Context-dependent autonomous self-fertilization yields reproductive assurance and mixed mating

Area of Science:

• Evolutionary Biology
• Plant Reproductive Ecology

Background:

• Self-fertilization (selfing) is common in plants, with significant populations exhibiting high or intermediate selfing rates.
• The evolution of selfing is often counteracted by inbreeding depression, yet its prevalence suggests adaptive benefits.
• Darwin's reproductive assurance hypothesis posits that selfing provides a reproductive benefit when outcrossing is limited.

Purpose of the Study:

• To provide empirical evidence for the reproductive assurance hypothesis under variable pollination conditions.
• To investigate the ecological and genetic factors that favor self-pollination in mixed mating systems.
• To demonstrate how variable pollination environments can lead to increased selfing rates in natural populations.

Main Methods:

• Field observations of pollinator activity and seed production in Collinsia verna.
• Measurement of inbreeding depression in experimental crosses.
• Estimation of selfing rates using genetic markers.

Main Results:

• Infrequent pollinator visits were shown to increase seed output per flower through autonomous self-pollination.
• Low inbreeding depression was observed in the study population.
• Marker-based estimates confirmed that selfing rates increase when pollination environments necessitate reproductive assurance.

Conclusions:

• This study provides a complete demonstration of reproductive assurance under variable pollination.
• The findings mechanistically link reproductive assurance to intermediate selfing rates via mixed mating.
• Variable pollination environments can create both ecological and genetic conditions favoring self-pollination in plants.