Spiny pocket mouse ca11/1/2022 ![]() ![]() Hence, the pallid kangaroo mouse is a highly specialized, sand-obligate organism, and an understanding of its phylogeographical patterns may provide a model for future studies of other sand-obligate organisms in the Great Basin. Although M. megacephalus tolerates a variety of sandy substrates and floral associations throughout the Great Basin, M. pallidus is restricted typically to fine, loose, sandy soils (with little or no gravel overlay) in the lower portion of the Upper Sonoran Life Zone. Relative to its congener, M. pallidus has more highly inflated auditory bullae, larger hind feet, a smaller geographical distribution, and is more stenotopic ( Hall, 1941 Hafner, 1981 Hafner et al., 1996). ![]() Morphologically and ecologically, M. pallidus appears to be more specialized than M. megacephalus. Kangaroo mice are also considered to be rather uncommon members of the nocturnal desert rodent community ( Hall, 1941 Hafner, 1981 Hafner et al., 1996). ![]() Only two species are currently recognized in the genus: M. megacephalus Merriam, the dark kangaroo mouse, and M. pallidus Merriam, the pallid kangaroo mouse. Relative to other heteromyid genera, Microdipodops has an unusually small geographical distribution and is depauperate in number of species ( Schmidly et al., 1993 Patton, 2005 Hafner et al., 2007). Kangaroo mice, genus Microdipodops Merriam, belong to the rodent family Heteromyidae Gray and are restricted in distribution to sandy habitats in the Great Basin Desert of western North America. The phylogeographical patterns described here may serve as a model for other sand-obligate members of the Great Basin Desert biota. Estimated times of divergence of the principal clades of M. pallidus (4.38 Ma) and between M. pallidus and M. megacephalus (8.1 Ma data from a related study) indicate that kangaroo mice diverged much earlier than thought previously. The eastern and western clades are likely to represent morphologically cryptic species. Main conclusions The geographical range of M. pallidus seems to be remarkably stable in historical times and does not show a northward (or elevationally upward) movement trend, as has been reported for some other kinds of organism in response to global climate change. Axial data from haplotype sharing between pairwise localities show significant, non-random angular patterns: a north-west to south-east orientation in the western clade, and a north-east to south-west directional pattern in the eastern clade. Nine of the 42 unique composite haplotypes are present at two or more localities and are used for the orientation analyses. In the eastern clade, however, three subgroups are recognized. The western clade shows little phylogenetic structure and seems to represent a large polytomy. Two principal phylogroups, distributed as eastern and western moieties, are evident from the phylogenetic analyses (mean sequence divergence for cytochrome b is c. Results Collecting activities showed that M. pallidus is a rather rare rodent (mean trapping success was 2.88%), and its distribution has changed little from that determined three-quarters of a century ago. Directional analysis of phylogeographical patterns, a novel method, was used to examine angular measurements of haplotype sharing between pairs of localities to detect and quantify historical events pertaining to movement patterns and gene flow. Molecular sequence data were analysed using neighbour-joining, maximum-parsimony, maximum-likelihood and Bayesian methods of phylogenetic inference. Methods Mitochondrial DNA sequence data from portions of three genes (16S ribosomal RNA, cytochrome b, and transfer RNA for glutamic acid) were obtained from 98 individuals of M. pallidus representing 27 general localities sampled throughout its geographical range. ![]() Location The Great Basin Desert region of western North America, especially the sandy habitats of the Lahontan Trough and those in south-central Nevada. In addition, we test for orientation patterns in haplotype sharing for evidence of past episodes of movement and gene flow. Our principal intent is to identify its current geographical distribution and to formulate a phylogeographical hypothesis for this taxon. The pallid kangaroo mouse, M. pallidus, is a sand-obligate desert rodent. Aim Kangaroo mice, genus Microdipodops Merriam, are endemic to the Great Basin and include two species: M. pallidus Merriam and M. megacephalus Merriam. ![]()
0 Comments
Leave a Reply.AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |