Population Rescue through an Increase in the Selfing Rate under Pollen Limitation: Plasticity versus Evolution

Area of Science:

• Ecology
• Evolutionary Biology
• Population Genetics

Background:

• Self-fertilization offers reproductive assurance against pollen limitation but can reduce fitness by exposing deleterious mutations.
• Environmental changes can trigger plastic mating system shifts toward self-pollination, with immediate benefits and costs.

Purpose of the Study:

• To explore demographic and genetic conditions for population rescue via self-fertilization (plasticity and/or evolution) following pollen limitation.
• To compare the effectiveness of plasticity versus evolution in population rescue through increased selfing.

Main Methods:

• Eco-evolutionary modeling was used to simulate population dynamics under varying levels of pollen limitation and selfing rates.
• The models assessed population rescue probability based on demographic and genetic factors.

Main Results:

• Population rescue is most likely with intermediate selfing rate increases, with higher thresholds under stronger pollen limitation.
• Rescue via plasticity is generally more probable than rescue via evolution.
• Under weak pollen limitation, purging of deleterious mutations may drive rescue more than reproductive assurance.

Conclusions:

• Plasticity plays a crucial role in plant population rescue under sudden pollen limitation.
• The optimal selfing rate increase for rescue depends on factors like pollen limitation severity and initial population size.
• Findings offer insights into the evolution of mating system plasticity and its ecological significance.