Sympatric speciation is the formation of species within a single population without geographical isolation. Thus the sub population become reproductively isolated in the midst of its parental population. Such species are also called sibling species. Sibling species one of two or more species that closely resemble one another but whose members cannot interbreed successfully .

The correct answer is option D: sibling species.

Sibling species are populations that are closely related morphologically and ecologically, but are reproductively isolated from each other. They have evolved from a common ancestral population and have diverged to the point where they can no longer interbreed and produce viable offspring.

Explanation:

Morphologically similar populations:
Sibling species are morphologically similar, meaning they have similar physical characteristics and traits. This similarity can make it difficult to distinguish them based on external appearance alone. They may have similar body shapes, coloration, or other physical features.

Sympatric populations:
Sympatric populations are populations that coexist in the same geographic area or habitat. In the case of sibling species, they can be found in the same location or habitat but are reproductively isolated from each other.

Reproductive isolation:
Reproductive isolation refers to mechanisms or barriers that prevent individuals from different populations or species from successfully mating and producing viable offspring. These barriers can be prezygotic (occurring before fertilization) or postzygotic (occurring after fertilization).

In the case of sibling species, they have evolved reproductive barriers that prevent them from interbreeding and producing viable offspring. These barriers can be behavioral, ecological, temporal, or genetic. For example, they may have different mating behaviors, occupy different ecological niches, have different mating seasons, or have genetic incompatibilities that prevent successful reproduction.

Designation as sibling species:
Sibling species are designated as such because they are recognized as separate species despite their morphological similarity and sympatric distribution. This designation is based on the fact that they are reproductively isolated and have evolved distinct genetic and ecological characteristics.

It is important to note that sibling species can still have some level of genetic exchange, such as occasional hybridization or introgression. However, these events are relatively rare and do not result in the formation of a single population.

In conclusion, the closely related morphologically similar sympatric populations that are reproductively isolated are designated as sibling species because they have evolved distinct genetic and ecological characteristics despite their physical similarities.

Is not it c?