Plant reproductive strategies are not correlated with morphological or genetic diversity in specialized pollination interactions

Abstract

Bachground: One of the most common evolutionary transitions in angiosperms is the reproductive change from outcrossing to self-fertilization, which has occurred independently in many lineages. This transition has been associated with changes in floral biology, ecology and genetics, with selfing species experiencing reduced floral display and herkogamy, rapid plant growth, and increased inbreeding depression. Here, we aim to test whether self-compatibility was associated with a reduction in floral traits important to the attraction and interaction with pollinators, and a reduction in genetic diversity and inbreeding. Results: Our self-incompatibility tests indicated that 50% of the species studied here are self-incompatible. In relation to floral traits, we found that self-incompatible species do not show a reduction in the size of their floral traits, but rather we found larger corolla, elaiophore area, and herkogamy in self-compatible ones. The microsatellite analysis did not identify any significant decrease in the genetic diversity or increase in inbreeding levels in the self-compatible Calceolaria species. Conclusions: Despite our results go against our expectations, in the case of Calceolaria , their high dependence on only two genera of oil-bees put the species in a vulnerable position, probably facilitating the evolution of mechanisms of reproductive assurance in the absence of pollinators. As a result, the plants maintain their attraction traits while evolving an ability to self. In addition, we also did not detect a significant change in genetic diversity or inbreeding when different reproductive strategies are used. This suggests that selfing could be delayed, facilitating -when possible- the exchange of genes by cross-pollination first, and buffering the negative genetic effects of self-pollination.