THE RELATIONSHIP BETWEEN MATING-SYSTEM CHARACTERS AND INBREEDING DEPRESSION IN MIMULUS GUTTATUS

Area of Science:

• Evolutionary Biology
• Plant Reproductive Biology

Background:

• Theoretical models predict covariation between inbreeding depression and mating system traits within populations.
• The genetic basis of inbreeding depression (deleterious recessives vs. overdominance) influences expected associations.

Purpose of the Study:

• To test predictions of mating-system evolution theory in Mimulus guttatus.
• To investigate the relationship between inbreeding depression and genetic variation in herkogamy and autogamy.

Main Methods:

• Compared families from two M. guttatus populations differing in stigma-anther separation (herkogamy).
• Assessed inbreeding depression for aboveground biomass and flower production.
• Examined families differing in autogamous seed set in controlled greenhouse conditions.

Main Results:

• Significant variation in inbreeding depression among families was observed.
• Inbreeding depression levels were not explained by herkogamy or autogamy class.
• Significant dam × sire interactions indicated potential biparental inbreeding or combining ability differences.

Conclusions:

• Observed results do not support theoretical predictions of a direct link between selfing traits and reduced inbreeding depression in M. guttatus.
• Factors influencing the lack of association and variation in inbreeding depression are discussed.
• Further research is needed to understand the complex interplay of mating systems and inbreeding depression in natural populations.