Many Plants Have Evolved Self-Incompatibility Mechanisms to Increase Genetic Variation Within a Species
- Imagine a garden filled with vibrant flowers.
- Now, consider what would happen if each flower only pollinated itself.
- Over time, the garden would lose its diversity and resilience.
- This is why many plants have evolved self-incompatibility mechanisms to prevent self-pollination and promote genetic diversity.
Definition
Self-incompatibility
A genetic mechanism in plants that prevents self-pollination by rejecting pollen from the same plant or genetically similar individuals.
The Problem with Inbreeding
- Self-pollination occurs when pollen from a flower fertilizes the ovules of the same plant.
- While this ensures reproduction, it leads to inbreeding, which has several drawbacks:
- Reduced Genetic Diversity: Offspring are genetically similar to the parent, limiting variation.
- Inbreeding Depression: Increased likelihood of harmful recessive traits, leading to weaker plants.
- Think of a sports team where all players have the same skills.
- They might perform well in one situation but struggle to adapt to new challenges.
- Similarly, plants that self-pollinate lack the genetic flexibility to thrive in changing environments.
The Benefits of Cross-Pollination
- Cross-pollination which is the transfer of pollen between different plants offers several advantages:
- Increased Genetic Variation: Offspring inherit diverse traits, enhancing adaptability.
- Hybrid Vigour: Cross-pollinated plants often grow stronger and healthier.
Think of vigor as a measure of an organism's robustness or vitality in response to environmental conditions.
TipCross-pollination is especially crucial in changing environments, where genetic diversity increases the chances of survival.
How Self-Incompatibility Works
Genetic Mechanisms
- Self-incompatibility is a genetic system that prevents self-pollination.
- It operates through two main mechanisms:
- Gametophytic Self-Incompatibility (GSI): The pollen is rejected based on its own genetic makeup.
- Sporophytic Self-Incompatibility (SSI): The pollen is rejected based on the genetic makeup of the parent plant.
