speciation is the term used to refer to the division of a lineage. what produces two or more species many different. In a nutshell, we can say that it is the process of emergence of a new species, and the crucial event for this to happen is reproductive isolation. This reproductive isolation impedes gene flow, therefore, obeying the biological species concept, we say that a new species has emerged.
→ How does speciation occur?
There are three basic types of speciation:
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Allopatric:Allopatric speciation is about à speciation by geographic isolation. In this case, we have a physical barrier or a large distance (geographical barrier) that arises preventing contact between individuals who previously belonged to the same population. This separation causes individuals to be prevented from mating, leading to a decrease in gene flow. As they undergo different selective pressures, changes are observed in these organisms, in addition to the possibility of reproductive isolation mechanisms, leading to speciation. This type of speciation is the most accepted model for the emergence of new animal species.
Founding effect or peripatric speciation: A special type of allopatric speciation is when a small group of individuals separates from the original large population. In these small populations, speciation occurs faster due to the action of genetic drift. However, due to the reduced number of individuals, what usually occurs is their extinction.
Sympatric: Sympatric speciation occurs without geographic separation. In this case, two populations coexist in the same territory, but there is no crossing between individuals from different populations. Usually, early on, there are changes that prevent crossover, so there is a early reproductive isolation.
Parapatric: In this type of speciation, there are two populations living in contiguous areas with ecological differences, without the existence of any geographical barrier. In this case, one can see a contact region where there is crossing, leading to the emergence of hybrid individuals and the lack of interbreeding at the extremes of the population. The hybrid zone can act as a barrier, preventing gene flow between populations that are differentiating.
By Ma. Vanessa dos Santos
Source: Brazil School - https://brasilescola.uol.com.br/o-que-e/biologia/o-que-e-especiacao.htm
