Question

Which one of the following is the first in allopatric speciation?
(a) Geographic isolation
(b) Hybridisation
(c) Genetic drift
(d) Polyploidy

Answer 1

Allopatric speciation occurs when populations of the same species are isolated due to changes in areas such as mountain building or changes as emigration. Isolation can arise due to the formation of mountains, continents, islands, or by human activity as agriculture. Speciation is a process by which populations evolve into different species.

Complete answer:
Geographic isolation is the first step in allopatric speciation. In the Greek language, allos means others and patris refers to the fatherland. Geographic isolation in allopatric speciation happens to an extent that prevents gene flow i.e., organisms are separated from exchanging genetic materials. Allopatric speciation is a dynamic process.

Additional Information: -Geographic isolation leads to the creation of barriers that prevent the exchange of genetic information between the two populations leading to reproductive isolation.
-If the two populations come into contact they will be unable to reproduce. Other factors such as population dispersal leading to emigration(moving out of individuals from an area) are considered a special case of allopatric speciation called peripatric speciation.
Hybridization- Hybridisation is the successful mating of different individuals of genetically isolated populations.
Genetic drift- Genetic drift is the change in frequency of the existing genes in a population due to random mating in a population.
Polyploidy- Polyploidy is a condition wherein the cells of an organism have more than two paired sets of chromosomes.
So, the correct answer is geographical isolation.

Note: The populations after geographical isolation undergo genetic changes and mutations in the separated gene pools. This is a concept used in evolution theory. The barriers prevent genetic material exchange and this leads to reproductive isolation. The founder effect focuses mainly on small geographically isolated populations.