Читать книгу Horse Genetics - Ernest Bailey - Страница 28

The classification of the Equidae is based on the Linnaean system as recommended through agencies of the nongovernmental organization the International Union for Conservation of Nature (IUCN). IUCN is devoted to global environmental science and the maintenance of biological diversity. When defining a biological species, scientists take into account physical characteristics and geographical distribution, as well as biological abilities to reproduce, behavioral barriers to reproduction, and genetic measures of evolutionary distance between populations. In former times, the separation of two populations by a mountain range may have been sufficient for the populations to have accumulated genetic, physical, and behavioral differences that merited their consideration as a discrete and unique population. In modern times, with pressure from growing human populations and mechanized travel, many small populations of animals have been pushed together, forcing the hybridization of groups of animals that had previously diverged significantly. As a result, precisely defining species and their characteristics can be challenging. Nevertheless, geneticists have been resourceful in applying a wide variety of techniques, including DNA sequencing, to discover and characterize the diverse species.