Gene flow and species delimitation

A defining feature of species is that their constituting populations are connected by gene flow. However, interspecific gene flow (introgression) can affect species integrity. If some genome components were less prone to introgression than others, they should be particularly suitable to delimitate species. Recent simulation studies have predicted a negative correlation between intra- and interspecific gene flow, suggesting that markers associated with the most dispersing sex should better delimitate species. A review of studies of introgression in species with sex-biased dispersal largely confirms this prediction. Hence, species delimitation should be more effective with markers experiencing high levels of gene flow, a simple but not widely appreciated prediction. A defining feature of species is that their constituting populations are connected by gene flow. However, interspecific gene flow (introgression) can affect species integrity. If some genome components were less prone to introgression than others, they should be particularly suitable to delimitate species. Recent simulation studies have predicted a negative correlation between intra- and interspecific gene flow, suggesting that markers associated with the most dispersing sex should better delimitate species. A review of studies of introgression in species with sex-biased dispersal largely confirms this prediction. Hence, species delimitation should be more effective with markers experiencing high levels of gene flow, a simple but not widely appreciated prediction. refers to the geographic separation of different populations. any of several related statistical methods using genetic information to ascertain population membership of individuals. the use of short, standardised DNA sequences to quickly and easily identify and discover species. discrete models consisting of a regular grid of cells, each in one of a finite number of states; the state of a cell is a function of the states of neighbouring cells in the previous generation, and every cell has the same updating rule. in taxonomy, a marker or trait is said to be diagnostic if it presents different character states in different taxa. the number of breeding individuals in an idealised population that would show the same amount of genetic drift or the same amount of inbreeding as the population under consideration. in philosophy, the view that, for any specific kind of entity, there is a set of permanent and unalterable characteristics or properties that any entity of that kind must possess. movement of genes among populations due to the combined effects of dispersal and selective processes. movement of genes among populations due to dispersal processes. the process by which a neutral allele increases in frequency because it is linked to a beneficial allele under positive selection. the permanent incorporation of genes from one set of differentiated populations into another. a model in which genetic drift predominates and where selective effects can be ignored, generally because selection coefficients are small relative to population size. refers to populations living in nearby geographic areas. the tendency for an animal to breed in the vicinity of its birthplace. when a group does not include the most recent common ancestor of all its members. darwinian selection resulting in the increased frequency of a beneficial mutation (i.e. a mutation characterised by a positive selection coefficient). rapid increase in frequency of a genomic region under positive selection, resulting in its spread across the species range. refers to an imbalance in the dispersal behaviour of the males and females of a species, leading to a markedly higher dispersal of one of the two sexes (i.e. male-biased or female-biased dispersal). evolution of reproductive barriers as well as phenotypic, behavioural and genetic differences between populations, eventually leading to distinct species. refers to the spread of an allele by the wave of advance of a range expansion. refers to populations living in the same geographic areas.