Dasymys spp. – African Marsh Rat (original) (raw)
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mamm, 2002
This study examines inter-population variation in the subspecies of water rat Dasymys incomtus in eastern and extreme southwestern South Africa. Dasymys incomtus is widespread but its distribution is limited to water sources. Two techniques, protein electrophoresis and traditional cranial morphometrics, were used to investigate South African D. /. incomtus populations with known differences in chromosome numbers (2n = 38 from the KwaZulu-Natal and 2n = 46 from the Northern Province). Both electrophoretic and morphometric data confirmed the cytogenetic results, with specimens from the Northern Province forming one group and specimens from the KwaZulu-Natal forming another. A high F CT value (0.424), low Nm value (0.068) and the presence of three fixed alleles (Aspartate Aminotransferase-1, Glycerol-3-phosphate and Purine-nucleoside) across the populations indicated the genetic separation of the Kwa-Zulu-Natal and Northern Province localities. Morphological separation between the populations occurred in five cranial characters: condylobasal length, palatal length, greatest mandible length, incisor to condyle length and ZAE, as evidenced by their high F-values and their high loadings on the first principal component. Carson's population flush theory, Wright's isolation by distance theory and the role of paleoclimates in conjunction with habitat constraints on population movement were considered as possible explanations for the patterns seen in this study. Resume.-Cette e*tude a permis d'examiner des variations entre populations du rat d'eau Dasymys incomtus. Les individus appartenant a cette espece sont tres ropandus en Afrique mais ont une ^partition qui se limite aux zones humides. Deux techniques, Felectrophorese des proteines et la morphomotrie classique cränienne ont £te utilises pour examiner d'eVentuelles differences entre des specimens pr&entant des nombres chromosomiques distincts selon Gordon (1991) (2n = 38 pour la sous-espece du KwaZulu-Natal et 2n = 46 pour celle de la Northern Province). D'une maniere g£n6rale, les donne*es d'ölectrophorese et de morphometrie confirment les r£sultats cytt^notiques, les specimens de la Northern Province formant un groupe, ceux du KwaZulu-Natal un autre. Une valeur F^ haute (0.424), une valeur Nm basse (0.068) et la prosence de trois alleles fixes (AAT-1, GDP et PNP) dans les populations ont montro une sopara
Geographic variation in the Tete veld rat Aethomys ineptus (Rodentia: Muridae) from southern Africa
Journal of Zoology, 2001
The Tete veld rat Aethomys ineptus Thomas & Wroughton, 1908 is a newly recognized, widely distributed species in southern Africa. Analysis of geographic variation among samples of A. ineptus from southern Africa across a more comprehensive geographical range than has previously been considered suggests that the species has a clinal pattern of variation in which overall cranial size was positively and signi®cantly correlated with longitude. While the suggested clinal pattern of cranial size variation may be valid, the status of some operational taxonomic units, however, may require further re®nement involving additional sampling as well as other systematic techniques, such as DNA analysis, cytogenetics and geometric morphometrics. These additional studies may have to include geographic information systems, step-wise multiple regression, and trend-surface analysis involving a wide range of environmental parameters to identify factors that may explain the nature and extent of the delineated pattern of geographic variation within A. ineptus from southern Africa. Consequently, the seven previously recognized subspecies recently assigned to A. ineptus in southern Africa (A. chrysophilus tzaneenensis Jameson, 1909; A. c. pretoriae
Organisms Diversity & Evolution, 2023
The Mashona mole-rat, Fukomys darlingi (Thomas, 1895), is a little studied social African mole-rat (Bathyergidae) from south-astern Africa. Here, we present an integrative study characterizing the genetic diversity of populations assigned to F. darlingi with special focus on animals from Nsanje, southern Malawi. These mole-rats show pronounced differences in body mass and general appearance compared to nominate F. darlingi from Zimbabwe and Mozambique, but their taxonomic status has so far remained unclear. A genetic analysis encompassing all major lineages of the genus Fukomys suggests that this population indeed represents a deeply nested lineage within the F. darlingi clade. The karyotype of the Nsanje molerats also corresponds to that of the nominate form, being 2n = 54. While both nuclear and mitochondrial data agree about the assignment of the Nsanje mole-rats to F. darlingi, our analyses revealed substantial mitonuclear discordance for other branches within the Fukomys phylogenetic tree. Nsanje mole-rats are significantly larger than nominate F. darlingi and their ontogeny and reproduction closely resemble similar-sized congeneric species rather than the nominate population. The somatic growth of the Nsanje form is the slowest of all African mole-rats. The maximum life span of F. darlingi is at least 19 years. The observed differences between nominate F. darlingi and mole-rats from Nsanje may be attributed mainly to their different body mass. Our study highlights the advantages of an integrative approach for understanding the diversity of African mole-rats and emphasizes the great intraspecific variability that may be encountered in these underground-dwelling rodents.
Journal of Urban Ecology
Three species of Rattus, Norway rat (R. norvergicus), black rat (R. rattus) and Asian house rat (R. tanezumi) are currently known to occur in South Africa. The latter two species are cryptic and form part of the Rattus rattus species complex. Historically, R. norvegicus has been reported to occur along the coast and in urban centres, R. rattus is widespread in most urban areas, except in the drier areas, while R. tanezumi was only recorded to occur in the country (and Africa) ca. 15 years ago, and its distribution remains unknown. The aim of this study was to predict the potential distribution of R. tanezumi in South Africa and assess how it overlaps with that of R. norvegicus and R. rattus using species distribution modelling. Rattus tanezumi was predicted to mainly occur in most inland urban areas and along the coast. The distribution of R. rattus was as expected, in contrast, the predicted range of R. norvegicus was not restricted to the coast but also included inland urban areas...
Zoological Journal of the Linnean Society, 2012
Our study combined a mitochondrial cytochrome b phylogeny with cranial measurements from giant pouched rats collected across sub-Saharan Africa. The mitochondrial phylogeny resolves two West African clades and a clade with east and central Africa representatives. This last clade can be further divided into four subclades. Altogether they represent six species (Cricetomys gambianus, Cricetomys ansorgei, Cricetomys emini, and three undescribed taxa) that can be distinguished on the basis of their mitochondrial DNA sequences and craniometry. In the absence of adequate craniometric data the existence of Cricetomys kivuensis cannot be confirmed by our data. Our combined molecular and craniometric data allowed us to broadly delineate the distribution ranges of the detected species. Cricetomys gambianus occurs in the savannah and forest clearings of West Africa. Cricetomys ansorgei is distributed in the savannah of East and southern Africa. Cricetomys emini, as currently recognized across the Guineo-Congolian forest of Africa, is shown to be diphyletic. Cricetomys sp. 1, a separate operational taxonomic unit closely resembling C. emini, occurs in the forest zone of West Africa. An undescribed sister-species of C. ansorgei, Cricetomys sp. 2, occurs in the forest of Central Africa along the left bank of the Congo River. Cricetomys sp. 3 occurs on the right bank of the Congo River from Cameroon to the Republic of Congo, whereas the true C. emini also occurs on the right bank of the Congo River but appears to be restricted to the Democratic Republic of Congo. Cranial phenotype within the genus tends to conform to ecological zonation (either forest or savannah) rather than to phylogenetic affiliation of the species concerned, suggesting that diversifying selection across environmental gradients could be responsible for biological diversification within the genus.
Molecular Phylogenetics and Evolution, 2004
Cryptomys represents the most speciose and widely distributed genus of the Bathyergidae (Mammalia; Rodentia), a family of mole-rats endemic to sub-Saharan Africa. Throughout its range in southern, central, and western Africa, Cryptomys displays diversity in terms of morphology, patterns of behavior, and chromosome number, thus complicating the systematics of the group. A molecular phylogeny was obtained by separate and combined analyses of the mitochondrial 12S rRNA and intron I of the nuclear transthyretin gene for chromosomally and geographically diverse populations of Cryptomys. Our results show that Cryptomys sensu lato is comprised of two distinct and divergent monophyletic clades: hottentotus and mechowi. Based on our analyses, we propose the elevation of the mechowi clade to the genus Coetomys, retaining Cryptomys as the generic epithet of the South African hottentotus clade. This is supported by: (1) reciprocal monophyly of the two lineages based on independent datasets, (2) the level of sequence divergence observed between these lineages relative to other genera (i.e., Bathyergus and Georychus), and (3) different patterns of chromosomal evolution, with Cryptomys sensu stricto being karyotypically conserved (2N=54) and Coetomys exhibiting high karyotypic diversity (2N=40–78).
Allozyme differentiation and systematics of the endemic subterranean mole rats of South Africa
Biochemical Systematics and Ecology, 1987
We have analyzed allozyme differentiation, encoded by 20 putative gene loci, of three genera and four currently accepted species of Southern African mole rats, Bathyergidae (Cryptomys hottentotus hottentotus, C. hottentotus natalensis, C. hottentotus damarensis, Georychus capensis, Bathyergus suillus and B. janetta). Two major results are indicated: (a) genetically the family reflects distinct homozygosity (H=0.019, range 0.00-0.05) as is typical for underground fossorial mammals and (b) remarkable large genetic distances exist between the six taxa analyzed (D=1.865, range 0.547-2.917). These results suggest that homoselection operates in the underground ecotope in accordance with the niche width variation hypothesis, and that bathyergid systematics needs urgent revision, particularly the genus Cryptomys. The three subspecies of Cryptomys appear to be at least three different species, possibly even falling into two genera. The adaptive radiation of bathyergids started at least in Miocene times, but probably began earlier in the Oligocene as indicated by the fossil record. lying red soil on dolorite. Consolidated red Kalahari sands. Sandstones near highway, Du Toits Pass. See above. Red clay soil near the Campus of the University of Cape Town. Cultivated alluvial sands and arenosols. Cultivated arenosols, soft sands. Genetic Distance Between Populations and Species Coefficients of genetic similarity, /, and genetic distance, D, were calculated on the basis of the 20 shared loci for paired combinations of all 11 populations and six taxa, based on the normalized identity of genes between each pair of populations or species [20]. The results are given in Table 6a, b. The mean value of D between all 11 populations of the six taxa was very large D=0.45, range 0.055-2.943. Remarkably, the genetic distance was also very large between the three subspecies of Cryptomys hottentotus. The largest genetic distance within Cryptomys was between C. h. damarensis and the other two subspecies, D=1.257. Even within species, genetic distances may be very large.
Background and aim: African Greater Cane (ACG) rat populations are widely distributed across Africa but the ancestral origin of populations inhabiting different geographical regions is unknown. There is currently no information available on the genetic differentiation of these populations resulting from long-time geographical isolation, environmental and anthropogenic pressures they face in each region. This limits our ability to understand potential speciation processes in AGC and their implications for their conservation and of other small wild mammals exposed to similar ecological conditions in the savannah biomes in Africa. Methods: We analyzed mitochondrial genes targeting the D-loop region of AGC samples from two blocks of the Eastern Arc Mountains in Tanzania (eastern), three agro-ecological zones in Ghana (western) and four sites in South Africa (southern) to characterize the phylogeographical patterns of the species. Results: AGC populations from Tanzania revealed higher haplotype diversity than those from the two other régions. Analysis of variance (AMOVA) revealed higher genetic variations within than between populations in all geographic regions. Demographic history analysis revealed a negative and significant Tajima's D for a single southern African population as well as close relatedness with the Eastern Africa populations, suggesting a common ancestral origin. Conclusion: This is the first study to compare maternal lineages of AGC populations from eastern, western and southern Africa and provides a basis for future genetic studies of the species, its evolutionary ecology and the conservation of these populations across their range. Conservation implications: Evidence of recent population size expansion underpinned by high genetic diversity observed in the Uluguru urban (Tanzania) Guinea savannah (Ghana) and Kwazulu Natal (South Africa) populations suggest that the AGC populations are not currently threatened, consistent with the current IUCN status. Also, the distinct haplotypes observed in each region suggest that the populations can be managed as meta-populations, thus providing opportunities for potential local game-farming programs.
A revised systematic checklist of the extant mammals of the southern African subregion
2003
A. & Robinson, T.J. 2003. A revised systematic checklist of the extant mammals of the southern African subregion. Durban Museum Novitates 28: 56-106. The current paper presents a revised, annotated, systematic checklist of 351 extant mammal species, in 190 genera, currently known to occur in southern Africa (south of the Zambezi and Cunene Rivers) and its coastal waters. The checklist includes each species' scientific and English common name, details concerning original description, occurrence or possible occurrence in each of the seven countries falling within the Subregion, and, where relevant, the IUCN global Category of Threat. Taxonomic notes, together with the relevant literature, are provided to justify the proposed classification adopted at each hierarchical level. The new classification we present is founded on the philosophy of phylogenetic systematics, and represents not only a summary of new information, but also tremendous advances in the methods and philosophy of mammalian systematics during the past two decades.