Ap Bio-Evolution

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Artificial selection

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The selective breeding of domesticated plants and animals to encourage the occurrence of desirable traits.

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Biogeography

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The study of the past and present distribution of species.

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Catastrophism

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The hypothesis by Georges Cuvier that each boundary line 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 phase for the general process of evolution.

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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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Evolutionary adaptation

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An accumulation of inherited characteristics that enhance an organism's ability to survive and reproduce in specific environments.

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Fossil

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A preserved remnant or impression of an organism that lived in the past.

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Gradualism

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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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Homologous Structures

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Structures in different species that are similar due to common ancestry.

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Homology

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Similarity in different species resulting from a shared ancestry.

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Natural selection

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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 the gene pool.

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Palentology

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The scientific study of fossils.

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Sedimentary rock

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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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Taxonomy

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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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Uniformatarianism

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Charles Lyell's idea that geologic processes have not changed throughout earth's history.

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Vestigial organ

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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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Average heterozygosity

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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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Balanced polymorphism

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The ability of natural selection to maintain diversity in a population.

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Balancing selection

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Natural selection that maintains stable frequencies of two or more phenotypic forms in a population.

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Bottleneck effect

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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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Cline

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A graded variation in a trait that parallels a gradient in the environment.

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Directional selection

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Natural selection that favors individuals at one end of the phenotypic range.

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Disruptive selection

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Natural selection that favors individuals on both extremes of a phenotypic range over intermediate phenotypes.

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Fitness

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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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Founder effect

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Genetic drift that occurs when a few individuals get 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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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

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Gene flow

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Genetic additions to or subtractions from a population resulting from the movement of fertile individuals or gametes.

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Gene pool

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The total aggregate of genes in a population at any one time.

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Genetic drift

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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 polymorphism

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The existence of two or more distinct alleles at a given locus in a populations gene pool.

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Geographic variation

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Differences between the gene pools of separate populations or population subgroups.

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Hardy-Weinberg equilibrium

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The condition describing a non-evolving population (one that is in genetic equilibrium)

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Hardy-Weinberg theorem

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The principle that frequencies of alleles and genotypes in a population remain constant , provided that only Mendelian segregation and recombination of alleles are at work.

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Heterozygote advantage

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Greater reproductive success of heterozygotes compared to homozygotes; tends to preserve variation in gene pools

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Intersexual selection

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Selection whereby individuals of one sex (mainly females) are choosy in selecting their mates from individuals of the other sex; also called mate choice.

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Intrasexual selection

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A direct competition among individuals of one sex (usually the males in vertabraes) for mates of the opposite sex.

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Microevolution

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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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Modern synthesis

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A comprehensive theory of evolution emphasizing populations as units of evolution and integrating ideas from many fields, including genetics, paleontology, taxonomy, and biogeography.

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Mutation

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A change in the DNA of a gene, ultimately creating genetic diversity.

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Neutral variation

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Genetic diversity that confers no apparent selective advantage

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Phenotypic polymorphism

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The existence of 2 or more different morphs (discrete forms), each represented in a population in high enough frequencies to be readily noticeable.

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Polymorphism

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The coexistence of 2 or more distinct forms in the same population.

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Population

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A localized group of individuals that belong to the same biological species (capable of interbreeding and producing fertile offspring).

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Population genetics

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The study of how populations change genetically over time.

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Pseudogene

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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 species due to mutation.

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Relative fitness

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The contribution of one genotype to the next generation compared to that of alternative genotypes of the same locus.

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Sexual dimorphism

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A special case of polymorphism based on the distinction of secondary sex characteristics of males and females.

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Stabilizing selection

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Natural selection that favors intermediate variants by acting against extreme phenotypes.

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Adaptive radiation

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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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Allometric growth

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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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Allopatric speciation

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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 populations.

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Allopolyploid

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A common type of polyploid species resulting from two different species interbreeding and combining their chromosomes.

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Autopolyploid

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An individual that has more than two chromosome sets, all derived from a single species.

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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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Ecological species concept

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Defining species in terms of ecological roles (niches).

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Heterochrony

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Evolutionary change in the timing or rate on an organism's development.

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Homeotic gene

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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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Macroevolution

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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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Morphological species concept

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Defining species by measurable anatomical criteria.

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Paedomorphosis

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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 of species based on morphological differences only known form the fossil record.

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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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Polyploidy

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A chromosomal alteration in which the organism possesses more than two complete chromosome sets.

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Postzygotic barrier

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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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Prezygotic barrier

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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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Punctuated equilibrium

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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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Reproductive isolation

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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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Speciation

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The origin of new species in evolution.

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Species

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A group whose members possess similar anatomical characteristics and have the ability to interbreed

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Species selection

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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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Sympatric speciation

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A mode of speciation occurring as the result of a radical change in the genome of a subpopulation, reproductively isolating the subpopulation from its parent population.

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Analogy

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Similarity between two species that is due to convergent evolution rather than to descent from a common ancestor with the same trait.

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Binomial

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The two part latinized name of a species, consisting of a genus and specific epithet.

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Clade

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A group of species that includes an ancestral species and all its descendants.

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Cladistics

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The analysis of how species may be grouped into clades.

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Cladogram

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A diagram depicting patterns of shared characteristics among species.

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Class

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In classification, the taxonomic category above order.

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Domain

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A taxonomic category above the kingdom level. The three domains are Archaea, Bacteria, and Eukarya.

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Family

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In classification, the taxonomic category above genus.

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Fossil record

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The chronicle of evolution over millions of years of geologic time engraved in the order in which fossils appear in rock strata.

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Genus

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A taxonomic category above the species level, designated by the first word of a species' two-part scientific name.

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Homoplasy

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Similar (analogous) structure or molecular sequence that has evolved independently in two species.

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In-group

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In a cladistic study of evolutionary relationships among taxa of organisms, the group that is actually being analyzed.

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Kingdom

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A taxonomic category, the second broadest after domain.

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Maximum likelihood

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A principle that states when considering multiple phylogenetic hypothesis, one should take into account the one that reflects the most likely sequence of evolutionary events, given certain rules about how DNA changes over time.

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Multiple parsimony

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A principle that states that when considering multiple explanations for an observation, one should first investigate the simplest explanation that is consistent with the facts.

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Molecular clock

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An evolutionary timing method based on the observation that at least some regions of genomes evolve at constant rates.

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Molecular systematics

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The comparison of nucleic acids or other molecules in different species to infer relatedness.

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Monophyletic

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Pertaining to a grouping of species consisting of an ancestral species and all its descendants; a clade.

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Neutral theory

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The hypothesis that much evolutionary change in genes and proteins has no effect on fitness and therefore is not influenced by Darwinian natural selection.

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Order

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In classification, the taxonomic category above family.

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Orthologous genes

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Homologous genes that are passed in a straight line from one generation to the next, but have ended up in different gene pools because of speciation.

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Out-group

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A species or group of species that is closely related to the group of species that is being studied, but clearly not as closely related as any study-group members are to each other.

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Paralogous genes

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Homologous genes that are found in the same genome due to gene duplication.

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Paraphyletic

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Pertaining to a grouping of species that consists of an ancestral species and some, but not all, of its descendants.

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Phylogenetic tree

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A branching diagram that represents a hypothesis about evolutionary organisms.

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Phylogeny

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The evolutionary history of a species or group of related species.

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Phylogram

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A phylogenetic tree in which the branches reflect the number of genetic changes that have taken place in a particular DNA or RNA sequence in the various lineages.

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Phylum

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In classification, the taxonomic category above class.

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Polyphyletic

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Pertaining to a group of species derived from two or more different ancestral forms.

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Shared derived character

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An evolutionary novelty that evolved within a particular clade.

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Shared primitive character

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A character displayed in species outside a particular taxon.

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Specific epithet

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The second part of a binomial, which is unique for each species in a genus.

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Systematics

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The analytical study of the diversity and relationships or organisms, both present day and extinct.

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Taxon

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The analytical study of the diversity and relationships of organisms, both present day and extinct.

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Ultrametric tree

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A phylogenetic tree in which the lengths of the branches reflect measurements of geologic time.