Difference between Allopatric and Sympatric Speciation

Allopatric vs Sympatric speciation

The process of origin of new species is called speciation. The formation of new species from existing species can occur in two ways; sympatrically or allopatrically.

Allopatric speciation (‘Allo’: different, ‘patris’: country)

• Speciation occurs when the population becomes separated by geographical barriers like mountains, rivers etc.
• Thus the chance of interbreeding between these populations is greatly reduced.
• Each population acquires mutations by natural selection to adapt to the new environment. After a long time, reproductive isolation sets in separating two populations into two species.
• Geographical isolation leads to reproductive isolation and speciation.
• This is the most common form of speciation.

Sympatric speciation (‘Sym’: same or together, ‘patris’: country)

• It is the formation of two or more species from a single ancestral species all occupying the same geographical area.
• In sympatric speciation, the populations are not geographically separated.
• Sympatric speciation often occurs through polyploidy. A diploid individual cannot interbreed with tetraploid individual leading to reproductive isolation.
• This type of speciation is rare and occurs often in plants as self fertilization and polyploidy is common in plants compared to animals.