This glossary of genetics and evolutionary biology is a list of definitions of terms and concepts used in the study of genetics and evolutionary biology, as well as sub-disciplines and related fields, with an emphasis on classical genetics, quantitative genetics, population biology, phylogenetics, speciation, and systematics. Overlapping and related terms can be found in Glossary of cellular and molecular biology, Glossary of ecology, and Glossary of biology.
- 1. The dynamic process by which biological organisms develop characteristics that allow them to survive and reproduce within their environments.
- 2. The state or condition reached by a during that process.
- 3. Any character or with a functional role in an individual organism and which has evolved and is maintained through .
- The view that many or most physiological and behavioral traits of organisms are that have evolved for specific functions or for specific reasons (as opposed to being of the evolution of other traits, consequences of , or the result of random variation).
- adaptive radiation
- The simultaneous or near-simultaneous of multiple members of a single into a variety of different forms with different , especially a diversification in the use of resources or habitats.
- A species that does not reproduce but rather by cloning. Agamospecies are sometimes represented by that contain some diploid individuals and other apomictic forms—in particular, plant species that can reproduce via agamospermy.
- One of multiple alternative versions of an individual , each of which is a viable sequence occupying a given position, or , on a . For example, in humans, one allele of the eye-color gene produces blue eyes and another allele of the eye-color gene produces brown eyes.
- allele frequency
- The relative frequency with which a particular of a given (as opposed to other alleles of the same gene) occurs at a particular in the members of a population; more specifically, it is the proportion of all chromosomes within a population that carry a particular allele, expressed as a fraction or percentage. Allele frequency is distinct from , although they are related.
- allochronic isolation
- The isolation of two populations of a species due to a change in breeding periods. This isolation acts as a precursor to allochronic speciation, a type of which results when two populations of a species become isolated due to differences in reproductive timing. An example is the periodical 13- and 17-year Magicicada species.
- allo-parapatric speciation
- A mode of where divergence occurs in allopatry and is completed upon secondary contact of the populations--effectively a form of reinforcement.
- The comparative study of the relationship between the size of an organism's body (or of a specific organ, e.g. the brain) and various other biological characteristics, such as body shape, anatomy, physiology, or behavior.
- allopatric speciation
- A mode of where the evolution of is caused by the geographic separation of two or more of a single species.
- allopatric taxa
- Specific species that are distributed.
- The phenomenon by which two or more populations of a single species exist in geographic isolation from one another.
- A cell or organism in which the several sets of chromosomes originate from more than one , as in an intraspecific .
- allo-sympatric speciation
- A mode of where divergence occurs in and is completed upon of the populations–effectively a form of .
- Evolutionary change that occurs within a species lineage as opposed to lineage splitting ().
- analogous structures
- A set of structures in different organisms which have similar form or function but were not present in the organisms' . The cladistic term for the same phenomenon is homoplasy.
- ancestral trait
- For a given , any trait or feature (e.g. a specific ) that appears in the clade's ; the same trait may also appear in some or all of the lineal descendants included within the clade, indicating that it has undergone little or no significant change during the clade's evolutionary history and thus retained its "primitive" condition. Some but not all subgroups within the clade may contain , in which the ancestral trait has changed significantly over evolutionary time such that the original ancestral condition no longer exists. Both terms are relative: an ancestral trait for one clade may be a derived trait for a different clade. The term "ancestral trait" is often used interchangeably with the more technical term .
- A phenomenon by which the symptoms of a become apparent (and often more severe) at an earlier age in affected individuals with each generation that inherits the disorder.
- A state; i.e. the state or condition of a particular trait or feature (e.g. a specific ) that is distinct from and derivative of an by virtue of its modification over time in one or more lineal descendants of a given . Apomorphies are often viewed as evolutionary "innovations" which set the in which they appear apart from the clade's , as well as from other clades; apomorphies are used to construct and define clades. The term is relative; a trait considered an apomorphy in one clade may not be considered an apomorphy in a different clade. Contrast .
- Any character or that is currently subject to , whether its origin can be ascribed to selective processes () or to processes other than selection or selection for a function that is different from the current function ().
- area cladogram
- asexual reproduction
- associative overdominance
- The phenomenon by which the of a neutral locus to a selectively maintained causes the of the neutral locus to increase.
- assortative mating
- A in which individuals with similar mate with each other more frequently than would be expected in a completely random mating system. Assortative mating usually has the effect of increasing genetic relatedness between members of the mating population. Contrast .
- A modification of a biological structure whereby an suddenly reappears after having been lost through evolutionary change in previous generations. Atavisms can occur in a number of different ways, including by the re-expression of latent genes for ancestral phenotypes as a result of mutation, or by the shortening or prolongation of the time allocated for the of a particular trait during development.
- A cell or organism that is for a at which the two homologous are , both having been derived from a single gene in a . Contrast .
Also called functionalism.
Also called geographic speciation, vicariance, vicariant speciation, and dichopatric speciation.
Also called an ancestral character, primitive character, or primitive trait.
Also called positive assortative mating and homogamy.
- The breeding of a organism with one of its parents or an individual genetically similar to one of its parents, often intentionally as a type of , with the aim of producing offspring with a genetic identity which is closer to that of the parent. The reproductive event and the resulting progeny are both referred to as a backcross, often abbreviated in genetics shorthand with the symbol BC.
- Bateson–Dobzhansky–Muller model
- An evolutionary model of the genetic incompatibility that occurs as a result of negative interactions between two or more or with different evolutionary histories, which may meet when distinct populations . The incompatible genes or alleles themselves, referred to as Dobzhansky–Muller incompatibilities, may be the result of or neutral mutations, or they may be specific driven by . By preventing populations from successfully interbreeding, these incompatibilities can reinforce and thereby increase the chance of .
- behavioral isolation
- The scientific study of the spatial distributions of biological organisms, populations, and species. It includes the study of both extinct and extant organisms.
- biological constraints
- biological species concept
- See .
Also simply called the Dobzhansky–Muller model.