Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Rodentia”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 433 records · Page 24Linked to original sources
PubMed2004

Molecular phylogeny and biogeography of woolly flying squirrel (Rodentia: Sciuridae), inferred from mitochondrial cytochrome b gene sequences.

To investigate the genetic diversity between the populations of woolly flying squirrels (Eupetaurus) from the eastern and western extremes of the Himalayas, partial mitochondrial cytochrome b gene sequences (390-810 bp) that were determined from the museum specimens were analyzed using maximum parsimony (MP) and maximum likelihood (ML) methods. The molecular data reveal that the two specimens that were collected in northwestern Yunnan (China) are members of the genus Eupetaurus. Reconstructed phylogenetic relationships show that the populations of Eupetaurus in the eastern and western extremes of the Himalayas are two distinct species with significant genetic differences (12%) and diverged about 10.8 million years ago. Eupetaurus is significantly different from Petaurista and Pteromys. The level of estimated pairwise-sequence divergence observed between Eupetaurus and Petaurista or Pteromys is greater than that observed between Eupetaurus and Trogopterus, Belomys, Glaucomys, or Hylopetes. Considering the divergence time of the two Eupetaurus groups, the glaciations and the uplift of the Himalayas and Qinghai-Tibet plateau during the Pliocene-Pleistocene period might be the major factors affecting the present distribution of Eupetaurus along the Himalayas.

Animals↗
PubMed2004

Molecular phylogeny of the speciose vole genus Microtus (Arvicolinae, Rodentia) inferred from mitochondrial DNA sequences.

Voles of the genus Microtus represent one of the most speciose mammalian genera in the Holarctic. We established a molecular phylogeny for Microtus to resolve contentious issues of systematic relationships and evolutionary history in this genus. A total of 81 specimens representing ten Microtus species endemic to Europe as well as eight Eurasian, six Asian and one Holarctic species were sequenced for the entire cytochrome b gene (1140 bp). A further 25 sequences were retrieved from GenBank, providing data on an additional 23, mainly Nearctic, Microtus species. Phylogenetic analysis of these 48 species generated four well-supported monophyletic lineages. The genus Chionomys, snow voles, formed a distinct and well-supported lineage separate from the genus Microtus. The subgenus Microtus formed the strongest supported lineage with two sublineages displaying a close relationship between the arvalis species group (common voles) and the socialis species group (social voles). Monophyly of the Palearctic pitymyid voles, subgenus Terricola, was supported, and this subgenus was also subdivided into two monophyletic species groups. Together, these groupings clarify long-standing taxonomic uncertainties in Microtus. In addition, the "Asian" and the Nearctic lineages reported previously were identified although the latter group was not supported. However, relationships among the main Microtus branches were not resolved, suggesting a rapid and potentially simultaneous radiation of a widespread ancestor early in the history of the genus. This and subsequent radiations discernible in the cytochrome b phylogeny, show the considerable potential of Microtus for analysis of historical and ecological determinants of speciation in small mammals. It is evident that speciation is an ongoing process in the genus and that the molecular data provides a vital insight into current species limits as well as cladogenic events of the past.

Animals↗
PubMed2005

Systematics and evolution of the subfamily Gerbillinae (Mammalia, Rodentia, Muridae).

Although they represent a quarter of the mammalian species, the evolutionary relationships among as well as within, the main murid lineages are still controversial. The subfamily Gerbillinae is no exception as previous studies based on morphological, karyotypical, and allozyme characters are highly incongruent. Here, we present the first molecular phylogeny for gerbils based on cytochrome b and 12S rRNA mitochondrial genes. Results are largely congruent between the two genes as well as with the concatenated data set with most of the nodes being well-supported. Based on the topologies retrieved here, we (1) propose the identification of three main clades, (2) support the split of Tatera genus into an Asian and an African group, the latter including Gerbillurus species, and (3) provide some evidence towards the inaccuracy of subgeneric divisions within both Gerbillus and Meriones. In addition, the sharp contrast between the genetic characters and morphological data sets suggest high levels of convergence, probably as a result of strong environmental constraints imposed on these rodents adapted to arid and semi-arid regions. Finally, molecular datings for the various cladogenetic events are in good agreement with the known gerbilline fossil record and support an African origin with subsequent migrations to Asia.

Africa↗
PubMed2005

Molecular phylogeny of the African pygmy mice, subgenus Nannomys (Rodentia, Murinae, Mus): implications for chromosomal evolution.

Molecular phylogenies based on sequences of mitochondrial cytochrome b and nuclear IRBP genes are assessed on a comprehensive taxonomic sampling of African pygmy mice (subgenus Nannomys of the genus Mus). They represent a taxonomically diversified group of morphologically similar species, and exhibit an important chromosomal diversity, particularly involving sex-autosome translocations, one of the rarest and most deleterious chromosomal changes among mammals. The results show that the species sampled are genetically well differentiated, and that chromosomal rearrangements offer accurate diagnostic characters for discriminating most species. Furthermore, the species carrying different sex-autosome translocations appear monophyletic, suggesting that a genome modification allowing a higher rate of occurrence and/or fixation of such translocations took place, leading to the emergence of this lineage. In addition to taxonomic and biogeographical clarifications, we provide a temporal framework within which patterns of genic and chromosomal evolution are discussed.

Africa↗
PubMed2005

Mitochondrial phylogeny reveals differential modes of chromosomal evolution in the genus Tatera (Rodentia: Gerbillinae) in Africa.

The African gerbils of the genus Tatera are widespread and abundant throughout sub-Saharan Africa. There is still today a certain controversy concerning the taxonomy of these rodents and very few attempts have been made to assess their systematic relationships. The present paper introduces findings based on the partial sequences of cytochrome b (495 bp) and the 16S rRNA (469 bp) mitochondrial genes of six (T. robusta, T. nigricauda, T. vicina, T. leucogaster, T. valida, and T. kempi) species together with two additional taxa. We also report the karyotypes of T. vicina and T. leucogaster. We propose that T. vicina should be considered as a valid species and show the monophyly of the robusta species group, with the exclusion of T. leucogaster. Our results show there is a different chromosomal evolutionary pattern within the two major lineages, which is recognizable through molecular phylogenetics. One is characterized by karyotype stability and the other by a considerable number of chromosomal rearrangements. The lineage divergence coincides with the formation of the East African Rift. The processes that led to the origin of the East African species seem to be related to the subsequent climatic changes, which caused cyclic contraction and expansion of the savannah biomes. Furthermore, geological activities that characterized East Africa during Plio-Pleistocene may also have contributed to lineage divergence.

Africa↗
PubMed2005

Confrontation of morphological and molecular data: the Praomys group (Rodentia, Murinae) as a case of adaptive convergences and morphological stasis.

Phylogenetic relationships in a group of 21 African rodent species designated as the Praomys group (Murinae) were investigated using morphological characters and sequence data from the complete mitochondrial cytochrome b gene and nuclear IRBP gene fragment (840bp). The molecular results confirm the monophyly of the Praomys group, including the species Malacomys verschureni, while the other Malacomys species appear very divergent. The basal relationships within the Praomys group are poorly resolved, suggesting a rapid radiation at about 7-9 million years ago based on genetic divergence rates calibrated from the fossil record. Discrepancies between molecular and morphological results probably reflect of numerous convergences as well as variations in the rates of morphological evolution among lineages. Reconstructions of the ancestral character states suggest a savannah origin for the Praomys group, along with some morphological traits conserved by stasis in savannah taxa. At the same time, forest taxa seem to be characterized by an accelerated morphological evolution, with acquisition of convergent adaptive characters.

Adaptation, Biological↗
PubMed2006

Mitochondrial phylogeny of African wood mice, genus Hylomyscus (Rodentia, Muridae): implications for their taxonomy and biogeography.

This paper investigates the usefulness of two mitochondrial genes (16S rRNA and cytochrome b) to solve taxonomical difficulties within the genus Hylomyscus and to infer its evolutionary history. Both genes proved to be suitable molecular markers for diagnosis of Hylomyscus species. Nevertheless the resolving powers of these two genes differ, and with both markers (either analyzed singly or in combination), some nodes remain unresolved. This is probably related to the fact that the species emerged during a rapid diversification event that occurred 2-6 Myr ago (4-5 Myr ago for most divergence events). Our molecular data support the recognition of an "aeta" group, while the "alleni" and "parvus" groups are not fully supported. Based on tree topology and genetic divergence, two taxa generally recognized as subspecies should be elevated at the species level (H. simus and H. cf kaimosae). H. stella populations exhibit ancient haplotype segregation that may represent currently unrecognized allopatric species. The existence of cryptic species within H. parvus is questioned. Finally, three potentially new species may occur in West Central Africa. The Congo and Oubangui Rivers, as well as the Volta and Niger Rivers and/or the Dahomey gap could have formed effective barriers to Hylomyscus species dispersal, favoring their speciation in allopatry. The pronounced shifts in African climate during the late Pliocene and Miocene, which resulted in major changes in the distribution and composition of the vegetation, could have promoted speciation within the genus (refuge theory). Future reports should focus on the geographic distribution of Hylomyscus species in order to get a better understanding of the evolutionary history of the genus.

Animals↗
PubMed2006

Phylogeny and biogeography of the Petaurista philippensis complex (Rodentia: Sciuridae), inter- and intraspecific relationships inferred from molecular and morphometric analysis.

With modified DNA extraction and purification protocols, the complete cytochrome b gene sequences (1140 bp) were determined from degraded museum specimens. Molecular analysis and morphological examination of cranial characteristics of the giant flying squirrels of Petaurista philippensis complex (P. grandis, P. hainana, and P. yunanensis) and other Petaurista species yielded new insights into long-standing controversies in the Petaurista systematics. Patterns of genetic variations and morphological differences observed in this study indicate that P. hainana, P. albiventer, and P. yunanensis can be recognized as distinct species, and P. grandis and P. petaurista are conspecific populations. Phylogenetic relationships reconstructed by using parsimony, likelihood, and Bayesian methods reveal that, with P. leucogenys as the basal branch, all Petaurista groups formed two distinct clades. Petaurista philippensis, P. hainana, P. yunanensis, and P. albiventer are clustered in the same clade, while P. grandis shows a close relationship to P. petaurista. Deduced divergence times based on Bayesian analysis and the transversional substitution at the third codon suggest that the retreating of glaciers and upheavals or movements of tectonic plates in the Pliocene-Pleistocene were the major factors responsible for the present geographical distributions of Petaurista groups.

Animals↗
PubMed2006

Phylogenetics of the woodrat genus Neotoma (Rodentia: Muridae): implications for the evolution of phenotypic variation in male external genitalia.

Interspecific morphological variation in animal genitalia has long attracted the attention of evolutionary biologists because of the role genital form may play in the generation and/or maintenance of species boundaries. Here we examine the origin and evolution of genital variation in rodents of the muroid genus Neotoma. We test the hypothesis that a relatively rare genital form has evolved only once in Neotoma. We use four mitochondrial and four nuclear markers to evaluate this hypothesis by establishing a phylogenetic framework in which to examine genital evolution. We find intron seven of the beta-fibrinogen gene to be a highly informative nuclear marker for the levels of differentiation that characterize Neotoma with this locus evolving at a rate slower than cytochrome b but faster than 12S. We estimate phylogenetic relationships within Neotoma using both maximum parsimony and maximum likelihood-based Bayesian methods. Our Bayesian and parsimony reconstructions differ in significant ways, but we show that our parsimony analysis may be influenced by long-branch attraction. Furthermore, our estimate of Neotoma phylogeny remains consistent across various data partitioning strategies in the Bayesian analyses. Using ancestral state reconstruction, we find support for the monophyly of taxa that possess the relatively rare genital form. However, we also find support for the independent evolution of the common genital form and discuss possible underlying developmental shifts that may have contributed to our observed patterns of morphological evolution.

Animals↗
PubMed1998

Unilateral absence of the terminal nerve and distribution of gonadotropin-releasing hormone immunoreactive neurons in the brain of the common mole-rat (Cryptomys, Rodentia).

A paired terminal nerve with gonadotropin-releasing hormone-immunoreactive (GnRHir) neurons was found in five of six specimens of the Zambian common mole-rat (Cryptomys sp.). In these animals the distribution of GnRHir neurons in the CNS was approximately even on both sides. One adult female lacked a right terminal nerve, yet exhibited a comparable total number of GnRHir neurons, most of which were located on the left side of the brain, i. e., on that side where the terminal nerve was present. An additional population of GnRHir cells was detected in the area of the parafascicular and dorsomedial thalamic nuclei of three non-reproductive adult females, but not in young animals (one female, two males). The additional GnRHir cells, referred to as dark spot cells (DSCs) since their perikarya exhibit large or small strongly immunoreactive vacuoles, were present on both sides of the brain in equal numbers even in the specimen with unilateral absence of the terminal nerve. Obviously, the lack of one terminal nerve correlates with a drastic reduction in the number of ipsilateral genuine neurons but leaves the DSCs unaffected.

Animals↗
PubMedDate not supplied

Meriones libycus and Rhombomys opimus (Rodentia: Gerbillidae) are the main reservoir hosts in a new focus of zoonotic cutaneous leishmaniasis in Iran.

Following an epidemic of zoonotic cutaneous leishmaniasis (ZCL) around Badrood city, central Iran, Meriones libycus were found to be naturally infected with Leishmania major zymodeme MON-26 (= LON-1) in the villages of Matinabad and Fami, 12 km north-west of Badrood. This is the first isolation and characterization of L. major from M. libycus in Iran, in an area where ZCL has been present recently. M. libycus is probably the principal reservoir host in this area, but the main reservoir host further east is Rhombomys opimus. Parasites were not found in Hemiechinus auritis. The main, proven vector to humans and gerbils is Phlebotomus (Phlebotomus) papatasi. The close contact between vectors and reservoirs creates a very efficient cycle for the transmission of the disease.

Animals↗
PubMed2000

Molecular characterization and mitochondrial sequence variation in two sympatric species of Proechimys (Rodentia: Echimyidae) in French Guiana.

Variations in mitochondrial DNA characters were used to characterize two morphologically similar and sympatric species of Neotropical terrestrial rodents of the genus Proechimys (Mammalia: Echimyidae). We sequenced both cytochrome b (1140pb) and part of the control region (445pb) from four individuals of P. cuvieri and five of P. cayennensis from French Guiana, which allowed us to depict intra- and inter-specific patterns of variation. The phylogenetic relationships between the nine sequences evidence the monophyly of each species, and illustrate that more polymorphism might exist within P. cuvieri than within P. cayennensis. By developing species-specific primers to amplify a fragment of the cytochrome b gene, we were able to identify 50 individuals of Proechimys spp. caught in two localities of French Guiana. In both sites of primary rainforests, we showed that the two species live in syntopy, and this observation emphasizes the need to document ecological differences which should exist in order to diminish inter-specific competition.

Journal Article↗
PubMed2001

Biochemical genetic markers to identify two morphologically similar South African Mastomys species (Rodentia: Muridae).

The two common southern African mice species (Mastomys coucha and M. natalensis) are morphologically almost identical, making field identification impossible at present. Specimens from two localities were collected and tissue and blood samples taken. The habitat type of each locality was studied, and a distribution map compiled. A definite correlation between biome-type and species range was found to be present. Three isozyme markers were identified: glucose phosphate isomerase in liver, and two general (non-specific) protein coding loci in muscle. In addition, we also identified species characteristic haemoglobin components in both species. This is the first study to report genetic variation within, and differentiation between these species. Our results are of medical importance because Mastomys coucha carries bubonic plague and M. natalensis carries Lassa Fever.

Journal Article↗
PubMed2003

Extensive mtDNA variation within the yellow-pine chipmunk, Tamias amoenus (Rodentia: Sciuridae), and phylogeographic inferences for northwest North America.

The yellow-pine chipmunk, Tamias amoenus, is common in xerophytic forests throughout much of northwest North America. We analyzed cytochrome b sequence variation from 155 individuals representing 57 localities across the distribution of T. amoenus including 10 additional species of Tamias. Maximum likelihood and parsimony tree estimation methods were used in conjunction with nested clade analysis to infer both deep and population-level processes. Our results indicate that two currently recognized subspecies of T. amoenus (T. a. canicaudus and T. a. cratericus) are not nested within other samples of T. amoenus. Maximum uncorrected levels of intraspecific sequence divergence within remaining samples of T. amoenus are >7%. Substantial geographic variation is characterized by 12 well-supported clades that correspond to distinct mountain ranges, but do not necessarily follow existing subspecific taxonomy. Significant association between geography and genealogy was detected within many of these clades and can be attributed to different population-level processes including past fragmentation, recent range expansion, and isolation by distance.

Animals↗
PubMed2004

Nuclear DNA phylogeny of the squirrels (Mammalia: Rodentia) and the evolution of arboreality from c-myc and RAG1.

Although the family Sciuridae is large and well known, phylogenetic analyses are scarce. We report on a comprehensive molecular phylogeny for the family. Two nuclear genes (c-myc and RAG1) comprising approximately 4500 bp of data (most in exons) are applied for the first time to rodent phylogenetics. Parsimony, likelihood, and Bayesian analyses of the separate gene regions and combined data reveal five major lineages and refute the conventional elevation of the flying squirrels (Pteromyinae) to subfamily status. Instead, flying squirrels are derived from one of the tree squirrel lineages. C-myc indels corroborate the sequence-based topologies. The common ancestor of extant squirrels appears to have been arboreal, confirming the fossil evidence. The results also reveal an unexpected clade of mostly terrestrial squirrels with African and Holarctic centers of diversity. We present a revised classification of squirrels. Our results demonstrate the phylogenetic utility of relatively slowly evolving nuclear exonic data even for relatively recent clades.

Animals↗
PubMed2004

Historical biogeography at the crossroads of the northern continents: molecular phylogenetics of red-backed voles (Rodentia: Arvicolinae).

Evolutionary relationships of red-backed voles and their relatives were examined and used to test biogeographic hypotheses. Sequences of the mitochondrial cytochrome b gene were obtained for 25 individuals representing Alticola macrotis, Clethrionomys californicus, C. gapperi, C. glareolus, C. rutilus, and C. rufocanus. These were combined with 21 partial sequences from GenBank for C. regulus, C. rex, C. rufocanus, C. rutilus, Eothenomys imaizumii, E. melanogaster, Phaulomys andersoni, and P. smithii. Complete sequences of three species of Microtus (M. montanus, M. oeconomus, and M. pennsylvanicus), representative species of other arvicoline genera (Myopus, Synaptomys, Arvicola, Ellobius, Ondatra, Lemmus, Dicrostonyx, and Phenacomys), and a sigmodontine representative (Peromyscus) were included as outgroups. We used maximum parsimony, maximum likelihood, distance, and Bayesian based methods and conducted statistical tests on proposed hypotheses of phylogenetic relationships and biogeographic histories. A close relationship of species representing the genera Alticola, Clethrionomys, and Eothenomys was supported (Clethrionomyini); however, the genus Clethrionomys was paraphyletic with respect to both Alticola and Eothenomys. Three major clades were identified as Asian (Eothenomys andersoni, E. smithii, C. rex, C. regulus, and C. rufocanus), Trans-beringian (Alticola macrotis, C. californicus, C. gapperi, C. glarelolus, and C. rutilus), and Taiwanese (E. melanogaster). These results are consistent with the fossil record which indicates an initial diversification in Asia followed by colonization of the Nearctic on at least two occasions. The holarctic species, C. rutilus, appears to have either reinvaded Asia from North America or colonized North America more recently (late Pleistocene) than the two species of Clethrionomys (C. gapperi and C. californicus) that are endemic to North America (early to mid-Pleistocene). Finally, C. gapperi, appears to be comprised of an eastern and a western species, the former with affinities to the Asian C. glareolus and the latter more closely related to C. californicus.

Animals↗
PubMed2003

Metabolism and thermoregulation in the Cabrera vole (Rodentia: Microtus cabrerae).

Metabolism and thermoregulation were studied for the first time in the Cabrera vole (Microtus cabrerae), an endemic and threatened rodent of the Iberian Peninsula. Low values of resting metabolic rate (RMR) were registered (1.13 mlO(2) g(-1) h(-1)) at the lower limit of the thermoneutral zone (TNZ) (around 33.5 degrees C). Body temperature increased near the TNZ up to 37.3 degrees C but remained stable, around 36 degrees C, at ambient temperatures below 25 degrees C. Values of thermal conductance remained quite stable at ambient temperatures of 10-25 degrees C (0.144-0.160 mlO(2) g(-1) h(-1) degrees C) and increased to 0.301 mlO(2) g(-1) h(-1) degrees C at 33.5 degrees C. Data revealed that M. cabrerae developed a highly adaptive ability of conserving energy and lowering the metabolic cost of thermoregulation at high ambient temperatures, allowing the body temperature to approximate that of the environment and exhibiting low resting metabolic rate and high conductance.

Animals↗