Түр ішіндегі экологиялық түрлер жіктелуі

Classification of distinct populations lesser than subspecies

In evolutionary ecology, an ecotype, sometimes called ecospecies, describes a genetically distinct geographic variety, population, or race within a species, which is genotypically adapted to specific environmental conditions. Typically, though ecotypes exhibit phenotypic differences (such as in morphology or physiology) stemming from environmental heterogeneity, they are capable of interbreeding with other geographically adjacent ecotypes without loss of fertility or vigor.

An ecotype is a variant in which the phenotypic differences are too few or too subtle to warrant being classified as a subspecies. These different variants can occur in the same geographic region where distinct habitats such as meadow, forest, swamp, and sand dunes provide ecological niches. Where similar ecological conditions occur in widely separated places, it is possible for a similar ecotype to occur in the separated locations. An ecotype is different from a subspecies, which may exist across a number of different habitats. In animals, ecotypes owe their differing characteristics to the effects of a very local environment. Therefore, ecotypes have no taxonomic rank.

Experiments indicate that sometimes ecotypes manifest only when separated by great spatial distances (of the order of 1,000 km). This is due to hybridization whereby different but adjacent varieties of the same species (or generally of the same taxonomic rank) interbreed, thus overcoming local selection. However other studies reveal that the opposite may happen, i. e., ecotypes revealing at very small scales (of the order of 10 m), within populations, and despite hybridization. But often the distribution of ecotypes is bimodal or multimodal. This means that ecotypes may display two or more distinct and discontinuous phenotypes even within the same population. Such phenomenon may lead to speciation and can occur if conditions in a local environment change dramatically through space or time. In North America, the species Rangifer tarandus (locally known as caribou), was subdivided into five subspecies by Banfield in 1961. Caribou are classified by ecotype depending on several behavioural factors – predominant habitat use (northern, tundra, mountain, forest, boreal forest, forest dwelling), spacing (dispersed or aggregated) and migration (sedentary or migratory). For example, the subspecies Rangifer tarandus caribou is further distinguished by a number of ecotypes, including boreal woodland caribou, mountain woodland caribou, and migratory woodland caribou (such as the migratory George River Caribou Herd in the Ungava region of Quebec). Arabis fecunda, a herb endemic to some calcareous soils of Montana, United States, can be divided into two ecotypes. The one "low elevation" group lives near the ground in an arid, warm environment and has thus developed a significantly greater tolerance against drought than the "high elevation" group. The two ecotypes are separated by a horizontal distance of about Similarly, it is accepted that the common bottlenose dolphin has two ecotypes in the western North Atlantic. The warbler finch and the Cocos Island finch are viewed as separate ecotypes. The Scots pine (Pinus sylvestris) has 20 different ecotypes in an area from Scotland to Siberia, all capable of interbreeding. Ecotype distinctions can be subtle and do not always require large distances; it has been observed that two populations of the same Helix snail species separated by only a few hundred kilometers prefer not to cross mate, i. e., they reject one another as mates. This event probably occurs during the process of courtship, which may last for hours.