Assortative mating by flowering time and its effect on correlated traits in variable environments

Area of Science:

• Ecology
• Evolutionary Biology
• Plant Science

Background:

• Reproductive timing (phenology) is a crucial life-history trait influencing mate availability, environmental exposure, and trait expression via genetic covariation.
• Phenological shifts due to climate change have significant implications for species' life histories and ecological interactions.

Purpose of the Study:

• To assess the standing genetic variation for flowering time in *Mimulus guttatus*.
• To investigate the covariation between flowering time and other vegetative traits.
• To understand how phenological variation and environmental factors interact to influence life-history evolution.

Main Methods:

• Field-collected *Mimulus guttatus* seeds were grown in a greenhouse to evaluate genetic variation for flowering time.
• Phenological assortative mating was used to create full-sib families.
• Offspring were grown under three photoperiod treatments simulating seasonal daylength variation.

Main Results:

• Substantial quantitative genetic variation for flowering time onset was observed.
• Flowering time covaried significantly with vegetative traits.
• Assortatively mated offspring exhibited over two hours of variation in critical photoperiod, affecting flowering probability across treatments.
• Resource allocation between flowering and vegetative growth varied with daylength, showing consistent covariation patterns.

Conclusions:

• *Mimulus guttatus* possesses significant genetic variation for flowering time, which is genetically correlated with other life-history traits.
• Environmental factors, such as photoperiod, interact with genetic variation to influence phenological responses.
• Future research on flowering time evolution must consider the joint dynamics of correlated traits and shifting seasonal selection under changing environmental conditions.