Read the following statements and choose the correct option.(i)Increas...
Melanised moths and natural selection:
The statement (i) is correct. The increase in melanised moths after industrialisation in Great Britain is indeed a proof for natural selection. Before industrialisation, the majority of moths in Britain were light-colored (non-melanised) because they blended well with the lichen-covered trees. However, with the onset of industrial pollution, the lichens died out, and the trees became darkened with soot. This led to an increase in the number of melanised (dark-colored) moths as they were better camouflaged against the new background. This change in the moth population over time is an example of natural selection, where individuals with advantageous traits are more likely to survive and reproduce.
Mean character value and disruption:
The statement (ii) is incorrect. The term "disruption" refers to a type of natural selection where individuals with extreme or divergent traits have higher fitness than those with intermediate traits. This can lead to the splitting of a population into two distinct groups or the formation of multiple phenotypic clusters. It does not involve the acquisition of a mean character value by more individuals.
Allelic frequency and Hardy-Weinberg equilibrium:
The statement (iii) is incorrect. Changes in allelic frequency in a population do not necessarily lead to Hardy-Weinberg equilibrium. The Hardy-Weinberg equilibrium describes a theoretical population in which the allelic frequencies remain constant from generation to generation in the absence of evolutionary forces like mutation, migration, selection, and genetic drift. Any change in allelic frequency indicates that the population is not in Hardy-Weinberg equilibrium.
Genetic drift and gene frequency:
The statement (iv) is correct. Genetic drift refers to the random fluctuations in gene frequencies within a population due to chance events, particularly in small populations. These chance events can lead to the loss or fixation of certain alleles over time, resulting in changes in the existing gene or allelic frequencies in future generations. Genetic drift is one of the mechanisms of evolution and can have significant effects on the genetic diversity of populations.
Therefore, the correct option is (c) both (i) and (iv) are correct.
Read the following statements and choose the correct option.(i)Increas...
When more individuals of a population acquire a mean character value, it is called stabilising selection. No change in allelic frequency in a population will lead to Hardy-Weinberg equilibrium.