New species of Ctenomys Blainville 1826 : (Rodentia : Ctenomyidae) from the lowlands and central valleys of Bolivia

Gardner, Scott Lyell; Salazar‐Bravo, Jorge; Cook, Joseph A.

doi:10.5962/bhl.title.142814

Cited by 31 publications

(54 citation statements)

References 26 publications

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“…We recovered phylogenetic relationships among Octodontoidea families congruent with previously published phylogenies (Upham andPatterson, 2012, 2015), as well as among Octodontidae and Octodontinae representatives (Honeycutt et al, 2003;Opazo, 2005;Upham andPatterson, 2012, 2015;Suárez-Villota et al, 2016) (Supplementary Figure S1). Within Ctenomys, we recovered the main 8 groups published by Parada et al (2011) plus some well supported intergroup relationships ( Figure 2): 1) the torquatus group being sister to the (mendocinus, talarum) group; 2) the boliviensis group is sister to the also Bolivian taxa, (C. steinbachi, (C. andersoni, C. yatesi, C. erikacuellarae)) (Gardner et al, 2014). With low posterior support (0.66) C. sociabilis results sister to C. tuconax and together with the frater group are basal to the rest of the genus.…”

Section: Multi-calibrated Timetreementioning

confidence: 78%

Spatial and temporal divergence of the torquatus species group of the subterranean rodent Ctenomys

Caraballo

Rossi

2018

CTOZ

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Subterranean rodents of the genus Ctenomys have experienced an explosive radiation and rapidly colonized the southern cone of South America. The torquatus group, one of the main groups of the genus, comprises several species and species complexes which inhabit the eastern part of the distribution of Ctenomys including southern Brazil, northern and central Uruguay and north-eastern Argentina. This group has undergone a high chromosomal diversification with diploid numbers varying from 41 to 70. The aim of this study was to investigate the origins of the torquatus group as well as its diversification patterns in relation to geography and cladogenesis. Based on mitochondrial cytochrome b nucleotide sequences we conducted a Bayesian multi-calibrated relaxed clock analysis to estimate the ages of the torquatus group and its main lineages. Using the estimated evolutionary rate we performed a continuous phylogeographic analysis, using a relaxed random walk model to reconstruct the geographic diffusion of the torquatus group in a temporal frame. The torquatus group originated during the early Pleistocene between 1.25 and 2.32 million years from the present in a region that includes the northwest of Uruguay and the southeast of the Brazilian state of Río Grande do Sul. Most lineages have dispersed early towards their present distribution areas going through subsequent range expansions in the last 800,000 -700,000 years. Ctenomys torquatus went through a rapid range expansion for the last 200,000 years, becoming the most widespread species of the group. The colonization of the Corrientes and Entre Ríos Argentinean provinces supposes at least two crossing events across the Uruguay River between 1.0 and 0.5 million years before the present, in the context of a cold and dry paleoenvironment. The resulting temporal and geographic frame enables the comprehension of the incidence of both, the amplitude of distribution areas and divergence times into the patterns of chromosomal diversification found in the group.

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Section: Multi-calibrated Timetreementioning

confidence: 78%

Spatial and temporal divergence of the torquatus species group of the subterranean rodent Ctenomys

Caraballo

Rossi

2018

CTOZ

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“…Within this assemblage of subterranean mammals, the genus Ctenomys shows the most extensive and recent radiation. Tucotucos include 68 named species and several innominate forms most of which occur in Argentina (Giménez et al, 2002;Bidau, 2006Bidau, , 2014Mirol et al, 2010;Gardner et al, 2014). SSD is usually malebiased in this genus which is expected because of the polygnic mating system of its species (Bidau and Medina, 2013).…”

Section: Introductionmentioning

confidence: 99%

A re-assessment of Rensch's rule in tuco-tucos (Rodentia: Ctenomyidae: Ctenomys) using a phylogenetic approach

Martínez

Bidau

2016

Mammalian Biology

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Keywords:Body mass Model II regression Phylogenetic reduced major axis Scaling Sexual size dimorphism a b s t r a c t Sexual size dimorphism (SSD) is affected by a large number of factors, mating system being one of the most relevant. Almost 70 species of subterranean rodents of the genus Ctenomys are considered highly polygynic, and polygyny jointly with absence of paternal care of the young, favours high SSD. In this respect, Rensch's rule predicts that SSD scales with body size so that when males are larger than females SSD tends to increase with body size. We studied SSD and Rensch's rule in 28 taxa of Ctenomys using a phylogenetic approach employing the method of phylogenetic reduced major axis (pRMA) to perform reduced major axis (RMA) model II regression in the form of log 10(male mass) on log 10(female mass). The RMA regression slope (ˇ) was statistically tested to accept or reject the null hypothesis that ˇpRMA = 1.0. A slope significantly >1.0 would signal concordance with Rensch's rule. Our results showed that despite a high degree of male-biased SSD as expected from polygynic species, Rensch's rule is not verified in this rodent group. The causes of the non-concordance with Rensch's rule as well as its taxonomic level of application are discussed in terms of current models of SSD.

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“…They occupy a wide range of habitat types, especially in open areas including grasslands, steppes, deserts and sand dunes (Redford & Eisenberg, ; Bidau, ). A few species occur in forest regions (Gardner et al ., ). These open environments differ widely in the hardness and compaction of the soil, as well as in the amount of resources available.…”

Section: Introductionmentioning

confidence: 97%

“…The genus Ctenomys (tuco‐tucos) is the most diverse among subterranean rodents (Lacey, Patton & Cameron, ). The approximately 70 described species (Gardner, Salazar‐Bravo & Cook, ; Bidau, ) are widely distributed across southern South America. They occupy a wide range of habitat types, especially in open areas including grasslands, steppes, deserts and sand dunes (Redford & Eisenberg, ; Bidau, ).…”

Section: Introductionmentioning

confidence: 99%

The role of soil features in shaping the bite force and related skull and mandible morphology in the subterranean rodents of genus Ctenomys (Hystricognathi: Ctenomyidae)

et al. 2016

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For rodents that live underground, digging in highly compacted soils requires a higher energy expenditure than digging in poorly compacted soils. We tested how soil hardness affects the bite force as well as the shape and size of the skulls and mandibles of tuco-tucos. Our hypothesis is that species that inhabit harder soils would show a stronger bite force, which should be reflected in the shape of the skull and mandible, while species living in softer soils should have a weaker bite force. We used 24 species of the genus Ctenomys to estimate bite force (through the incisor strength formula) and quantify the shape and size of the skull and mandible. Information on soil bulk density in the regions occupied by each species was obtained from the literature. We used a combination of geometric morphometric and comparative methods to test our hypothesis. A phylogenetic linear regression (PGLS) between bite force (N) and centroid size was used to account for the dependence of bite force on size. We employed a series of two-block partial leastsquares analyses to uncover the covariation between bite force and the shape of the skull and mandible. Finally, we ran five independent PGLS analyses to assess the influence of bulk density on bite force, skull shape and mandible shape, taking into account phylogenetic non-independence. Species with higher bite forces tend to inhabit more-compact soils. However, for most species, the relationship between bite force and soil bulk density was unclear, resulting in a low overall correlation. Nonetheless, differences in skull and mandible shapes were generally associated with bite force (r = 0.60). In denser soils, species with high and low bite forces occur, whereas in lower density soils, we found only species with weak bite forces. Differences in the excavation strategies among species may be responsible for this pattern.

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New species of Ctenomys Blainville 1826 : (Rodentia : Ctenomyidae) from the lowlands and central valleys of Bolivia

Cited by 31 publications

References 26 publications

Spatial and temporal divergence of the torquatus species group of the subterranean rodent Ctenomys

Spatial and temporal divergence of the torquatus species group of the subterranean rodent Ctenomys

A re-assessment of Rensch's rule in tuco-tucos (Rodentia: Ctenomyidae: Ctenomys) using a phylogenetic approach

The role of soil features in shaping the bite force and related skull and mandible morphology in the subterranean rodents of genus Ctenomys (Hystricognathi: Ctenomyidae)

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