20 terms

chapter 15 and 16 bio vocab

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
the basic unit of taxonomic classification
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
having more than two homologous chromosomes of each type