Reproductive biology of Malpighiaceae: How much do we know?

The species of the family Malpighiaceae are mainly diversified in the Neotropical Region as a consequence of a specialized pollination system. Due to the production of floral oils as a reward to pollinators, and their interaction with Centris, Epicharis (Centridini) and Monoeca (Tapinotaspidini) oil-collecting bee species in most neotropical species, many studies were focused on this interesting mutualistic interaction. However, a few have approached the reproductive biology of these species. The aim of this study was to gather all the existing information to date on the reproductive biology, megagametophyte development and apomixis of the Malpighiaceae species and analyze it together. We found 39 studies on the reproductive biology of 66 species, of which 47% are self-compatible, 33.3% self-incompatible, 18.2% have a mixed system, showing variable behavior among populations and 1.5% agamospermic species. We also found studies/reports on apomixis for eight species (three genera), polyembryony for six species (five genera) and on the development of megagametophyte for 14 species. We showed that our knowledge about the reproductive biology of Malpighiaceae species is scarce and fragmented, obtaining data for only 70–80 species (6–7% out of the total), most of which belonged to one population and/or few analyzed individuals. Further studies about the integral reproductive biology of these species that focus on the analysis of inter-population variations of the reproductive characters should be carried out to better understand how certain reproductive traits of Malpighiaceae species might have evolved and to provide valuable information on the mechanisms of population differentiation.