Search for: All records

Abstract Based on previously published molecular (mitochondrial) and herein provided morphological (qualitative and quantitative data) evidence, we describe a new species of leaf-eared mouse of the genus Phyllotis . The new species is morphometrically distinct when compared with other phylogenetically or geographically close species of Phyllotis , showing several quantitative differences in their external and craniodental characters (e.g., proportionally broader nasals and interorbital region, and proportionally smaller tympanic bullae). The new species is endemic to central Argentina, occurring on rocky grasslands at elevations of 650–2,800 m a.s.l. This is the only species of Phyllotis inhabiting the Central Sierras, a mountain system of medium elevation, isolated from the Andes by low elevation arid and semiarid environments. 

Biologists have long pondered the extreme limits of life on Earth, including the maximum elevation at which species can live and reproduce. Here we review evidence of a self-sustaining population of mice at an elevation that exceeds that of all previously reported for mammals. Five expeditions over 10 years to Volcán Llullaillaco on the Argentina/Chile border observed and collected mice at elevations ranging from 5,070 m at the mountain’s base to the summit at 6,739 m (22,110 feet). Previously unreported evidence includes observations and photographs of live animals and mummified remains, environmental DNA, and a soil microbial community reflecting animal activity that are evaluated in combination with previously reported video recordings and capture of live mice. All of the evidence identifies the mouse as the leaf-eared mouse Phyllotis vaccarum, and it robustly places the population within a haplotype group containing individuals from the Chilean Atacama Desert and nearby regions of Argentina. A critical review of the literature affirms that this population is not only an elevational record for mammals but for all terrestrial vertebrates to date, and we further find that many extreme elevations previously reported for mammals are based on scant or dubious evidence.

 

Rodents are the largest order of mammals and contain several model organisms important to scientific research in a variety of fields, yet no large set of genomic markers have been designed for this group to date, hindering evolutionary studies into relationships of the group as a whole. Here we present a genomic probe set designed and optimized for rodents with a protocol that is easy to replicate with little laboratory investment. This design utilizes an anchored hybrid enrichment approach specifically targeting rodents to generate longer loci with a higher substitution rate than existing vertebrate probes to provide utility at various taxonomic levels. Using a test set of rodents from all five suborders, we successfully obtained alignments for 416 of the 418 target loci with an average of 1379 bp per locus and a total alignment of more than half a million base pairs. This genomic data set performed well in all phylogenetic analyses, especially in recent phylogenetic splits, with ample parsimony‐informative sites within genera and even within species, showing more than four times as many single nucleotide polymorphisms per locus than a recent vertebrate ultraconserved elements study. Additional support is provided in resolving deeper clades in Rodentia. By providing this probe design, we hope that more laboratories can easily generate data for answering questions in rodents from species delimitation to understanding relationships among families in rapid radiations.

 

Environmental limits of animal life are invariably revised when the animals themselves are investigated in their natural habitats. Here we report results of a scientific mountaineering expedition to survey the high-altitude rodent fauna of Volcán Llullaillaco in the Puna de Atacama of northern Chile, an effort motivated by video documentation of mice (genus Phyllotis ) at a record altitude of 6,205 m. Among numerous trapping records at altitudes of >5,000 m, we captured a specimen of the yellow-rumped leaf-eared mouse ( Phyllotis xanthopygus rupestris ) on the very summit of Llullaillaco at 6,739 m. This summit specimen represents an altitudinal world record for mammals, far surpassing all specimen-based records from the Himalayas and other mountain ranges. This discovery suggests that we may have generally underestimated the altitudinal range limits and physiological tolerances of small mammals simply because the world’s high summits remain relatively unexplored by biologists. 

PhyllotisWaterhouse 1837 is one of the most studied genera of South American cricetid rodents. As currently understood, it includes 20 small to medium‐sized species of predominantly rocky habitats. Among them, populations of the yellow‐rumped leaf‐eared mouse, traditionally referred toP. xanthopygus(Waterhouse 1837), are the most widely distributed, extending from central Peru to southern Chile and Argentina. Based mostly on molecular evidence, previous studies suggested thatP. xanthopygusconstitutes a species complex, being characterized by geographically structured and genetically divergent clades. In this work, we compare the molecular phylogenetic hypothesis for populations distributed on the eastern slopes of the central Andes with morphometric evidence using univariate and multivariate analyses. Quantitative morphological and molecular evidence suggests that at least four nearly cryptic species of theP. xanthopyguscomplex occur from southern Bolivia to west‐central Argentina. Three of these taxa have available names; one of them,P. caprinus, is currently recognized to the species level; the other two, the clades ofP. x. posticalis‐P. x. rupestrisandP. vaccarum, are both recognized as subspecies ofP. xanthopygus. The remaining taxon represents a new species distributed in the west‐central Andes of Argentina. We discuss our morphological results in the light of other sources of evidence (e.g. qualitative and quantitative state characters, genetic and phylogenetic studies, and cytogenetic data) and name the new species asP. pehuenche, honouring the original native people that historically inhabited west‐central Andes of Argentina.