Which pollen transfer mechanism is often limited?

• A. Cross pollination
• B. Wind pollination
• C. Self pollination
• D. Pollination by water

Answer: (C)

Self-pollination transfers pollen within the same plant, so it doesn’t rely on external agents like pollinators or wind. That seems convenient, but it also means offspring are genetically very similar to the parent. Over generations this limited genetic variation can reduce fitness in changing environments or against new pests and diseases, a situation called inbreeding depression. Because of this, self-pollination is often restricted in the long term as a reproductive strategy. Some plants even have self-incompatibility systems that prevent selfing, further curbing its role. In contrast, cross-pollination and pollination by wind or water introduce new genetic combinations, which is why they’re favored in terms of evolutionary potential, even though they come with their own environmental constraints.