Question: Which of the following is the first step in allopatric speciation?
A Genetic drift
B Geographical isolation
C Polyploidy
D Hybridization
Answer: Geographical isolation
| Steps in allopatric speciation | Description |
| Geographic Isolation | · Populations of a single species become physically separated by a geographic barrier, such as a mountain range, river, or ocean.
· This isolation prevents gene flow between the separated populations. |
| Genetic Divergence | · In each isolated population, genetic changes and mutations accumulate independently over time.
· These genetic differences can lead to changes in allele frequencies and the emergence of distinct traits. |
| Adaptation to Environment | · Isolated populations may undergo adaptive changes to better suit their respective environments.
· Natural selection acts on genetic variation, leading to different adaptations and traits in each population. |
| Reproductive Isolation | · Over time, genetic differences between the two populations can lead to reproductive barriers, making interbreeding between them less likely or impossible.
· These barriers can be prezygotic (preventing mating or fertilization) or postzygotic (reducing the fitness of hybrid offspring). |
| Speciation Event | · When the two isolated populations can no longer interbreed and produce viable, fertile offspring, they are considered as distinct species.
· Allopatric speciation is complete, resulting in two or more separate species. |