Population and species boundaries in the South American subterranean rodent Ctenomys in a dynamic environment

Abstract

Subterranean rodents of the genus Ctenomys are an interesting system to assess the effects of habitat instability on the genetic structure of populations. The perrensi group is a complex of three species (C. roigi, C. perrensi and C. dorbignyi) and several forms of uncertain taxonomic status, distributed in the vicinity of the Iberá wetland in Argentina. Because of limited availability of suitable dry habitat, Ctenomys populations are distributed patchily around a vast mosaic of marshes, swamps and lagoons and become connected or isolated over time, depending particularly on the precipitation regime. Genetic variation at 16 microsatellite loci in 169 individuals collected in the area revealed eight clusters of populations which are thought to be evolutionary units, but which do not fit previous species limits. We interpret this lack of congruence between taxonomy and genetic structure as the result of a dynamic population structure. Where populations become connected, hybridization is possible. Where populations become isolated, rapid genetic divergence may occur. In the perrensi group, it appears that both of these factors disrupt the association between different genetic and morphological characters. The study of multiple characters is crucial to the understanding of the recent evolutionary history for dynamic systems such as this. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 368–383.

Integrative lineage delimitation in rodents of the Ctenomys Corrientes group

“…This population shows a secondary affinity to the Ctenomys perrensi complex, being basal to the clade 2 in the mtDNA phylo geny and, although it forms an exclusive SSR cluster (L), it is included into a hierarchic cluster together with San Roque, Goya and Chavarría (Table 1). In fact, when members of San Joaquín de Miraflores (Entre Ríos) are included in the analysis, Paraje Sarandicito falls into a SSR cluster with this population (Mirol et al 2010). However, as stated above, San Joaquín de Miraflores falls within a clade which also includes the C. pearsoni complex in the cyt-b based phylogeny (Figure 3) and hence belongs to a different lineage.…”

“…Karyotypical information was then published by Ortells et al (1990) who found that Mbarigüí and Paraje Sarandicito had undistinguishable 2n = 70 FN = 84 karyotypes (Table 1). Hence, these two disjunct nucleuses, although they are 350 km away, maintained their adscription to Ctenomys dorbignyi and were identified as relicts (Mirol et al 2010, Gómez Fernández et al 2012, mtDNA phylogenetic clades (Caraballo et al 2012) Argüelles et al (2001) ascribed to this species a third karyotypically related group of populations from the localities of Paso Vera and San Joaquín de Miraflores, at the Entre Ríos Province. Taking these three nucleuses into consideration C. dorbignyi was considered Near Threatened in the IUCN Red List (Bidau et al 2008b).…”

“…We consider Santa Rosa as a member of this complex, not only because it shares the same FN and is included in this group in the mtDNA phylogeny, but also because it falls into an exclusive cluster with all Ctenomys perrensi complex populations (San Roque, Chavarría and Goya) in previous SSR clusters (Mirol et al 2010). In turn, Paraje Sarandicito is not considered part of this lineage and will be discussed in the following item.…”

“…Morphological analyses (Contreras and Scolaro 1986, Contreras 1988, Ortells 1990), cytogenetic studies , García et al 2000b, Argüelles et al 2001, Caraballo et al 2015, chromosome banding (Ortells 1995), satellite DNA dynamics (Caraballo et al 2010), allozymic distances (Ortells and Barrantes 1994), population genetic studies (Mirol et al 2010, Gómez Fernández et al 2012, and mitochondrial phylogenies (Giménez et al 2002, Caraballo et al 2012) have been performed. From a morphological perspective, the populations comprising the Corrientes group, even the ones considered to belong to different nominal species showed little or no differentiation (Figure 1, Ortells 1990) and hence are likely to be cryptic ones.…”

Chromosomes and speciation in tuco-tuco (Ctenomys, Hystricognathi, Rodentia)

“…Эта классификация была основана главным образом на анализе морфологических признаков, таких как особен-ности морфологии черепа, окраски меха и размера тела. Со временем для классификации стали использовать особенности кариотипов (Reig, Kiblisky, 1969), морфо-логию сперматозоидов (Feito, Gallardo, 1982), частоты аллозимных локусов (Sage et al, 1986) и молекулярных маркеров (Lessa, Cook, 1998;Mascheretti et al, 2000;Giménez et al, 2002;Castillo et al, 2005;Mirol et al, 2010;Parada et al, 2011).…”