SOLIS NEFFA viviana Griselda
congresos y reuniones científicas
Geographical Patterns of Morphological, Cytotype and cpDNA Haplotype Variation of Turnera sidoides L. Complex (Passifloraceae, Turneroideae): Evolutionary and Biogeographical Implications
Foz do Iguacu
Congreso; 21st International Chromosome Conference (ICC); 2016
Turnera sidoides (x = 7) is an excellent model to study the action of evolutionary processes in the Chaco Domain. This complex of perennial, rhizomatous herbs ranges across southern Bolivia, Paraguay and Brazil, Uruguay and Argentina, reaching 39°S. Five subspecies and 7 morphotypes were recognized in the complex. Additionally, it shows diploid to autooctoploid cytotypes. Here, we analyze the geographical distribution of morphological and genetic (cytotype and cpDNA haplotypes) variation to interpret the current patterns of diversification of the complex. Our survey revealed 2 main centers of species diversification. Most taxa have diploid and polyploid cytotypes. Within the taxa, both exclusive and shared cpDNA haplotypes were found in diploid and polyploid populations. The main concentration of diploids is located in thenorthwestern center. Their frequency regularly decreases along a north-south gradient up to 30°S, and from higher to lower altitudes. In the eastern center, a few isolated diploid populations of 4 different subspecies were detected. Tetraploids are by far the most widespread and occupy almost the entire species range, whereas the frequency of higher ploidy levels increases to the western and eastern species boundaries, in regions with the wettest and driest regimes, respectively. T. sidoides diversification would occur at 2.11 MYBP. The finding of the ancestral haplotype in diploids and polyploids occurring at the higher regions, together with the results of ancestral area reconstruction suggest that during Pleistocene geomorphological and climatic changes, the highlands alongthe Peripampasic arc and the adjacent lowlands represented putative centers of diversification of the complex. Our comprehensive analysis further yields evidence of the dispersal pathways of the T. sidoides taxa that led to the present species boundaries by means of polyploids. The Peripampasic arc would provide suitable conditions for diploids to survive and differentiate in allopatry and the main rivers as dispersal pathways toward the Chaco-Pampeanplain.