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| Structures in different species that are similar because of common ancestry |
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| Differential success in the reproduction of different phenotypes resulting from the interaction of organisms with their environment. Evolution occurs when natural selection causes changes in relative frequencies of alleles in the gene pool. |
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| An accumulation of inherited characteristics that enhance organisms’ ability to survive and reproduce in specific environments. |
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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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| Ordered division of organisms into categories based on a set of characteristics used to assess similarities and differences, leading to a classification scheme; the branch of biology concerned with naming and classifying the diverse forms of life. |
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| A preserved remnant or impression of an organism that lived in the past. |
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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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| The scientific study of fossils. |
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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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| A view of Earth’s history that attributes profound change to the cumulative product of slow but continuous processes. |
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| Charles Lyell’s idea that geologic processes have not changed throughout Earth’s history. |
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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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| The selective breeding of domesticated plants and animals to encourage the occurrence of desirable traits. |
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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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| Similarity in characteristics resulting from a shared ancestry. |
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| The study of the past and present distribution of species. |
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| Referring to a species that is confined to a specific, relatively small geographic area. |
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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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| The study of how populations change genetically over time. |
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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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| 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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| The total aggregate of genes in a population at any one time. |
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| 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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| 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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| A change in the DNA of a gene, ultimately creating genetic diversity. |
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| An aberration in chromosome structure due to fusion with a fragment from a homologous chromosome, such that a portion of a chromosome is duplicated. |
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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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| 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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| 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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| Genetic additions to or substractions from a population resulting from the movement of fertile individuals or gametes. |
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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 percent, on average, of a population’s loci that are heterozygous in members of the population. |
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| Differences between the gene pools of separate populations or population subgroups. |
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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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| The contribution of one genotype to the next generation compared to that of alternative genotypes for the same locus. |
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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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| Natural selection that favors intermediate variants by acting against extreme phenotypes. |
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| Natural selection that maintains stable frequencies of two or more phenotypic forms in a population (balanced polymorphism). |
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| The ability of natural selection to maintain diversity in a population. |
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| Greater reproductive success of heterozygous individuals compared to homozygotes; tends to preserve variation in gene pools. |
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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 diversity that confers no apparent selective advantage. |
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| 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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| Natural selection for mating success. |
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| A special case of polymorphism based on the distinction between the secondary sex characteristics of males and females. |
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| A direct competition among individuals of one sex (usually the males in vertebrates) for mates of the opposite sex. |
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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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| The origin of new species in evolution. |
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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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| 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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| A group whose members possess similar anatomical characteristics and have the ability to interbreed. |
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| biological species concept |
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| 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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| The existence of biological factors (barriers) that impede members of two species from producing viable, fertile hybrids. |
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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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| Any of several species-isolating mechanisms that prevent hybrids produced by two different species from developing into viable, fertile adults. |
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| morphological species concept |
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| Defining species by measurable anatomical criteria. |
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| paleontological species concept |
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| Definition of species based on morphological differences known only from the fossil record. |
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| ecological species concept |
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| defining spoecies in terms of ecological roles (niches) |
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| phylogenetic species concept |
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| Defining a species as a set of organisms with a unique genetic history. |
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| 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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| 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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| A chromosomal alteration in which the organism possesses more than two complete chromosome sets. |
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| An individual that has more than two chromosome sets, all derived from a single species. |
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| A common type of polyploid species resulting from two different species interbreeding and combining their chromosomes. |
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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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| In evolutionary theory, long periods of apparent stasis (no change) interrupted by relatively brief periods of sudden change. |
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| Evolutionary change in the timing or rate of an organism’s development. |
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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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| The retention in an adult organism of the juvenile features of its evolutionary ancestors. |
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| 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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| 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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