Geographic variation in reproductive assurance of Clarkia pulchella
Climate can affect plant populations through direct effects on physiology and fitness, and through indirect effects on their relationships with pollinating mutualists. We therefore expect that geographic variation in climate might lead to variation in plant mating systems. Biogeographic processes, such as range expansion, can also contribute to geographic patterns in mating system traits. We manipulated pollinator access to plants in eight sites spanning the geographic range of Clarkia pulchella to investigate geographic and climatic drivers of fruit production and seed set in the absence of pollinators (reproductive assurance). We examined how reproductive assurance and fruit production varied with the position of sites within the range of the species and with temperature and precipitation. We found that reproductive assurance in C. pulchella was greatest in populations in the northern part of the species’ range and was not well explained by any of the climate variables that we considered. In the absence of pollinators, some populations of C. pulchella have the capacity to increase fruit production, perhaps through resource reallocation, but this response is climate dependent. Pollinators are important for reproduction in this species, and recruitment is sensitive to seed input. The degree of autonomous self-pollination that is possible in populations of this mixed-mating species may be shaped by historic biogeographic processes or variation in plant and pollinator community composition rather than variation in climate.
KeywordsClarkia Geographic variation Pollinator exclusion Range limits Self-pollination
We would like to thank B. Harrower, R. Germain, and members of the Angert lab for their thoughtful comments on this project. We also greatly appreciate helpful comments from two anonymous reviewers. E. Fitz assisted with fieldwork. Permission to work in our field sites was granted by British Columbia Parks, Umatilla National Forest, Ochoco National Forest, and the Vale District Bureau of Land Management. MB was supported by a University of British Columbia Four-year Fellowship, and this work was also supported by a Natural Sciences and Engineering Research Council of Canada Discovery Grant to ALA.
Author contribution statement
MB and ALA designed the experiment. MB conducted field work and data collection. MB and CDM performed statistical analyses. MB drafted the manuscript in consultation with ALA, with feedback and assistance from CDM. All authors contributed to manuscript drafts and approved the final version of the manuscript.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
Data and code are available on Github at https://github.com/meganbontrager/clarkia-reproductive-assurance. Data and code are archived on Zenodo ( https://doi.org/10.5281/zenodo.2597693).
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