The evolution of self-fertilization in perennials

Area of Science:

• Evolutionary biology
• Plant reproductive strategies
• Life history evolution

Background:

• Self-fertilization (selfing) is common in plants, but its evolutionary implications in perennial species are understudied.
• Existing models often neglect key perennial life-history traits like longevity and adult inbreeding effects.
• A generalization suggests annual plants self-fertilize more than perennials, with reproductive assurance previously cited as a reason.

Purpose of the Study:

• To develop theoretical models incorporating perennial life-history traits into the study of self-fertilization.
• To investigate how adult inbreeding depression and survivorship costs affect the evolution of selfing in perennials.
• To re-evaluate the reasons behind the observed difference in selfing rates between annual and perennial plants.

Main Methods:

• Development of mathematical models simulating selfing in perennial plants.
• Inclusion of parameters for adult inbreeding depression and a survivorship cost linked to seed production.
• Analysis of how these factors influence the genetic transmission advantage of selfing over time.

Main Results:

• Adult inbreeding depression significantly reduces the evolutionary advantage of selfing in perennials.
• The negative impact of inbreeding depression is amplified in long-lived perennials over multiple seasons.
• Selfing can impose a cost on future reproduction and survivorship, outweighing benefits of increased seed set.

Conclusions:

• Perennial life history, particularly adult inbreeding depression and survivorship costs, provides a strong explanation for lower selfing rates compared to annuals.
• Reproductive assurance does not adequately explain the difference, as selfing offers similar assurance to both life forms.
• Perennials likely avoid selfing due to the substantial long-term fitness costs associated with inbreeding and reduced future reproductive capacity.