High genetic differentiation among populations of the small cavy Microcavia australis occupying different habitats

Abstract

The small cavy Microcavia australis, a social and fossorial rodent, inhabits a large distribution range in South American arid zones. The species is versatile in coping with the seasonal and spatial variability typical of these environments through changes in morphology, physiology, and behavior. In order to explore whether phenotypic variations are related to the evolutionary history of the species, we analyzed the levels of genetic variability and divergence among four populations that differ in climate and habitat characteristics, two belonging to highlands and the other two from lowlands. We sequenced the mitochondrial control region and used the Inter Simple Sequence Repeats technique to study variability in the noncoding nuclear genome. Results from both genetic markers were consistent. Variability levels were high for all populations, and even higher for lowland ones. Pairwise genetic differentiation varied greatly, all comparisons being statistically significant except for the two highland populations. Seventeen haplotypes were detected which displayed three clear lineages: two corresponding to each lowland population and one to those in the highlands. Levels of genetic differentiation between population pairs varied widely. Haplotypes showed a mean sequence divergence of 1.4% between lowland populations and 0.2% between highland ones, whereas divergence was around 9% when populations from different altitudes were compared. Results from BEAST analysis support extant hypotheses suggesting that lowland forms are clearly older than the highland group. The deep genetic divergence between lineages poses the need to search for new evidence for properly defining the taxonomic status of divergent populations of M. australis.

Mitochondrial D-loop diversity of grasscutter (<i>Thryonomys swinderianus</i> Rodentia: Hystricomorpha) in Ghana

“…In this study, it is not unexpected that 26 different haplotypes were found coupled with high haplotype diversities (0.85 -0.97) across the three zones, owing to the fact that the D-loop has a high mutation rate [21]. These results are comparable to a previous report on a South American hystricomorph rodent, Microcavia australis [37] which indicated 0.70 -0.93 for haplotype diversity (h) and 0.0006 -0.0095 for nucleotide diversity (π). The results of our study are however higher than that of [38] on Laonastes aenigmamus in Laos (h = 0.79).…”

“…Also, genetic drift, dispersal pattern and vicariance events such as habitat fragmentation may all influence genetic structure and diversity of mammals. For instance [37] found highly differentiated highland and lowland populations of M. australis with almost all haplotypes being unique to populations, indicating very restricted levels of gene flow between the populations. Similar results were obtained by Ojeda [40] on another rodent, Tympanoctomys barrerae, in the same region.…”

Small mammal remains recovered from two archaeological sites in northwestern Mendoza (Late Holocene, Argentina): Taxonomic composition, taphonomic issues and paleoenvironmental implications

“…Numerous biological or ecological researches on current small mammals have been performed in this region (Gonnet and Ojeda, 1998;Rosi et al, 2000Rosi et al, , 2003Braun and Mares, 2002;Pardiñas et al, 2010;Novillo, 2011;Rodríguez, 2011;Sassi et al, 2011;Taraborelli et al, 2011;Novillo and Ojeda, 2014; among others). These contributions provide information about different species concerning their distribution, physiological and behavioral aspects, and habitat and food preferences, essential knowledge for the analysis of paleoenvironmental aspects linked to the assemblages under study.…”