species are not immutable, they change over time o The process that produces these changen saiural selection Variations among individuals affect the chance that a given individual will survive and reproduce. Darwin called this differential survival and reproduction of individualsnatural selection. Artificial selection: individuals with certain desirable traits by animal and plant breeders. Population: a group of individuals of a single species that live and interbreed in a particular geographic area at the same time. Adaptation: refers to the process by which characteristics appear to be useful to their bearers evolve (evolutionary mechanisms), and to the characteristics themselves. o An adaptation is a phenotypic characteristic that has helped an organism adjust to conditions in its environment. For a population to evolve, its members much possess heritable genetic variation, which is the raw material on which mechanisms of evolution act. Heritable trait: a characteristic of an organism that is at least partly determined by its genes. The genetic constitution that governs a characteristic is called a genotype. A population evolves when individuals with different genotypes survive or reproduce at different rates. Population genetics: o To explain the origin and maintenance of generic variation o To explain the patterns and organization of genetic variation o To understand the mechanism that cause changes in allele frequencies in populations Different forms of genes, calle adlleles, may exist at a particular locus.
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