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Definition
| An RNA molecule that functions as an enzyme, catalyzing reactions during RNA splicing |
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| Evolutionary change above the species level, including the origin of a new group of organisms or a shift in the broad pattern of evolutionary change over a long period of time. Examples of macroevolutionary change include the appearance of major new features of organisms and the impact of mass extinctions on the diversity of life and its subsequent recovery |
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| Structures in different species that are similar because of common ancestry |
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| A process in which organisms with certain inherited characteristics are more likely to survive and reproduce than are organisms with other characteristics |
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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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| The slow movement of the continental plates across the Earth's surface |
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| An individual that has more than two chromosomes sets that are all derived from a single species |
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| A collection of abiotically produced molecules surrounded by a membrane or membrane-like structure |
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| Descent with modification; the idea that living species are descendants of ancestral species that were different from the present-day ones; also defined more narrowly as the change in the genetic composition of a population from generation to generation |
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| Period of evolutionary change in which groups of organisms form many new species whose adaptations allow them to fill vacant ecological roles in their communities |
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| The aggregate of all the alleles for all the loci in all individuals in a population; used in a more restricted sense as the aggregate of alleles for just one or few loci in a population |
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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 percent, on average, of a population's loci that are heterozygous in members in the population |
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| In the fossil record, long periods of apparent stasis, in which a species undergoes little or no morphological change, interrupted by relatively brief periods of sudden change |
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| The amount of time it takes for 50% of a sample of a radioactive isotope to decay |
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| Offspring that results from the mating of individuals from two different species or two true-breeding varieties of the same species |
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| A reproductive barrier that impedes mating between species or hinders fertilization if interspecific mating is attempted |
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| Genetic drift that occurs when the size of a population is reduced, as by a natural disaster or human actions; typically, the surviving population is no longer genetically representative of the original population |
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Definition
| The contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals in the population |
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| Greater reproductive success of heterozygous individuals compared with homozygotes; tends to preserve variation in a gene pool |
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| The principle stating that mechanisms of change are constant over time |
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| The principle stating that mechanisms of change are constant over time |
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| A branching diagram that reflects a hypothesis about evolutionary relationships among groups of organisms |
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| Frequency-dependent selection |
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Definition
| A decline in the reproductive success of individuals that have a phenotype that has become too common in a population |
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| Ecological species concept |
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| A definition of species in terms of ecological niche, the sum of how members of the species interact with the nonliving and living parts of their environment |
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| Hardy-Weinberg equilibrium |
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| The condition describing a nonevolving population (one that is in genetic equilibrium) |
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| An evolutionary process in which one species splits in two or more species |
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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 at work |
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| Marked differences between the secondary sex characteristics of males and females |
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| The selective breeding of domesticated plants and animals to encourage the occurrence of desirable traits |
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| Differences between the gene pools of geographically separate populations or population subgroups |
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| Phylogenetic species concept |
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| A definition of species as the smallest group of individuals that share a common ancestor, forming on branch on the tree of life |
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| A population or group of populations whose members have the potential to interbreed in nature and produce viable fertile offspring but do not produce viable fertile offspring with members of other groups |
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| A change in the nucleotide sequence of an organism's DNA ultimately creating genetic diverisity |
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| The principle that events in the past occurred suddenly were caused by different mechanisms than those operating today |
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| A relatively brief time in geologic history when large hard bodied forms of animals with most of the major body plans known today appeared in the fossil record |
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| Natural selection in which individuals at one end of the phenotypic range survive or reproduce more successfully than do other individuals |
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| A process in which chance events cause unpredictable fluctuations in allele frequencies from one generation to the next; effect of genetic drift are most pronounced in small populations |
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| The evolution of similar features in independent evolutionary lineages |
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| A hypothesis for the origin of eukaryotes consisting of a sequence of endosymbiotic events in which mitochondria, chloroplasts, and perhaps other cellular structures were derived from small prokaryotes that had been engulfed by larger cells |
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| The study of the past and present distribution of species |
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| Natural selection that maintains two or more phenotypic forms in a population |
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| The retention in an adult organism of the juvenile features of its evolutionary ancestors |
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| The formation of new species in populations that live in the same geographic area |
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| A geographic region in which members of different species meet and mate, producing a t least some offspring of mixed ancestry |
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| A localized group of individuals of the same species that can interbreed producing offspring |
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| Natural selection in which intermediate phenotypes survive or reproduce more successfully than do extreme phenotypes |
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Definition
| The supercontinent that formed near the end of the Paleozoic era when the plate movements brought all the landmasses of Earth together |
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| A structure of marginal, if any, importance to an organism; vestigial structures are historical remnants of structures that had important functions in ancestors |
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Definition
| A structure of marginal, if any, importance to an organism; vestigial structures are historical remnants of structures that had important functions in ancestors |
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| The division of Earth's history into time periods, grouped into three eons Archaean, Proterzoic, and Phanerozoic and further subdivided into eras, periods, and epochs |
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| A rock layer formed when new layers of sediment cover older ones and compress them |
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| A chromosomal alteration in which the organism possesses more than two complete chromosome sets; it is the result of an accident of cell division |
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| a graded change in a character along a geographic axis |
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| Referring to a species that is confined to a specific relatively small geographic area |
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| A reproductive barrier that prevent hybrid zygotes produced by two different species from developing into viable fertile adults |
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| Any of the master regulatory genes that control placement and spatial organization of body parts in animals, plants, and fungi by controlling the developmental fate of groups of cells |
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| Layered rock that results from the activities of prokaryotes that bind thin films of sediment together |
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| A fertile individual that has more than two chromosome sets as a result of two different species interbreeding and combining their chromosomes |
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| Having characteristics that are similar because of convergent evolution not homology |
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| The existence of biological factors (barriers) that impede members of two species from producing viable fertile offspring |
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| The scientific study of fossils |
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Definition
| Genetic drift that occurs when a few individuals become isolated from a larger population and form a new population whose gene pool composition is not reflective of that of the original population |
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Definition
| Period of time when global environmental changes lead to the elimination of large number species throughout Earth |
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| Morphological species concept |
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| A definition of species in terms of measurable anatomical criteria |
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Definition
| Evolutionary change below the species level; change in the allele frequencies in a population over generations |
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| A method for determining the absolute ages of rocks and fossils based on the half-life of radioactive isotopes |
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Definition
| A process in which natural selection strengthens prezygotic barriers to reproduction thus reducing the chances of hybrid formation; such process is likely to occur only if hybrid offspring are less fit than members of the parent species |
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Definition
| Natural selection in which individuals on both extremes of a phenotypic range survive or reproduce more successfully than do individuals with intermediate phenotypes |
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Definition
| A process in which a unicellular organism (the host) engulfs another cell, which lives within the host cell and ultimately becomes an organelle in the host cell; also refers to the hypothesis that mitochondria and plastids were formerly small prokaryotes that began living within larger cells |
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Definition
| Genetic variation that does not appear to provide a selective advantage or disadvantage |
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Definition
| A preserved remnant or impression of an organism that lived in the past |
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Definition
| A form of natural selection in which individuals with certain inherited characteristics are more likely than other individuals to obtain mates |
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Definition
| Similarity in characteristics resulting from a shared ancestry |
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Definition
| Inherited characteristic of an organism that enchances its survival and reproduction in specific environments |
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Definition
| Evolutionary change in the timing or rate of an organism's development |
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Definition
| 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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Definition
| The transfer of alleles from one population to another, resulting from the movement of fertile individuals or their gametes |
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Definition
| The formation of new species in populations that are geographically isolated from one another |
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