Question

Select incorrect statement w.r.t. inbreeding depression.
(A) It is associated with loss of vigor
(B) Appearance of a number of defective traits in normally self-pollinated plants
(C) It occurs due to an increase in homozygosity in recessive alleles
(D) A majority of cross-pollinated crops and all animals show inbreeding depression

Answer 1

Hint: Inbreeding depression is related to the decrease in fitness due to inbreeding. The most revealing impact of inbreeding is the physiological efficiency of an organism. The degree of inbreeding is equal to the degree of homozygosity.

Complete step by step answer:
Loss of characters because of continued self-pollination is termed inbreeding depression. The plants which have inbreeding depression are called inbred lines. Because of this, the loss of vigor takes place.
So, the correct answer is ‘It is associated with loss of vigor’.

Additional Information: Inbreeding depression is that the reduced biological fitness during a given population as a result of inbreeding, or breeding of related individuals. Population biological fitness is defined by an organism's ability to survive and make its genetic material continuously. Inbreeding depression is usually the result of a population bottleneck. generally, the higher the genetic variation or gene pool within a breeding population, the less likely it's to suffer from inbreeding depression. Inbreeding depression is seen to be present in many of the groups of organisms but it mostly varies across the mating systems. The lowest degree of inbreeding depression is shown by the hermaphroditic species that is lower than other species, as due to selfing occurring in the repeated generations removes deleterious alleles from populations. As an example, due to inbreeding depression, the severely suffered species is the outcrossing nematode (roundworm) Caenorhabditis remanei but it is not seen in the case of its hermaphroditic relative C. elegans, which experiences outbreeding depression.

Note: The biological effects of inbreeding depression in humans are mostly due to socioeconomic and cultural influences on reproductive behavior. Studies on human populations have shown that the age at which marriage is taking place, duration of the marriage, illiteracy, and reproductive compensation are the main factors of fertility, even amongst populations with a high proportion of consanguineous unions.