Sex-specific selection patterns in a dioecious insect-pollinated plant

Area of Science:

• Evolutionary Biology
• Plant Reproductive Ecology
• Sexual Selection

Background:

• Mate acquisition competition is fundamental to sexual organisms.
• Insect-pollinated plants face pollinator competition, potentially influencing floral trait evolution.
• Sexual selection may occur if pollinator attraction enhances mating success and reproductive output.

Purpose of the Study:

• To investigate sex-specific selection patterns in the insect-pollinated plant Silene dioica.
• To determine the roles of natural and sexual selection on floral traits.
• To assess the influence of pollinator-mediated selection versus direct sexual selection.

Main Methods:

• Measured floral traits and estimated individual fitness in a experimental population of Silene dioica.
• Applied Bateman's principles to quantify sexual selection.
• Compared selection strengths in open-pollinated versus hand-pollinated individuals.

Main Results:

• In females, natural selection favored fertility traits (flower number, gamete number), with similar selection under open and hand pollination, indicating limited pollinator influence.
• In males, flowering duration and corolla width correlated positively with reproductive success and mating partners, suggesting significant sexual selection.
• Bateman's metrics confirmed stronger sexual selection in males than in females.

Conclusions:

• Silene dioica exhibits sex-specific selection patterns, with sexual selection playing a more prominent role in males.
• Direct sexual selection, rather than pollinator-mediated selection, appears to be a key driver for certain floral traits in males.
• Understanding these sex-specific dynamics is crucial for comprehending plant mating system evolution.