So Far Away, Yet So Close: Strong Genetic Structure in Homonota uruguayensis (Squamata, Phyllodactylidae), a Species with Restricted Geographic Distribution in the Brazilian and Uruguayan Pampas

Abstract

The Pampas is a biologically rich South American biome, but is poorly represented in phylogeographic studies. While the Pleistocene glacial cycles may have affected the evolutionary history of species distributed in forested biomes, little is known about their effects on the habitats that remained stable through glacial cycles. The South American Pampas have been covered by grasslands during both glacial and interglacial periods and therefore represent an interesting system to test whether the genetic structure in such environments is less pronounced. In this study, we sampled Pampean populations of Homonota uruguayensis from Southern Brazil and Uruguay to assess the tempo and mode of population divergence, using both morphological measurements and molecular markers. Our results indicate that, in spite of its narrow geographic distribution, populations of H. uruguayensis show high levels of genetic structure. We found four major well-supported mtDNA clades with strong geographic associations. Estimates of their divergence times fell between 3.16 and 1.82 million years before the present. Populations from the central portion of the species distribution, on the border between Uruguay and Brazil, have high genetic diversity and may have undergone a population expansion approximately 250,000 years before the present. The high degree of genetic structure is reflected in the analyses of morphological characters, and most individuals could be correctly assigned to their parental population based on morphology alone. Finally, we discuss the biogeographic and conservation implications of these findings.

Population genomics indicates micro‐refuges and riverine barriers for a southern South American grassland nightshade

“…The geographical distribution of the lineages revealed that the river dynamics during the Pleistocene could have influenced the genetic diversity in this taxon, as described to other species from the Pampa (e.g. Felappi et al, 2015;Peçanha et al, 2017;Roratto et al, 2015;) and Chaco (e.g. Arzamendia & Giraudo, 2009;Brusquetti et al, 2018Brusquetti et al, , 2019Kopuchian et al, 2020).…”

“…Aoki‐Gonçalves et al, 2020; Fregonezi et al, 2013; Longo et al, 2014; Mäder et al, 2013; Moreno et al, 2018; Silva‐Arias et al, 2017; Turchetto et al, 2014), as well as animal species (e.g. Felappi et al, 2015; Kopuchian et al, 2020; Langone et al, 2016; Ojeda, 2010; Roratto et al, 2015; Werneck, 2011).…”

Population Genetic Structure of Cnesterodon decemmaculatus (Poeciliidae): A Freshwater Look at the Pampa Biome in Southern South America

“…Indeed, many proposals for small biological “provinces” have been made, especially regarding on the different plant communities ( Cabrera and Willink, 1980 ; Overbeck et al, 2007 ), which reflects the mosaic of soil types resulted from its complex geological history. At a smaller scale, such heterogeneity leads to high species endemism and significant genetic structure in Pampean species studied so far (e.g., Freitas et al, 2012 ; Turchetto et al, 2014 ; Felappi et al, 2015 ). While some phylogeographic studies in the Pampas have found little geographic structure and shallow gene trees [<0.1 million years ago (mya)] ( Speranza et al, 2007 ; Turchetto et al, 2014 ), other studies found strong geographic structure and a deep mitochondrial gene tree (>2.5 mya) ( Felappi et al, 2015 ).…”

“…At a smaller scale, such heterogeneity leads to high species endemism and significant genetic structure in Pampean species studied so far (e.g., Freitas et al, 2012 ; Turchetto et al, 2014 ; Felappi et al, 2015 ). While some phylogeographic studies in the Pampas have found little geographic structure and shallow gene trees [<0.1 million years ago (mya)] ( Speranza et al, 2007 ; Turchetto et al, 2014 ), other studies found strong geographic structure and a deep mitochondrial gene tree (>2.5 mya) ( Felappi et al, 2015 ). However, these studies did not include freshwater organisms, and, therefore, it is difficult to predict the level and depth of the genetic structure exhibited by these species.…”

The lizard that never sleeps: activity of the pampa marked gecko Homonota uruguayensis

“…It is a small lizard, with mean snout-vent length (SVL) of 40 mm, restricted to sandstone-basaltic rocky outcrops of the campanha region (Vaz-Ferreira & Sierra de Soriano, 1973). The high habitat specificity and strong philopatry might be the main reasons for the reduced gene flow and strong genetic structure found among H. uruguayensis populations (Felappi et al, 2015). Due to the reduced occurrence area and connectivity between populations, the species is classified as vulnerable in the Brazilian list of threatened species (MMA, 2014).…”