Chloroplast DNA variation in the Turnera sidoides L. complex (Turneraceae): biogeographical implications

Abstract

Geological processes coupled with Quaternary climatic episodes are considered by many to have played a major role in shaping current plant distributions and evolution. A great amount is known about the biogeographical effects and stimulus for speciation and intraspecific differentiation of Quaternary climatic changes in the temperate regions of the ABSTRACT Aim To analyse the current geographical structure of chloroplast DNA variation in the Turnera sidoides L. complex in order to establish historical biogeographical hypotheses for the mid-latitude South American lowlands. During the Quaternary, the climate shifted from tropical humid to cold dry, and the vegetation cover has not been stable. The consequences of these processes on the current distribution of the vegetation of this area have received very little attention.Location The mid-latitude South American lowlands extend between c. 20 and 40°S and include Uruguay, northern, central and eastern Argentina, southern Brazil, and parts of southern Paraguay and Bolivia. They are surrounded by higher-elevation systems.Methods Turnera sidoides is a well-studied polyploid complex of perennial rhizomatous herbs occurring throughout the area of interest. We analysed 321 individuals from 79 populations of the five recognized subspecies. We also included progenies from artificial crosses in order to analyse chloroplast inheritance. After screening sequences for four non-coding chloroplast DNA regions, the trnL-trnF spacer was selected to characterize the collection.Results Three haplotypes can be easily identified, with each differing from the others in two independent characters. A clear geographic structure is revealed when haplotypes are plotted for the complex as a whole regardless of subspecies and cytotype. Three distinct regions can be identified. Main conclusionsWe propose three putative refugial areas for the Turnera sidoides complex, which are associated with the orographical systems of the region. Ravines and slopes in the Haedo Cuchilla system in northern Uruguay, the elevations of the western side of the area in Argentina, and the eastern Serranías system in south-eastern Uruguay may each have served as refugia in which the A, B and C haplotypes became fixed during the drier climatic phases. Biogeographical patterns in the area covered by T. sidoides, particularly east of the Uruguay River, have not previously been analysed from a historical perspective.

Genetic diversity of wild germplasm of “yerba mate” (Ilex paraguariensis St. Hil.) from Uruguay

“…The northern germplasm (Tacuarembó) is situated in the first area mentioned in the precedents studies, whilst the mid-eastern (Treinta y Tres) and southern germplasms (Lavalleja and Maldonado) are located in the second region. The present work contributes to the knowledge of the genetic diversity of plant species from Uruguay, that so far have been focused on species of Bromus, Paspalum, Stipa, Turnera and on the Petunia axillaris complex (Rivas 2001;Speranza 2005;Speranza et al 2007;Vidal et al 2011;Turchetto et al 2014). …”

Out of the forest: past and present range expansion of a parthenogenetic weevil pest, or how to colonize the world successfully

“…The climatic changes in southern South America during this period are mostly explained by minor shifts in the location of the Pacific and Atlantic anticyclones (Antón and Goso ; Speranza et al. ). Several authors (e.g., Popolizio ; Antón and Goso ; Iriondo ; Zucol et al.…”

Range-wide patterns of nuclear and chloroplast DNA diversity in Vriesea gigantea (Bromeliaceae), a neotropical forest species

“…Despite an increasing interest in the evolutionary genetics of plant diversification in the neotropics (Rull, 2006;Barbará et al, 2008;Widmer et al, 2009), surprisingly little background information is available on the phylogeographic structure and patterns of gene flow across species' ranges in these ecosystems, compared with the temperate regions of the world (Hewitt, 2004). Biogeographic studies of taxa from the Amazon (Aleixo, 2004), the Andes (Pennington et al, 2002;Speranza et al, 2007) and the Brazilian Atlantic Rainforest (da Silva et al, 2004;Carnaval and Moritz, 2008) indicate the evolutionary complexity of the Quaternary history of South America, with a prominent role of range contractions and expansions due to the climatic changes of the Pleistocene.…”