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Speciation is the evolutionary process by which populations evolve to become distinct species.The biologist Orator F. Cook coined the term in 1906 for cladogenesis, the splitting of lineages, as opposed to anagenesis, phyletic evolution within lineages.
In sympatric speciation, selection against hybrids is required; therefore reinforcement can play a role, given the evolution of some form of fitness trade-offs. [1] In sympatry, patterns of strong mating discrimination are often observed—being attributed to reinforcement. [7] Reinforcement is thought to be the agent of gametic isolation. [27]
[1] [2] Evidence for speciation by reinforcement has been gathered since the 1990s, and along with data from comparative studies and laboratory experiments, has overcome many of the objections to the theory. [3]: 354 [4] [5] Differences in behavior or biology that inhibit formation of hybrid zygotes are termed prezygotic isolation.
In essence, sympatric speciation does require very strong forces of natural selection to be acting on heritable traits, as there is no geographic isolation to aid in the splitting process. Yet, recent research has begun to indicate that sympatric speciation is not as uncommon as was once assumed.
A speciation event produces orthologs in the two daughter species (human and chimpanzee). Bottom: in a separate species ( E. coli ), a gene has a similar function ( histone-like nucleoid-structuring protein ) but has a separate evolutionary origin and so is an analog .
Allopatric speciation (from Ancient Greek ἄλλος (állos) ' other ' and πατρίς (patrís) ' fatherland ') – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model [1]: 86 – is a mode of speciation that occurs when biological populations become geographically isolated from each other to an extent that prevents or interferes with ...
Also called geographic speciation, vicariance, vicariant speciation, and dichopatric speciation. A mode of speciation where the evolution of reproductive isolation is caused by the geographic separation of two or more populations of a single species. [5] allopatric taxa Specific species that are allopatrically distributed. allopatry
Parapatric speciation, in which two diverging populations are separate but do overlap somewhat; partial separation is afforded by geography, so individuals of each species may come in contact from time to time, but selection for specific behaviors or mechanisms may prevent breeding between the two groups.