Terms in this set (18)
(al′ lo pat′ rick) [Gk. allos: other + patria: homeland] The formation of two species from one when reproductive isolation occurs because of the interposition of (or crossing of) a physical geographic barrier such as a river. Also called geographic speciation. (Contrast with sympatric speciation.)
The possession of more than two chromosome sets that are derived from more than one species.
The possession of more than two entire chromosomes sets that are derived from a single species.
biological species concept
The definition of a species as a group of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups. (Contrast with morphological species concept.)
A region of overlap in the ranges of two closely related species where the species may hybridize.
A series of populations, species, or genes descended from a single ancestor over evolutionary time.
lineage species concept
The definition of a species as a branch on the tree of life, which has a history that starts at a speciation event and ends either at extinction or at another speciation event. (Contrast with morphological species concept.)
morphological species concept
The definition of a species as a group of individuals that look alike. (Contrast with lineage species concept.)
(pol′ lee ploid ee) The possession of more than two entire sets of chromosomes.
postzygotic isolating mechanisms
Barriers to the reproductive process that occur after the union of the nuclei of two gametes. (Contrast with prezygotic isolating mechanisms.)
prezygotic isolating mechanisms
Barriers to the reproductive process that occur before the union of the nuclei of two gametes (Contrast with postzygotic isolating mechanisms.)
The evolution of enhanced reproductive isolation between populations due to natural selection for greater isolation.
Condition in which two divergent populations are no longer exchanging genes. Can lead to speciation.
Two species that are each other's closest relatives.
(spee′ see ay′ shun) The process of splitting one biological lineage into two biological lineages that evolve independently from one another.
(spee′ sees) [L. kind] The base unit of taxonomic classification, consisting of an ancestor-descendant group of populations of evolutionarily closely related, similar organisms. The more narrowly defined "biological species" consists of individuals capable of interbreeding with each other but not with members of other species.
Ways that biologists think about the existence of species.
(sim pat′ rik) [Gk. sym: same + patria: homeland] Speciation due to reproductive isolation without any physical separation of the subpopulation. (Contrast with allopatric speciation.)