Evolution of morphological adaptations for digging in living and extinct ctenomyid and octodontid rodents

To examine the evolution of burrowing specializations in the sister families Octodontidae and Ctenomyidae (Rodentia: Caviomorpha), we produced a synthetic phylogeny (supertree), combining both molecular and morphological phylogenies, and including both fossil and extant genera. We mapped morphological specializations of the digging apparatus onto our phylogenetic hypothesis and attempted to match morphological diversity with information on the ecology and behaviour of octodontoid taxa. Burrowing for sheltering and rearing is the rule among octodontids and ctenomyids, and adaptations for digging have been known from the Early Pliocene onward. However, only a few taxa have evolved fully subterranean habits. Scratch-digging is widespread among both semifossorial and fully subterranean lineages, and morphological changes associated with scratch-digging are not restricted to subterranean lineages. By contrast, various adaptations for chisel-tooth digging are restricted to some subterranean lineages and are combined differently in the octodontid Spalacopus, the fossil ctenomyid Eucelophorus, and some living Ctenomys. Some octodontid taxa are able to dig complex burrows in spite of having no substantial changes in musculoskeletal attributes. Hence, we suggest that, during the early evolution of those branches giving rise to fully subterranean ctenomyids and octodontids, a change in behaviour probably preceded the origin of structural adaptations.Facultad de Ciencias Naturales y Muse

Evolution of morphological adaptations for digging in living and extinct ctenomyid and octodontid rodents

To examine the evolution of burrowing specializations in the sister families Octodontidae and Ctenomyidae (Rodentia: Caviomorpha), we produced a synthetic phylogeny (supertree), combining both molecular and morphological phylogenies, and including both fossil and extant genera. We mapped morphological specializations of the digging apparatus onto our phylogenetic hypothesis and attempted to match morphological diversity with information on the ecology and behaviour of octodontoid taxa. Burrowing for sheltering and rearing is the rule among octodontids and ctenomyids, and adaptations for digging have been known from the Early Pliocene onward. However, only a few taxa have evolved fully subterranean habits. Scratch-digging is widespread among both semifossorial and fully subterranean lineages, and morphological changes associated with scratch-digging are not restricted to subterranean lineages. By contrast, various adaptations for chisel-tooth digging are restricted to some subterranean lineages and are combined differently in the octodontid Spalacopus, the fossil ctenomyid Eucelophorus, and some living Ctenomys. Some octodontid taxa are able to dig complex burrows in spite of having no substantial changes in musculoskeletal attributes. Hence, we suggest that, during the early evolution of those branches giving rise to fully subterranean ctenomyids and octodontids, a change in behaviour probably preceded the origin of structural adaptations.Facultad de Ciencias Naturales y Muse

Selective binocular vision loss in two subterranean caviomorph rodents: Spalacopus cyanus and Ctenomys talarum

To what extent can the mammalian visual system be shaped by visual behavior? Here we analyze the shape of the visual fields, the densities and distribution of cells in the retinal ganglion-cell layer and the organization of the visual projections in two species of facultative non-strictly subterranean rodents, Spalacopus cyanus and Ctenomys talarum, aiming to compare these traits with those of phylogenetically closely related species possessing contrasting diurnal/nocturnal visual habits. S. cyanus shows a definite zone of frontal binocular overlap and a corresponding area centralis, but a highly reduced amount of ipsilateral retinal projections. The situation in C. talarum is more extreme as it lacks of a fronto-ventral area of binocular superposition, has no recognizable area centralis and shows no ipsilateral retinal projections except to the suprachiasmatic nucleus. In both species, the extension of the monocular visual field and of the dorsal region of binocular overlap as well as the whole set of contralateral visual projections, appear well-developed. We conclude that these subterranean rodents exhibit, paradoxically, diurnal instead of nocturnal visual specializations, but at the same time suffer a specific regression of the anatomical substrate for stereopsis. We discuss these findings in light of the visual ecology of subterranean lifestylesFil: Vega Zuniga, Tomas. Universidad de Chile; ChileFil: Medina, Felipe. Universidad de Chile; ChileFil: Marin, Gonzalo. Universidad de Chile; ChileFil: Letelier, Juán Carlos. Universidad de Chile; ChileFil: Palacios, Adrián G.. Universidad de Valparaíso; ChileFil: Němec, Pavel. Charles University in Prague; República ChecaFil: Schleich, Cristian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Mpodozis, Jorge. Universidad de Chile; Chil

Evolution of morphological adaptations for digging in living and extinct ctenomyid and octodontid rodents

To examine the evolution of burrowing specializations in the sister families Octodontidae and Ctenomyidae (Rodentia: Caviomorpha), we produced a synthetic phylogeny (supertree), combining both molecular and morphological phylogenies, and including both fossil and extant genera. We mapped morphological specializations of the digging apparatus onto our phylogenetic hypothesis and attempted to match morphological diversity with information on the ecology and behaviour of octodontoid taxa. Burrowing for sheltering and rearing is the rule among octodontids and ctenomyids, and adaptations for digging have been known from the Early Pliocene onward. However, only a few taxa have evolved fully subterranean habits. Scratch-digging is widespread among both semifossorial and fully subterranean lineages, and morphological changes associated with scratch-digging are not restricted to subterranean lineages. By contrast, various adaptations for chisel-tooth digging are restricted to some subterranean lineages and are combined differently in the octodontid Spalacopus, the fossil ctenomyid Eucelophorus, and some living Ctenomys. Some octodontid taxa are able to dig complex burrows in spite of having no substantial changes in musculoskeletal attributes. Hence, we suggest that, during the early evolution of those branches giving rise to fully subterranean ctenomyids and octodontids, a change in behaviour probably preceded the origin of structural adaptations.Facultad de Ciencias Naturales y Muse

Daily patterns of activity in free-living Rio Negro Tuco-Tucos (Ctenomys rionegrensis)

Activity patterns are a fundamental aspect of the biology of many species, with important implications for survival and reproduction. Typically, such patterns of activity are thought to be entrained by light cues, raising intriguing questions about the nature of circadian rhythms in subterranean species, members of which spend virtually their entire lives in dark, underground burrows. As part of ongoing studies of the behavioural biology of the Rio Negro tuco-tuco (Ctenomys rionegrensis), we used data from free-living animals to characterize daily patterns of activity in this subterranean species of rodent. The locations of 5 radiocollared adults were recorded hourly for 72 consecutive hours during November, 2005. Analyses of 5 measures of activity based on these data revealed that individuals changed locations more often and moved greater distances between successive radio fixes during daylight hours. These data are consistent with studies of other ctenomyid rodents in suggesting that C. rionegrensis tends toward diurnality. Comparisons with other lineages of subterranean rodents indicate that activity patterns vary markedly among these burrow-dwelling mammals, with substantial intra- as well as inter-specific differences in activity reported

The postcranial skeleton of caviomorphs: morphological diversity, adaptations and patterns

Fil: Morgan, Cecilia Clara. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Zoología Vertebrados; Argentin

Energetics and thermal adaptation in semifossorial pine-voles Microtus lusitanicus and Microtus duodecimcostatus

Acknowledgments are due for the financial support to Centre for environment and marine studies (UID/AMB/50017-POCI-01-0145-FEDER-007638), to Fundação para a Ciência e Tecnologia through national funds (PIDDAC), and the co-funding by the FEDER, within the PT2020 Partnership Agreement and Compete 2020. RIM was supported by fellowship BPD/UI88/7346/2016 and JRS was supported by the 1000 talents program of the Chinese government. We thank the three anonymous referees for their valuable comments on this manuscript.Peer reviewedPostprin

Helminth and Protozoan Parasites of Subterranean Rodents (Chordata, Mammalia, Rodentia) of the World

Published studies and ten new unpublished records included herein reveal that approximately 174 species of endoparasites (helminths and protozoans) are known from 65 of 163 species of rodents that occupy the subterranean ecotope globally. Of those, 94 endoparasite species were originally described from these rodents. A total of 282 host-parasite associations are summarized from four major zoogeographic regions including Ethiopian, Palearctic/Oriental, Nearctic, and Neotropical. Thirty-four parasite records from the literature have been identified to only the level of the genus. In this summary, ten new records have been added, and the most current taxonomic status of each parasite species is noted. Interestingly, there are no data on endoparasites from more than 68% of described subterranean rodents, which indicates that discovery and documentation are at an early stage and must continue

Diversidad morfológica cráneo-mandibular de roedores caviomorfos en un contexto filogenético comparativo

Tesis presentada para optar al Grado de Doctor en Ciencias NaturalesFil: Alvarez, Alicia. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; Argentin