Among-individual variation in flowering phenology affects flowering synchrony and mating opportunity

Premise of the study: The timing and pattern of a plant’s flowering can
have important consequences for reproductive success. Variation in
flowering phenology may influence the number of prospective mates, the
risk of mating with lower quality individuals, and the likelihood of
self-pollination. Here we use a common garden experiment to explore
within- and among-population variation in phenology. Our work provides new
insights into how flowering phenology shapes mating opportunity and
flowering synchrony in a self-compatible perennial. Methods: To quantify
variation in flowering phenology we raised progeny from nine populations
of Mimulus ringens in a common garden. For each individual, we measured
phenological traits including age at flowering onset, daily floral display
size, total flower number, and flowering synchrony with other members of
the population, and related these traits to mating opportunity. We also
tested how individual flowering schedules influence the magnitude of
synchrony. Key Results: Flowering phenology and synchrony varied
substantially within and among populations. From day to day, plants often
oscillated between large and small daily floral displays. Additionally,
flowering schedules of individual plants strongly influenced flowering
synchrony and, along with the number of flowering days, markedly affected
plants’ mating opportunity. Conclusions: Phenological traits such as
flowering synchrony can affect the quantity of mating opportunities and
may be important targets of natural selection. Our results highlight the
need for studies that quantify flowering patterns of individuals as well
as populations.