First steps of new species: outbreeding depression and reproductive system in Epidendrum secundum (Orchidaceae)

Abstract

Plants have different reproductive systems, and the evolution of new species depends directly on the reproductive characteristics of a given population. Transitions between self-compatible and self-incompatible systems may be followed by the formation of reproductive barriers between populations with different reproductive systems. The emergence of reproductive barriers among populations of the same species may indicate the early stages of formation of new species. Previous results obtained for Epidendrum denticulatum (Orchidaceae) indicate the occurrence of outbreeding depression, which is a decrease in fertility in crosses between individuals from different populations. The occurrence of this phenomenon in other species may indicate its importance in the evolution of highly diversified groups, such as Epidendrum. The objective of this study is to test the hypothesis that outbreeding depression occurs among different populations of Epidendrum secundum, a widely distributed species in tropical montane regions in South America. Reproductive biology experiments will be conducted in individuals kept in greenhouse in order to characterize the breeding system, fertility and reproductive compatibility between E. secundum specimens from different populations. This project is included in a multidisciplinary context, where morphological and genetic analyzes are being conducted with the same plants, following the principles of integrative taxonomy. (AU)