Question

Identify the mechanism that works for inbreeding _____________.

• A. Dioecism
• B. Selfing
• C. Monoecism
• D. Genetic self-incompatibility

Hint:

Selfing represents the most intense form of inbreeding possible in plants. Mechanisms like dioecism and self-incompatibility are evolutionary adaptations designed to prevent it.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Inbreeding is the mating of closely related individuals, which increases homozygosity and reduces genetic diversity.
In plants and forest trees, the most extreme form of inbreeding is self-pollination (selfing), where pollen fertilizes the female gamete of the same plant.

Step 2: Detailed Explanation:
Let us analyze the biological functions of each option to determine if they promote inbreeding or outbreeding:
- Dioecism: A condition where male and female flowers are borne on separate individual trees (e.g., in willow and poplar). This physical separation completely prevents selfing and forces cross-pollination (outbreeding).
- Selfing: The transfer of pollen from the anthers to the stigma of the same flower or another flower on the same plant. This is the direct reproductive mechanism that ensures and drives inbreeding.
- Monoecism: A condition where separate male and female flowers are found on the same tree (e.g., in conifers). While it can allow self-pollination (geitonogamy), it is often coupled with temporal separation (dichogamy) to reduce selfing and promote cross-pollination.
- Genetic self-incompatibility: A physiological and genetic mechanism that prevents a fertile hermaphrodite plant from setting seed when pollinated by its own pollen, actively blocking inbreeding.
Therefore, "Selfing" is the primary mechanism that functions to promote inbreeding.

Step 3: Final Answer:
The mechanism that works directly for inbreeding is Selfing.