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

Foz do Iguaçu

Congreso; International Congress of genetics; 2018

Sociedade Brasilera de Genetica

Turnera comprises 141 species classified in 11 series, distributed from the south of theUnited States to central Argentina, and two African species. Based on biogeographical andphylogenetic analysis, it has been hypothesized that the greatest diversification of thegenus would have occurred in the Chaco region, with various vicarious and dispersionevents towards other Neotropical regions and Africa. Additionally, cytogenetic studiesevidenced that polyploidy is a very frequent phenomenon in Turnera. Here we combinecytogeographical analysis with niche modelling to investigate the role of polyploidy in thediversification and distribution of Turnera in South America. Ploidy level of 23 populationsof seven species of Leiocarpae (x= 7) and Turnera (x= 5) series was estimated by flowcytometry. From this data together with previous cytogenetic information, we thenanalyzed cytotypes distribution in relation to topography, climate (current and Last GlacialMaximum) and biogeography. Most populations were constituted by a single cytotype,although mixed populations were also detected. The species with diploid and autopolyploidcytotypes differed each other in their cytotypes frequencies. Moreover, diploids andautopolyploids have different habitat preferences. Diploids are mostly at higher altitudesand in the optimal niche of the taxa; while polyploids occupy less favorable areas atlowlands. All these results evidenced that the Andean region and the Caatingas wouldhave been centers of Turnera diversification at the diploid level, while polyploidy wouldhave played an important role in the dispersion towards other Neotropical regions.