At the beginning and at the end: Combined mechanisms of prior and delayed self-pollination interact to make a 'winner' species

摘要

Reproduction is key to determine the success of "winner" species. Plants that have an autogamous reproductive system to ensure their reproduction, but which maintain the possibility of cross-pollination, are the most flexible. Here, we aimed at understanding how those mechanisms occur in Sida cordifolia, an introduced pantropical weed. We recorded self-pollination mechanisms, monitored flower anthesis, and carried out a functional morphometric analysis. Based on those data, we established an experimental design of controlled pollination to measure the reproductive success generated by each self-pollination mechanism. We found two spontaneous self-pollination mechanisms: a prior one, during pre-anthesis, and a delayed one, at the moment of flower closure. However, partial dichogamy and herkogamy maintained during anthesis enabled cross-pollination. The floral attributes that maintain these mechanisms are fixed in the population. Alone, self-pollination mechanisms provide half of the fruit production, but together they are comparable to natural and cross-pollination with nearly total success. We show, for the first time, the interaction between prior and delayed self-pollination mechanisms and discuss how their combination enables autogamy but maintains the possibility of cross-pollination. The similar floral morphology of species of the pantropical genus Sida and the diversified self-pollination mechanisms in the family Malvaceae lead us to believe that this process may occur worldwide. Weedy species can be models for studies of floral biology, as they may have unique floral mechanisms that make them "winners" in the context of biotic homogenization.