Sympatry in the context of Parapatric speciation

In biology, a ring species is a connected series of neighbouring populations, each of which interbreeds with closely sited related populations, but for which there exist at least two end populations in the series which are too distantly related to interbreed, though there is a potential gene flow between linked neighbouring populations. Such non-breeding, though genetically connected, end populations may co-exist in the same region (sympatry) thus closing a ring. The German term Rassenkreis, meaning "circle of races", is also used.

Ring species represent speciation and have been cited as evidence of evolution. They illustrate what happens over time as populations genetically diverge, specifically because they represent, in living populations, what normally happens over time between long-deceased ancestor populations and living populations, in which the intermediates have become extinct. The evolutionary biologist Richard Dawkins remarks that ring species "are only showing us in the spatial dimension something that must always happen in the time dimension".

Apis cerana, the eastern honey bee, Asiatic honey bee or Asian honey bee, is a species of honey bee native to South, Southeast and East Asia. This species is the sister species of Apis koschevnikovi and both are in the same subgenus as the western (European) honey bee, Apis mellifera. A. cerana is known to live sympatrically along with Apis koschevnikovi within the same geographic location. Apis cerana colonies are known for building nests consisting of multiple combs in cavities containing a small entrance, presumably for defense against invasion by individuals of another nest. The diet of this honey bee species consists mostly of pollen and nectar, or honey. Moreover, Apis cerana is known for its highly social behavior, reflective of its classification as a type of honey bee.

The terms Apis cerana indica and Apis Indica or Indian honey bee, is an historic term, with all Asian hive bees now referred to as Apis cerana.

Apis koschevnikovi, Koschevnikov's honey bee, is a species of honey bee which inhabits Malaysian and Indonesian Borneo, where it lives sympatrically with other honey bee species such as Apis cerana (specifically A. c. nuluensis).

The species was first described by Hugo Berthold von Buttel-Reepen, who dedicated it to Grigory Aleksandrovich Kozhevnikov (1866–1933), a pioneer of honey bee morphology. This was an invalid designation, however, and the name was first formally made available by Günther Enderlein that same year. Therefore, Buttel-Reepen is not the author of the name (following the ICZN). The species was described again by Maa in 1953, this time with the name Apis vechti. It was finally rediscovered by Tingek and his colleagues in 1988.

Sympatric speciation is the evolution of a new species from a surviving ancestral species while both continue to inhabit the same geographic region. In evolutionary biology and biogeography, sympatric and sympatry are terms referring to organisms whose ranges overlap so that they occur together at least in some places. If these organisms are closely related (e.g. sister species), such a distribution may be the result of sympatric speciation. Etymologically, sympatry is derived from Greek συν (sun-) 'together' and πατρίς (patrís) 'fatherland'. The term was coined by Edward Bagnall Poulton in 1904, who explains the derivation.

Sympatric speciation is one of three traditional geographic modes of speciation. Allopatric speciation is the evolution of species caused by the geographic isolation of two or more populations of a species. In this case, divergence is facilitated by the absence of gene flow. Parapatric speciation is the evolution of geographically adjacent populations into distinct species. In this case, divergence occurs despite limited interbreeding where the two diverging groups come into contact. In sympatric speciation, there is no geographic constraint to interbreeding. These categories are special cases of a continuum from zero (sympatric) to complete (allopatric) spatial segregation of diverging groups.

The rhinoceros iguana (Cyclura cornuta) is an endangered species of iguana that is endemic to the Caribbean island of Hispaniola (shared by Haiti and the Dominican Republic) and its surrounding islands. A large lizard, they vary in length from 60 to 136 centimetres (24 to 54 in), and skin colours range from a steely grey to a dark green and even brown. Their name derives from the bony-plated pseudo-horn or outgrowth which resembles the horn of a rhinoceros on the iguana's snout. It is known to coexist with the Ricord's iguana (C. ricordii); the two species are the only taxa of rock iguana to do so.

The hispid hare (Caprolagus hispidus), also known as the Assam rabbit and bristly rabbit, is a species of rabbit native to South Asia. It is the only species in the genus Caprolagus. Named for its bristly fur coat, the hispid hare is a rabbit with dark-brown fur and a large nose. It has small ears compared to the Indian hare, a lagomorph that occurs in the same regions as the hispid hare.

Once thought to be extinct, the hispid hare was rediscovered in Assam in 1971 and has been found in isolated populations across India, Nepal, and Bangladesh. Its historic range extended along the southern foothills of the Himalayas, and a related fossil in the genus Caprolagus has been found as far away as Indonesia. Today, the species' habitat is much smaller and is highly fragmented. The region it occupies is estimated to be less than 500 square kilometres (190 sq mi), extending over an area of 5,000 to 20,000 square kilometres (1,900 to 7,700 sq mi). Populations experienced a continuing decline due to loss of suitable habitat via increasing agriculture, flood control, and human development, particularly burning and collection of thatch grasses. It has been listed as Endangered on the IUCN Red List since 1986. The rabbit is known to occur in several national parks. Breeding in captivity has been described as "very difficult". Conservation efforts focus on community education and further study.