Coflowering Community Context Influences Female Fitness and Alters the Adaptive Value of Flower Longevity inMimulus guttatus

Abstract

A major goal in evolutionary biology is to incorporate the complexity of multispecies interactions into our understanding of microevolutionary processes within populations. Although considerable work has been done on antagonistic interactions (e.g., plant-herbivore), little attention has been paid to the evolutionary implications of context dependency in mutualistic interactions (e.g., plant-pollinator). In this study, we use seep communities to evaluate how coflowering species richness affects key aspects of pollination (visitation rate and conspecific and heterospecific pollen receipt) of Mimulus guttatus. We assessed the importance of coflowering diversity in mediating floral evolution by determining whether species richness was associated with variation in flower size, longevity, and stigma-anther distance and by conducting a reciprocal transplant experiment in two contrasting pollination environments. We found lower visitation rates and higher heterospecific pollen transfer to M. guttatus growing in high-diversity coflowering communities compared to low-diversity coflowering communities. We found a positive correlation between flower longevity and coflowering species richness. Furthermore, our reciprocal transplant experiment showed that extended flower longevity was advantageous only in high-diversity seeps and identified coflowering diversity as the most likely selective agent. Our results suggest that coflowering diversity can promote floral trait differentiation among populations, in this case, flower longevity.

Plastic Responses Contribute to Explaining Altitudinal and Temporal Variation in Potential Flower Longevity in High Andean Rhodolirion montanum

“…Data available for Yr 2 on our sites showed that soil volumetric water content descended from 38.8% on HIGH to 5.0% on LOW (S2 Table). Lower water availability and higher temperatures at lower elevations would increase floral physiological costs, which is turn would diminish the chances of increasing reproductive success due to resource limitation for producing seeds and fruits [23]. Indeed, the capacity for rapid plastic adjustment of flower longevity under drought might have been selected in R .…”

“…Flowers that have the capacity to stay open for long periods of time in general allow more time for pollinator visits to accumulate [20,21] and thus can increase the probability of successful pollination when pollinator availability reaches a critical threshold. Nevertheless, physiological costs associated with transpiration, respiration and nectar production in flowers can drain resources for later fruit and seed set [22,23] and thus place limits on flower longevity, such that pollinator availability in natural populations is not the only factor molding flower longevity.…”

“…One such trait is potential flower longevity, the time a flower is able to remain open be and available to be pollinated. This trait has been shown to be associated with low visitation rates due to high co-flowering diversity [23] and therefore could also be associated with low visitation rates at higher altitudes. Flower longevity has been shown to increase with altitude; however the great majority of studies that show an altitudinal increase in flower longevity in the alpine (see [12]) have relied on measurements of flower longevity in open-pollinated flowers.…”

Heterospecific pollen receipt affects self pollen more than outcross pollen: implications for mixed‐mating plants

“…Plant material.-We planted 30 M. guttatus seeds each from a different maternal plant from population 1 (in Arceo-Go´mez and Ashman [2014]) at the McLaughlin Natural Reserve in northern California. Twentyeight of these plants were designated pollen recipients and functioned as self pollen donors, and the remaining two functioned as outcross pollen donors.…”

“…When HP treatment had an overall significant effect we conducted preplanned linear contrasts (Rosenthal andRosnow 1985, Abelson andPrentice 1997) to test specific hypotheses regarding the presence and arrival time of HP receipt (e.g., Strauss and Murch 2004, Arceo-Go´mez and Ashman 2011, 2014. We accounted for variation among recipients by including plant as a random factor in the models but did not test its significance.…”