Question

Variation combined with geographical isolation may result in
A. Mutation
B. Speciation
C. Fossilisation
D. Genetic drift

Answer 1

Hint: Geographical isolation refers to the population of animals, plants, or other organisms that are separated from exchanging genetic material with other organisms of the same species.

Complete Answer:
Let us analyze each option to find out the correct answer.
Option A: Mutation can be defined as any sudden inheritable change in the DNA sequences either due to mistakes when DNA replicates or environmental factors such as UV rays, cigarette smoking, etc. The mutation is an alteration in the genetic material. Therefore, this is an incorrect option.

Option B: Speciation occurs when a single species becomes geographically separated into two populations. Hence, the individuals cannot travel between the populations, preventing the two populations from interbreeding. As a result, two populations cannot exchange genes, and because of different environmental conditions, they slowly evolve differences. Eventually, the two populations become different enough that they do not interbreed even if they come into contact (reproductively isolated), and are, therefore, two separate species. Therefore, this is the correct option.

Option C: Fossilisation refers to the preservation of traces of life in the geological record. It is the process in which a once-living organism becomes a fossil. Therefore, this is an incorrect option.

Option D: Genetic drift is defined as a mechanism of evolution in which allele frequencies of a population change over generations due to chance (sampling error). It is to be noted that it occurs in all populations of non-infinite size, but its effects are strongest in small populations. Therefore, this is an incorrect option.

Thus, the correct option is B) Speciation.

Note: Variation refers to the differences between two individuals, as each individual is unique and possesses different characteristic traits. It is to be noted that the three causes of variation are mutation, recombination and immigration of genes.