THE EFFECTS OF SELECTION IN THE GAMETOPHYTE STAGE ON MUTATIONAL LOAD

Area of Science:

• Evolutionary genetics
• Plant population genetics
• Molecular evolution

Background:

• Inbreeding depression is a significant factor in the maintenance of outcrossing in seed plants.
• Mutations can affect both diploid sporophyte and haploid pollen stages in plants.
• Understanding the impact of selection on pollen is crucial for plant breeding and conservation.

Purpose of the Study:

• To investigate how selection in the pollen stage reduces inbreeding depression in the sporophyte.
• To analyze the relationship between pollen fitness and diploid progeny fitness.
• To evaluate the effectiveness of pollen selection in improving plant fitness.

Main Methods:

• Utilized a multilocus selection model for plant populations.
• Incorporated mutations affecting both sporophyte and pollen stages.
• Modeled the covariance between pollen and zygote fitnesses.

Main Results:

• A positive covariance between pollen and zygote fitnesses was observed, as intuitively expected.
• This covariance is predicted to be small.
• Strong selection on pollen is expected to result in only slight increases in sporophyte fitness.

Conclusions:

• Selection acting on the haploid pollen stage can mitigate inbreeding depression.
• The impact of pollen selection on overall sporophyte fitness is likely modest.
• Further research can compare these theoretical findings with experimental observations of pollen selection.