Cytogeographic analysis and bioclimatic modeling in Turnera (Passifloraceae, Turneroideae) evidence the role of polyploidy in the species dispersion towards South American Neotropical lowlands.

SILVA, M.C.; KOVALSKY, I. E.; ALMIRÓN, N.E.A.; VIVIANA GRISELDA SOLIS NEFFA

Foz do Iguacu

Congreso; International Congress of Genetics; 2018

International Genetics Federation

Turnera comprises 141 species classified in 11 series, distributed from the south of the United States to central Argentina, and two African species. Based on biogeographical and phylogenetic analysis, it has been hypothesized that the greatest diversification of the genus would have occurred in the Chaco region, with various vicarious and dispersion events towards other Neotropical regions and Africa. Additionally, cytogenetic studies evidenced that polyploidy is avery frequent phenomenon in Turnera. Here we combine cytogeographical analysis with niche modelling to investigate the role of polyploidy in the diversification and distribution of Turnera in South America. Ploidy level of 23 populations of seven species of Leiocarpae (x= 7) and Turnera (x= 5) series were estimated by flow cytometry. From this data together with previous cytogeneticinformation, we then analyzed cytotypes distribution in relation to topography, climate (current and Last Glacial Maximum) and biogeography. Most populations were constituted by a single cytotype, although mixed populations were also detected. The species with diploid and autopolyploid cytotypes differed each other in their cytotypes frequencies. Moreover, diploids and autopolyploids have different habitat preferences. Diploids are mostly at higher altitudes and inthe optimal niche of the taxa; while polyploids occupy less favorable areas at lowlands. All these results evidenced that the Andean region and the Caatingas would have been centers of Turnera diversification at the diploid level, while polyploidy would have played an important role in the dispersion towards other Neotropical regions.