IB 160: Evolution.

2001

BIOLOGICAL SPECIES CONCEPT:

A species is a group of individuals fully fertile inter se (ie: among themselves), but barred from interbreeding with other similar groups by it physiological properties (producing either incompatibility of parents, or sterility of the hybrids, or both) (Dobzhansky, 1935).

Species are groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other such groups (Mayr, 1942).

EVOLUTIONARY SPECIES CONCEPT:

A species is a single lineage of ancestral descendant populations or organisms which maintains its identity from other such lineages and which has its own evolutionary tendencies and historical fate (Wiley, 1978).

PHYLOGENETIC SPECIES CONCEPT:

A phylogenetic species is an irreducible (basal) cluster of organisms that is diagnosably distinct from other such clusters, and within which there is a parental pattern of ancestry and descent (Cracraft, 1989).

A species is the smallest monophyletic group of common ancestry (de Quieroz and Donoghue, 1990).

RECOGNITION SPECIES CONCEPT:

Species are the most inclusive population of individual biparental organisms which share a common fertilization system (Patterson, 1985).

COHESION SPECIES CONCEPT:

A species is the most inclusive population of individuals having me potential for phenotypic cohesion through intrinsic cohesion mechanisms (Templeton, 1989).

ECOLOGICAL SPECIES CONCEPT:

A species is a lineage (or a closely related set of lineages) which occupies an adaptive zone minimally different from that of any other lineage in its range and which evolves separately from all lineages outside its range (Van Valen, 1976).

INTERNODAL SPECIES CONCEPT:

Individual organisms are conspecific in virtue of their common membership of a part of the genealogical network between two permanent-splitting events or between a permanent split and an extinction event (Kornet, 1993).