Redefining the Distributional Boundaries and Phylogenetic Relationships for Ctenomids From Central Argentina

Abstract

With about 68 recognized living species, subterranean rodents of the genus Ctenomys are found in a multiplicity of habitats, from the dunes of the Atlantic coast to the Andes Mountains, including environments ranging from humid steppes of Pampas to the dry deserts of Chaco region. However, this genus needs an exhaustive reevaluation of its systematic and phylogenetic relationships regarding the different groups that compose it. This knowledge is essential to propose biodiversity conservation strategies both at species level and at higher hierarchical levels. In order to clarify the taxonomy and the recent evolutionary history from populations of Ctenomys in the Pampas region, Argentina, phylogenetic relationships among them were evaluated using mitochondrial DNA sequences: gene encoding cytochrome b protein (1,140 bp) and the non-coding D-loop region (434 bp). To infer the divergence times inside the Ctenomys clade, a Bayesian calibrate tree using fossil remains data from different families within Caviomorpha was performed at first. Secondly, that calibration data was used as priors in a new Bayesian phylogenetic inference within the genus Ctenomys. This phylogenetic tree emphasized on species currently distributed on the Pampas region, more precisely considering both the talarum and mendocinus groups. Bayesian inferences (BI) were integrated with the results of a Maximum Likelihood approach (ML). Based on these results, the distributional limits of the mendocinus and talarum groups appear to be related to the physiognomy of the Pampas region soils. On the other hand, the validity of C. pundti complex as a differentiated species of C. talarum is debated. According to previous evidence from morphological and chromosomal studies, these results show a very low divergence between those species that originally were classified within the talarum group. Mitochondrial DNA sequences from populations associated with these putative species have not recovered as reciprocal monophyletic groups in the phylogenetic analyses. In conclusion, C. talarum and C. pundti complex might be considered as the same biological species, or lineages going through a recent or incipient differentiation process. The results obtained in this study have important implications for conservation policies and practices, since both species are currently categorized as Vulnerable and Endangered, respectively.

Genetic footprints of Quaternary climatic fluctuations on the endangered Tuco-tuco-das-dunas (Ctenomys flamarioni)

“…These results highlight the importance of such barriers (current and ancient)—along with geographic discontinuities between populations of C. flamarioni —in shaping patterns of genetic variations and gene flow, as observed for other species of the genus (see Lopes et al 2013; Mora et al 2013; Mapelli et al 2017, 2021; Tammone et al 2018; Medeiros et al 2020; Carnovale et al 2021, 2023).…”

“…Runs were performed under an uncorrelated lognormal relaxed-clock model; speciation was modeled on a Birth–Death model process with empirical base frequencies and 4 gamma rate categories. We used a normal distribution (mean and initial) for the substitution rate using the evolutionary rate estimated for Ctenomys as 2.02% per million years (Myr –1 ) for Cytb and 2.95% per million years (Myr –1 ) for D-loop (Carnovale et al 2021). In addition to the 78 sequences generated here, sequences of different species of Ctenomys (inside and outside the mendocinus group) were extracted from the GenBank database and included in the phylogenetic analyses, as well as sequences from Octodon degus and Spalacopus cyanus used as outgroups (Appendix II).…”

Cambios en Las Comunidades De Micromamíferos Durante El Holoceno Tardío–antropoceno en El Sudeste De La Provincia De Buenos Aires (Argentina)

“…La situación corológica de las poblaciones de Ctenomys talarum en lo que hace al litoral bonaerense fue expuesta por Reig (1964Reig ( , 1965Contreras y Reig, 1965) y no ha variado, en forma sustantiva, desde entonces, pese a la intensificación de las prospecciones (e.g., Mora et al, 2007Mora et al, , 2013Carnovale et al, 2021;Austrich et al, 2021). Como señalara Reig (1964) Messineo, 2016); y (3) parecen haberse retraído regional-mente de forma sincrónica.…”

A new species of the highly polytypic South American rodent Ctenomys increases the diversity of the magellanicus clade

“…In such a still largely inconclusive scenario, however, major systematic and phylogenetic knowledge has been generated in just over two decades (e.g., Lessa and Cook 1998;D'Elía et al 1999;Mascheretti et al 2000;Slamovits et al 2001;Castillo et al 2005;Parada et al 2011;Gardner et al 2014;Bidau 2015;Freitas 2016Freitas , 2021Caraballo and Rossi 2018;Fornel et al 2018;Leipnitz et al 2020;Teta and D'Elía 2020;D'Elía et al 2021;De Santi et al 2021). One of the most significant advances is the recognition of informal groups of species based on increasingly well-supported clades (Parada et al 2011;Freitas et al 2012;Gardner et al 2014;Caraballo and Rossi 2018;Londoño-Gaviria et al 2018;Leipnitz et al 2020;De Santi et al 2020, 2021Carnovale et al 2021).…”