In the 1940s, Ernst Mayr coined the term Biological Species Concept that was subsequently widely embraced by the scientific community. The definition stated that "Species are groups of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups". Certain mechanisms are in place to prevent species from interbreeding with others and these are referred to as reproductive isolating mechanisms, which are biological incompatibilities. There are many mechanisms acting on natural populations and these are broadly grouped into two categories namely prezygotic and postzygotic mechanisms.
Prezygotic isolating mechanisms are those mechanisms that isolate species before fertilisation i.e. before a zygote is formed. They include geographical, ecological, temporal, ethological, mechanical, morphological and gametic isolation. These mechanisms lesson the possibility of gametes from different species coming into contact and hence forming a zygote.
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