Ecotype

There are three main groups of ecotypes:

• Climatic (geographical) - arise under the influence of climate change in various parts of the range. Characteristic mainly for species with wide ranges.
• Edaphic - are formed under the influence of soil and ground conditions.
• Biotic - arise under the influence of other organisms.

Experiments show that sometimes ecotypes appear only when they are separated by large spatial distances (about 1000 km). This is due to hybridization , as a result of which different but adjacent varieties of the same species (or, as a rule, of the same taxonomic rank ) interbreed, thereby overcoming local selection. However, other studies show that the opposite can happen, that is, ecotypes found on very small scales (about 10 m) and populations ^[2] .

In ecotypes, continuous, gradual geographical variations are characterized by the imposition of similar phenotypic and genetic variations ^[2] . This situation is called ecocline. A well-known example of ecocline is the gradation of skin color in indigenous people around the world, which is associated with the latitude and amount of sunlight ^[3] . But often the distribution of ecotypes is bimodal or multimodal. This means that ecotypes can display two or more different and discontinuous phenotypes even within the same population. Such a phenomenon can lead to speciation and can occur if conditions in the local environment change sharply in space or time ^[2] .

• Tundra deer and forest deer are two reindeer ecotypes. The former migrate (covering 5000 km) annually between two environments in large numbers, while the others (which are much smaller) remain in the forest for the summer ^[4] . In North America, the species Rangifer tarandus, locally known as caribou ^{[5] [6]} , was divided into five subspecies. Caribou are classified by ecotype depending on several behavioral factors - the predominant use of the habitat (north, tundra, mountains, forest, boreal forest, forest dwelling), distance (scattered or aggregated) and migration (sedentary or migratory) ^{[7] [8] [9]} . For example, the subspecies Rangifer tarandus caribou is also distinguished by a number of ecotypes, including boreal forest caribou, mountain forest caribou and migratory forest caribou.

• Rezuha (Arabis fecunda), grass endemic to some calcareous soils of Montana , USA . It can be divided into two ecotypes. One “low-altitude” group lives near the earth in an arid, warm environment and, thus, has significantly greater drought resistance than the “high-altitude” group. Two ecotypes are separated by a horizontal distance of about 100 km ^[2] .

• It is generally accepted that the white dolphin has two ecotypes — the river ecotype found in some rivers of South America and the pelagic ecotype found in the southern Atlantic Ocean ^[10] . Similarly, bottlenose dolphins have two ecotypes in the western North Atlantic .

• Scots pine (Pinus sylvestris) has 20 different ecotypes in the region from Scotland to Siberia , capable of crossbreeding ^[11] .

• Scientists discovered a very unusual case in snails: it was noticed that two populations of the same Helix snail, separated by only a few hundred kilometers, prefer not to cross, that is, they reject each other as a mating partner. This event probably occurs during the courtship process, which can last for hours.

• Ecotype - an article from the Great Soviet Encyclopedia .