TESTING BIOGEOGRAPHICAL HYPOTHESES IN MID-LATITUDE SOUTH AMERICAN LOWLANDS: INFERENCES FROM PHYLOGEOGRAPHIC ANALYSIS IN TURNERA SIDOIDES.

V.G. SOLIS NEFFA

Conferencia; XVI CONGRESO LATINOAMERICANO DE GENÉTICA IV CONGRESO DE LA SOCIEDAD URUGUAYA DE GENÉTICA XLIX REUNIÓN ANUAL DE LA SOCIEDAD DE GENÉTICA DE CHILE XLV CONGRESO ARGENTINO DE GENÉTICA; 2016

Sociedad Argentina de Genética

In the subtropical and temperate South American lowlands, the numerous episodes of geomorphologic and climatic changes during the Neogene must have been critical in determining current species distribution patterns. Information available mainly from geomorphologic and stratigraphic studies indicates that the flora of this region has undergone several cyclical displacements as the drier-colder climatic conditions advanced and retreated in a SW-NE direction. In this context, a phylogeographic analysis based on cpDNA sequences was used in the Turnera sidoides autopolyploid complex (Passifloraceae, Turneroideae) to test some historical biogeographical hypothesis for this area. This complex of perennial, rhizomatous herbs has the potential to be an excellent model system since it ranges naturally over this region and its diversification was estimated at 2.11 m.y.b.p (from Pliocene onwards). The results obtained in the complex supports the interpretation that higher elevation ranges and some lowlands areas in the western limit of the Chaco plain may have served as refugia for the flora requiring moister conditions during the cold-dry phases of Neogene climatic cycles. In addition, the Peripampasic arc as well as the main rivers of the region would have served as dispersal pathways toward the Chaco-Pampean plain. However, comparisons of the phylogeographycal patterns found in T. sidoides with the floristic and genetic patterns for other species suggest the occurrence of new specific refugia and dispersion routes, providing valuable hypotheses to be addressed by future research to obtain a complete overview of the historical biogeography of mid-latitude South American lowlands.