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| descent with modification; how a species' genotype and phenotype changes over time |
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| the remains or traces of organisms from the past |
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| layers of rock; layers of sediment which build up over time |
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| the principle that events in the past occurred suddenly and were caused by mechanisms different from those operating today |
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| the principle that mechansims of change are constant over time |
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| characteristics of organisms that enhance their survival and reproduction in specific environments |
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| a process in which individuals with certain inherited traits leave more offspring than individuals with other traits |
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| the process of modifying other species over many generations by selecting and breeding individuals that possess desired traits |
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| similarity resulting from common ancestry |
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| variations on a structural theme that was present in two species' common ancestor |
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| remnants of features that served important functions in the organisms' ancestors |
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| a diagram that reflects evolutionary relationships among groups of organisms |
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Definition
| the independent evolution of similar features in different lineages |
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| resemblance among species because of convergent evolution |
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| the geographic distribution of the species |
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| the slow movement of Earth's continent over time |
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| single massive continent that existed about 250 million years ago |
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| unique to a specific location |
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Definition
| change in allele frequencies in a population over generations |
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| the average percent of loci that are heterozygous |
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Definition
| differences in the genetic composition of separate populations |
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| a graded change in character along a geographic axis |
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| a change in the nucleotide sequence of an organism's DNA |
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| a group of individuals of the same species that live in the same area and interbreed, producing fertile offspring |
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Definition
| consists of all the alleles for all the loci in all individuals of the population |
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| states that the frequencies of alleles and genotypes in a population will remain constant from generation to generation, provided that only Mendelian segregation and recombination of alleles are at work |
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Term
| Hardy-Weinberg equilibrium |
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Definition
| the state of a gene pool which meets the Hardy-Weinberg principle |
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Definition
| a process in which chance events cause allele frequencies to fluctuate, especially in small populations |
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Definition
| when a few individuals become isolated from a larger population and establish a new population whose gene pool differs from the source of the population |
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| caused by a severe drop in population size; some alleles (by chance) can be overrepresented, underrepresented, or absent in the survivors |
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Definition
| the transfer of alleles into or out of a population due to the movement of fertile individuals or their gametes |
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| the contribution an individual makes to the gene pool of the next generation, relative to the contribution of other individuals |
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Definition
| occurs when conditions favor individuals exhibiting one extreme of phenotypic range; thereby shifting the frequency curve in one direction or the other |
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| occurs when conditions favor individuals at both extremes of a phenotypic range |
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Definition
| acts against both extreme phenotypes and favors intermediate variants |
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Definition
| a form of natural selection in which individuals with certain inherited characteristics are more likely than others to obtain mates |
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Definition
| marked differences between the two sexes secondary sexual characteristics |
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Definition
| selection within the same sex; individuals of one sex compete directly for mates of the other sex |
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Definition
| individuals of one sex are choosy in selecting their mates from the other sex (mate choice) |
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Definition
| occurs when natural selection maintains two or more forms in a population |
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Definition
| when individuals who are heterozygous at a particular locus have greater fitness than do both kinds of homozygotes |
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Term
| frequency-dependent selection |
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Definition
| the fitness of a phenotype declines if it becomes too common in the population |
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Term
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Definition
| nucleotide differences in noncoding sequences appear to confer no selective advantage or disadvantage |
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