Effects of pollination and postpollination processes on selfing rate in Mimulus ringens

Area of Science:

• Plant reproductive biology
• Population genetics
• Evolutionary ecology

Background:

• Selfing rates in self-compatible plants are highly variable.
• This variation is often linked to pollen deposition patterns and postpollination fertilization.
• Understanding these factors is crucial for plant breeding and conservation.

Purpose of the Study:

• To investigate the roles of pollination timing and postpollination sorting in determining selfing rates.
• To analyze the relative importance of these processes in the monkeyflower, Mimulus ringens.

Main Methods:

• Hand-pollination experiments with controlled pollen deposition timing (simultaneous, self-first, outcross-first).
• Three experimental treatments mimicked field pollination conditions.
• Progeny genotyping using 8 polymorphic microsatellite loci to determine parentage (selfed vs. outcrossed).

Main Results:

• Simultaneous and self-pollen-first treatments resulted in expected 1:1 selfed:outcrossed progeny ratios.
• Outcross-pollen-first treatment (15 min prior) yielded a significant excess of outcrossed progeny.
• Observed selfing rates were not affected by nonrandom postpollination sorting.

Conclusions:

• Selfing rates in Mimulus ringens are sensitive to the precise timing of pollen arrival.
• Small temporal differences in pollination events, not postpollination mechanisms, primarily influence selfing outcomes.
• This highlights the critical role of pollination dynamics in plant mating systems.