Conservatoire et Jardin botaniques de la Ville de Genève
Biogéographie et mode de spéciation des Sinningieae (Gesneriaceae)
Biogeography of Neotropical Gesneriaceae
Biogeographic inferences based on dated phylogenetic trees have provided insights into how past geological and climatic events have shaped the current biotic distribution of plants. In this project we aim to reconstruct the historical biogeography of Gesneriaceae across the Neotropics and within the Brazilian Atlantic forest, known as a hotspot of biodiversity.
Biogeographical history of Neotropical Gesneriaceae - Gesneriaceae are represented in the New World by a major clade (c. 1000 species) currently recognized as subfamily Gesnerioideae. Radiation of this group occurred in all biomes of tropical America and was accompanied by extensive phenotypic and ecological diversification. Based on phylogenetic and molecular dating analyses, we suggest that ancestors of Gesneriaceae originated in South America during the Late Cretaceous. It is only later, during the Oligocene and the early Miocene, that ancestors of Gesnerioideae expanded across the Neotropics by colonizing several regions including the tropical Andes, Brazilian Atlantic forest, cerrado, Central America and the West Indies. Subsequent diversification within these areas occurred largely in situ and was particularly extensive in the mountainous systems of the Andes, Central America and the Brazilian Atlantic forest. For example, only two radiations account for 90% of the diversity of Gesneriaceae in the Brazilian Atlantic forest, whereas half of the species richness in the northern Andes and Central America originated during the last 10 Myr from a single radiation (Perret et al. 2013).
Biogeography and speciation of Sinningieae in the Brazilian Atlantic forest - The historical biogeography of the tribe Sinningieae (Gesneriaceae) was analyzed based on distribution data and a near-complete species-level phylogenetic tree (Perret et al. 2006). This plant group is distributed from Mexico to northern Argentina, but by far the highest diversity occurs within the Brazilian Atlantic forest; an area known as a "hotspot" of biodiversity. Results indicate that the Sinningieae probably arose in the coastal rain forest or in the neighboring area delimited by the São Francisco river in Brazil. The majority of the dispersal-vicariance episodes were reconstructed between the Brazilian Atlantic rain forests and their neighboring inland areas (i.e., Paraná and São Francisco regions). In contrast, dispersal events between the tropical and subtropical portions of the Brazilian Atlantic forest were limited, indicating a north-south disjunction during Sinningieae diversification. Occurrence of Sinnningieae species in the Andes and Central America are mainly explained by recent range expansions of single species. The analyses of geographical range overlaps between sister clades showed that diversity in Sinningieae is mainly the product of allopatric speciation and that sympatries mainly result from dispersal events occurring after speciation events (Perret et al. 2007).
Perret, M., A. Chautems., A.O. Araujo, and N. Salamin. 2013. Temporal and spatial origin of Gesneriaceae in the New World inferred from plastid DNA sequences. Botanical Journal of the Linnean Society, 171, 61-79.
Perret, M., A. Chautems, R. Spichiger, T. G. Barraclough, and V. Savolainen. 2007. The geographical pattern of speciation and floral diversification in the Neotropics : the tribe Sinningieae (Gesneriaceae) as a case study. Evolution 61:1641-1660.
Perret, M., A. Chautems, and R. Spichiger. 2006. Dispersal-vicariance analyses in the tribe Sinningieae (Gesneriaceae): a clue to understanding biogeographical history of the Brazilian Atlantic forest. Annals of the Missouri Botanical Garden 93 (2): 340-358.
Dr. Nicolas Salamin (University of Lausanne)