chapter 15 and 16 bio vocab
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20 terms
Terms | Definitions |
|---|---|
 adaptation | a trait that increases the ability of an individual to survive and reproduce compared to individuals without the trait |
| adaptive radiation | the rise of many new species in a relatively short time as a result of a single species that invades different habitats and evolves under different environmental pressures in those habitats |
| allele frequency | for any given gene, the relative proportion of each allele of that gene in a population |
| directional selection | a type of natural selection in which one extreme phenotype is favored over all others |
| disruptive selection | a type of natural selection in which both extreme phenotypes are favored over the average phenotype |
| founder effect | a type of genetic drift in which an isolated population founded by a small number of individuals may develop allele frequencies that are very different from those of the parent population as a result of chance inclusion of disproportionate numbers of certain alleles in the founders |
| sympatric speciation | speciation that occurs in populations that are not physically divided; normally due to ecological isolation or chromosomal aberrations |
| species | the basic unit of taxonomic classification |
| speciation | the process of species formation, in which a single species splits into two or more species |
| reproductive isolation | the failure of organisms of one population to breed successfully with members of another, may be due to premating or postmating isolating mechanisms |
| geographical isolation | the separation of two populations by a physical barrier |
| gene flow | the movement of alleles from one population to another owing to the migration of individual organisms |
| gene pool | the total of all alleles of all genes in a population; for a single gene, the total of all the alleles of that gene that occur in a population |
| genetic drift | a change in the allele frequencies of a small population purely by chance |
| hardy-weinberg principle | a mathematical model proposing that, under certain conditions, the allele frequencies and genotype frequencies in a sexually reproducing population will remain constant over generations |
| natural selection | the unequal survival and reproduction of organisms due to environmental forces (survival of the fittest) |
| allopatric speciation | speciation that occurs when two populations are separated by a physical barrier that prevents gene flow between them (geographical isolation) |
| ecological isolation | the lack of mating between organisms belonging to different populations that occupy distinct habitats within the same general area |
| gamete incompatibility | the inability of sperm from one species to fertilize eggs of another species |
| polyploidy | having more than two homologous chromosomes of each type |
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