Global distribution patterns of style-length polymorphisms
ID: 613 / 469
Proposed Symposium Title: Global distribution patterns of style-length polymorphisms
Letícia R. Novaes 1, Rafael Molina-Venegas 2, Violeta I. Simón-Porcar 1, Juan Arroyo 1
Affiliations: 1 Universidad de Sevilla, Sevilla, Spain. firstname.lastname@example.org 2 Universidad Autónoma de Madrid, Madrid, Spain.
Style-length polymorphisms consist of two or three floral morphs within a population, with a reciprocal arrangement of stigma and anther heights, which enforces outcrossing in plants by contacting different parts of the pollinator’s body with flower sex organs while avoiding self-fertilization. Other plant breeding systems, such as dioecy or self-incompatibility have been traditionally associated with tropical environments, biodiversity hotspots and oceanic islands. Tropical regions and biodiversity hotspots are known for their higher diversity of pollinators and plants, more complex pollination networks, and a higher level of specialization. Oceanic islands may, on the one hand, hamper colonization by self-incompatible species due to their inability to reproduce without pollination agents (Baker´s law) but, on the other hand, they host a significantly high occurrence of dioecy. Most of style-polymorphic plants are self-incompatible. In this study, we aim to unravel the distribution patterns of style-length polymorphism, which are still poorly understood. We investigated the historical and biogeographical determinants of the occurrence of style-length polymorphisms across all angiosperm genera at a global scale. Specifically, we tested for style-length polymorphism: (i) the existence of phylogenetic signal, (ii) the lower or higher occurrence in oceanic islands, and (iii) the higher frequency in tropical regions and biodiversity hotspots. Our results suggest that the occurrence of style-length polymorphism is significantly conserved in the angiosperm phylogeny. We also found a significantly higher presence in oceanic islands (similarly to dioecious plants), but its occurrence was not associated to tropicality or biodiversity hotspots. Style-length polymorphism showed a strong phylogenetic signal even when excluding the genera of the highly represented family Rubiaceae from the analyses. The parallel high occurrence of diecy and style-length polymorphism in oceanic islands supports the hypothesis of the evolutionary transition from style-length polymorphism towards dioecy in these habitats.