Flower color polymorphism maintained by overdominant selection in Sisyrinchium sp

Area of Science:

• Evolutionary biology
• Population genetics
• Plant sciences

Background:

• Negative frequency-dependent selection is a known mechanism for maintaining genetic diversity.
• Positive frequency-dependent foraging by pollinators can lead to loss of low-frequency morphs and monomorphism in plants.

Purpose of the Study:

• To investigate the role of overdominant selection in maintaining flower color polymorphism in Sisyrinchium sp.
• To quantify genotype-specific reproductive success in relation to flower color morphs.

Main Methods:

• Conducted artificial pollination experiments with identified genotypes of Sisyrinchium sp.
• Quantified female reproductive success for different genotypes (purple, white, heterozygotes).
• Compared observed morph frequencies in natural populations with predicted frequencies under overdominant selection.

Main Results:

• Female reproductive success was significantly higher in heterozygotes compared to homozygotes.
• Observed frequency of purple morphs (approx. 31%) aligns with predictions from overdominant selection (approx. 25%).

Conclusions:

• Overdominant selection is a key factor contributing to the maintenance of flower color polymorphism in Sisyrinchium sp.
• This study provides evidence for heterozygote advantage in reproductive success driving genetic diversity in this species.