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

SILVA, GISELLA CAROLINA; SOLIS NEFFA, VIVIANA GRISELDA; KOVALSKY, IVANA EVELIN; ALMIRON, NOELIA EMILIA ALEJANDRINA

Foz do Iguaçu

Congreso; International Congress of Genetics; 2018

Sociedad brasilera de Genética

Turnera comprises 141 species classified in 11 series, distributed from the south of the UnitedStates to central Argentina, and two African species. Based on biogeographical and phylogeneticanalysis, it has been hypothesized that the greatest diversification of the genus would haveoccurred in the Chaco region, with various vicarious and dispersion events towards otherNeotropical regions and Africa. Additionally, cytogenetic studies evidenced that polyploidy is avery frequent phenomenon in Turnera. Here we combine cytogeographical analysis with nichemodelling to investigate the role of polyploidy in the diversification and distribution of Turnera inSouth 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 (currentand Last Glacial Maximum) and biogeography. Most populations were constituted by a singlecytotype, although mixed populations were also detected. The species with diploid andautopolyploid cytotypes differed each other in their cytotypes frequencies. Moreover, diploids andautopolyploids 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 theseresults evidenced that the Andean region and the Caatingas would have been centers of Turneradiversification at the diploid level, while polyploidy would have played an important role in thedispersion towards other Neotropical regions.