The eco‐evolutionary dynamics of prior selfing rates promote coexistence without niche partitioning under conditions of reproductive interference

1. Pollinator-mediated reproductive interference can occur when two or more plant species share the same pollinators. Recent studies have suggested that prior autonomous selfing mitigates reproductive interference, potentially facilitating coexistence even in the absence of pollination niche partitioning (i.e. the pre-emptive selfing hypothesis). However, whether the evolution of prior selfing promotes coexistence, in the context of the eco-evolutionary dynamics of population size, selfing rates and inbreeding depression, remains poorly understood.
2. We constructed an individual-based model to examine the conditions under which the evolution of prior selfing promotes coexistence in the context of mutual reproductive interference. In the model, two plant species compete by way of mutual reproductive interference, and both have the potential to evolve the capacity for prior autonomous selfing. We expected that purging of deleterious mutations might result in evolutionary rescue, assuming that the strength of inbreeding depression declines as the population selfing rate increases; this would enable inferior competitors to maintain population density through the evolution of prior selfing.
3. Our simulation demonstrated that evolution of prior selfing may promote coexistence, whereas reproductive interference in the absence of such evolution results in competitive exclusion. We found that lower pollinator availability is likely to favour rapid evolutionary shifts to higher prior selfing rates, thereby neutralising the negative effects of reproductive interference in both species. When the strength of inbreeding depression decreased with an increase in the population-level selfing rate, moderate pollinator availability resulted in long-term coexistence in which relative abundance-dependent selection on the prior selfing rate served to intermittently maintain the population density of the inferior competitor.
4. Synthesis. We demonstrate that the evolution of prior selfing may increase population growth rates of inferior competitors and may consequently promote long-term coexistence via an evolutionary rescue. This constitutes a novel mechanism explaining the co-evolutionary coexistence of closely related plant species without niche partitioning, and is consistent with recent studies reporting that closely related species with mixed mating systems can co-occur sympatrically, even under conditions of mutual reproductive interference.

This is the peer reviewed version of the following article: [Katsuhara, K. R., Tachiki, Y., Iritani, R., & Ushimaru, A. (2021). The eco-evolutionary dynamics of prior selfing rates promote coexistence without niche partitioning under conditions of reproductive interference. Journal of Ecology, 00, 1–13], which has been published in final form at [https://doi.org/10.1111/1365-2745.13768]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-ArchivedVersions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wileyor by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked toWiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof bythird parties from platforms, services and websites other than Wiley Online Library must be prohibited.
This fulltext is available in Sep. 2022.