Question

Continued self-pollination results in:
A. Inbreeding depression
B. Self-incompatibility
C. Formation of unisexual flowers
D. Loss of vigor in gametes

Answer 1

Hint: Pollination is defined as the mechanism which brings the male and the female gametes in plants together which ultimately leads to fertilization.
In plants, there is a phenomenon known as autogamy, which refers to the transfer of pollen grains to stigma within the same flower. This is synonymous to self-pollination, and another concept called inbreeding. We shall understand the concept better in the next paragraph.

Complete answer:
Now, to ensure autogamy, plants have developed certain adaptations like:
1. Bisexuality: Presence of both the whorls (androecium and gynoecium) in the same flower.
2. Homogamy: Maturation of androecium and gynoecium in the same time so that when the pollen grains are released, then the stigma is ready to accept them.
3. Cleistogamy: This is a condition in which the flower does not open. The androecium and gynoecium mature in the closed flower and the pollination is completed at that stage only.
Now, autogamy may be useful for plants in that it does not require pollinating agents, and also the plants do not need to produce costly nectar and fragrances to attract the pollinating agents. But still, it has some disadvantages from the evolutionary point of view.
Since, there is no random mating as the flowers are self-pollinated, so this reduces the chances of genetic variability.
The concept of breeding is well known in animal husbandry practices. Here, Inbreeding refers to that concept where mating is allowed in between similar breeds having common ancestors for at least 4-6 generations. This increases the homozygosity of the race. Continuous inbreeding reduces fertility, production, and immunity of the animals to natural calamities. It reduces variations and thus chances of developing adaptations with the ever-changing environment. This is known as inbreeding depression.
The same phenomenon occurs in plants. The plants also lose their chances of variations, and thus the race is lost soon in the near future. Random mating is essential from the point of evolutionary aspects.

Hence, Option-A) Inbreeding depression is the correct answer.

Note:
The point to be noted here is that in plants, geitonogamy occurs, which is genetically similar to autogamy, or self-pollination. It is defined as the transfer of pollen grains from anther to the stigma of another flower of the same plant. Thus, the concept is the same. The pollen grains combine with the eggs having the same genome. Thus, here also, inbreeding depression can creep in due to absence of random mating.