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| The study of the past and present distribution of species |
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| The selective breeding of domesticated plants and animals to encourage the occurrence of desirable traits. |
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| The hypothesis by Georges Cuvier that each boundary between strata corresponded in time to a catastrophe, such as a flood or drought, that had destroyed many of the species living there at that time |
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| descent with modification |
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| Darwin’s initial phrase for the general process of evolution. |
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| All the changes that have transformed life on Earth from its earliest beginnings to the diversity that characterizes it today |
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| An accumulation of inherited characteristics that enhance organisms’ ability to survive and reproduce in specific environments |
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| A preserved remnant or impression of an organism that lived in the past |
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| A view of Earth’s history that attributes profound change to the cumulative product of slow but continuous processes. |
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| Structures in different species that are similar because of common ancestry |
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| Similarity in characteristics resulting from a shared ancestry |
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| Rock formed from sand and mud that once settled in layers on the bottom of seas, lakes, and marshes. Sedimentary rocks are often rich in fossils |
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| Charles Lyell’s idea that geologic processes have not changed throughout Earth’s history |
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| A structure of marginal, if any, importance to an organism. Vestigial organs are historical remnants of structures that had important functions in ancestors. |
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| The percent, on average, of a population’s loci that are heterozygous in members of the population. |
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Term
| balanced polymorphism/balancing selection |
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Definition
| The ability of natural selection to maintain diversity in a population. |
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Definition
| Genetic drift resulting from the reduction of a population, typically by a natural disaster, such that the surviving population is no longer genetically representative of the original population. |
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| A graded variation in a trait that parallels a gradient in the environment |
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| Natural selection that favors individuals at one end of the phenotypic range. |
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| Natural selection that favors individuals on both extremes of a phenotypic range over intermediate phenotypes |
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| The contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals. |
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| Genetic drift that occurs when a few individuals become isolated from a larger population, with the result that the new population’s gene pool is not reflective of the original population. |
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| frequency-dependent selection |
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Definition
| A decline in the reproductive success of a morph resulting from the morph’s phenotype becoming too common in a population; a cause of balanced polymorphism in populations. |
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| Genetic additions to or substractions from a population resulting from the movement of fertile individuals or gametes. |
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| Unpredictable fluctuations in allele frequencies from one generation to the next because of a population’s finite size. |
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Definition
| The existence of two or more distinct alleles at a given locus in a population’s gene pool. |
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| Hardy-Weinberg equilibrium |
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Definition
| The condition describing a non-evolving population (one that is in genetic equilibrium). |
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Definition
| The principle that frequencies of alleles and genotypes in a population remain constant from generation to generation, provided that only Mendelian segregation and recombination of alleles are at work. |
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| Selection whereby individuals of one sex (usually females) are choosy in selecting their mates from individuals of the other sex; also called mate choice. |
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Definition
| A direct competition among individuals of one sex (usually the males in vertebrates) for mates of the opposite sex. |
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| Evolutionary change below the species level; change in the genetic makeup of a population from generation to generation. |
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| A comprehensive theory of evolution emphasizing populations as units of evolution and integrating ideas from many fields, including genetics, statistics, paleontology, taxonomy, and biogeography. |
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| Genetic diversity that confers no apparent selective advantage. |
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| The existence of two or more distinct morphs (discrete forms), each represented in a population in high enough frequencies to be readily noticeable. |
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| The coexistence of two or more distinct forms in the same population. |
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| A localized group of individuals that belong to the same biological species (that are capable of interbreeding and producing fertile offspring). |
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Definition
| A DNA segment very similar to a real gene but which does not yield a functional product; a gene that has become inactivated in a particular species because of mutation. |
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| The contribution of one genotype to the next generation compared to that of alternative genotypes for the same locus. |
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Definition
| special case of polymorphism based on the distinction between the secondary sex characteristics of males and females. |
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| Natural selection that favors intermediate variants by acting against extreme phenotypes. |
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| The emergence of numerous species from a common ancestor introduced into an environment that presents a diversity of new opportunities and challenges. |
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| The variation in the relative rates of growth of various parts of the body, which helps shape the organism. |
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Definition
| A mode of speciation induced when an ancestral population becomes segregated by a geographic barrier or is itself divided into two or more geographically isolated subpopulations. |
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| common type of polyploid species resulting from two different species interbreeding and combining their chromosomes. |
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Definition
| An individual that has more than two chromosome sets, all derived from a single species |
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Term
| biological species concept |
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Definition
| Definition of a species as a population or group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring, but are not able to produce viable, fertile offspring with members of other populations. |
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| ecological species concept |
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Definition
| Defining species in terms of ecological roles (niches). |
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Definition
| Evolutionary change in the timing or rate of an organism’s development. |
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Definition
| Any of the genes that control the overall body plan of animals and plants by controlling the developmental fate of groups of cells. |
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Definition
| Evolutionary change above the species level, including the appearance of major evolutionary developments, such as flight, that we use to define higher taxa. |
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| morphological species concept |
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Definition
| Defining species by measurable anatomical criteria. |
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Definition
| The retention in an adult organism of the juvenile features of its evolutionary ancestors. |
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| paleontological species concept |
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Definition
| Definition of species based on morphological differences known only from the fossil record. |
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| phylogenetic species concept |
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Definition
| Defining a species as a set of organisms with a unique genetic history. |
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Definition
| A chromosomal alteration in which the organism possesses more than two complete chromosome sets. |
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| Any of several species-isolating mechanisms that prevent hybrids produced by two different species from developing into viable, fertile adults. |
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| A reproductive barrier that impedes mating between species or hinders fertilization of ova if interspecific mating is attempted. |
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| In evolutionary theory, long periods of apparent stasis (no change) interrupted by relatively brief periods of sudden change. |
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| The existence of biological factors (barriers) that impede members of two species from producing viable, fertile hybrids. |
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| The origin of new species in evolution |
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| A theory maintaining that species living the longest and generating the greatest number of species determine the direction of major evolutionary trends. |
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Definition
| A mode of speciation occurring as a result of a radical change in the genome of a subpopulation, reproductively isolating the subpopulation from the parent population. |
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