Question

Discuss the major differences among allopatric, parapatric, and sympatric speciation.

Short answer

Allopatric speciation occurs when a population splits into separate groups due to a physical barrier leading to their evolution into different species. Parapatric speciation happens when two populations evolve into distinct species whilst remaining in contact along their border, with reduced gene flow due to differing environmental selection pressures. Sympatric speciation is when a new species evolves from a single ancestral species while inhabiting the same geographic region, often due to differences in behaviors or diets, or genetic mutations leading to reproductive isolation.

Step-by-step solution

Explain Allopatric Speciation

In allopatric speciation, a physical barrier - like a mountain range or body of water - splits a population into two or more separate groups. Over time, these isolated populations develop distinct genetic and phenotypic characteristics due to the variations in the environment or breeding patterns within each group. As they evolve, the populations become so different that they can no longer breed with each other, thus becoming different species.

Explain Parapatric Speciation

Parapatric speciation occurs when two subpopulations of a species evolve into separate species while remaining in contact along a common border. This can occur due to different selection pressures in their respective environments. Despite being in close proximity, gene flow between the two populations is reduced, leading to the development of different phenotypes and ultimately distinct species.

Explain Sympatric Speciation

Sympatric speciation occurs when a new species evolves from a single ancestral species while inhabiting the same geographic region. Here, reproductive isolation occurs without any physical barriers. This can happen due to differences in mating preferences or habits, diets or a genetic mutation leading to reproductively isolated groups.