Genetic variation inRhabdomys pumilio(Sparrman 1784) - an allozyme study

Abstract

The striped-mouse, Rhabdomys pumi/io, is widely distributed throughout southern Africa. It prefers grasslands but is also found in vlei areas and dry river beds and its attraction to cultivated land has resulted in extensive damage to plants. An allozyme study of R. pumi/io populations in different regions of southern Africa was undertaken to evaluate the genetic structure wilhin and between 23 populations and to draw conclusions about the taxonomic status of populations within this species. Fifteen of the 26 loci examined were polymorphic. The mean heterozygosity (0.073) was high for a mammal, although relatively low heterozygosities (0.036-0.054) were recorded for three localities from the peninsular region of the Western Cape. The high mean value for local genetic differentiation (F 51) of 0.459 and the low mean value for the effective number of migrants (Nm) of 0.179 indicated low levels of gene flow between the different localities of R. pumilio. The negative, near zero F, 5 value of-0.01 indicated a balance between heterozygotes and homozygotes. Rogers (1972) genetic similarity ranged between 0.796 and 0.988, and Nei's (1978) unbiased genetic distance varied between 0.000 and 0.189 between the samples of R. pumilio. The phenogram based on Nei's (1978) unbiased genetic distance showed some degree of geographical subgrouping. The Mantel test indicated a Significant relationship between the F. 1 values and the geographical distances between sample pairs, supporting an isolation by distance model for R. pumilio. Although the genetic evidence for geographical divergence does suggest the possible existence of subspecies, this remains to be substantiated.

Isozyme and allozyme markers distinguishing two morphologically similar, medically important Mastomys species (Rodentia: Muridae)

“…All of the measures have increased slightly with the addition of the new material, with pair-wise F ST values between the species of 0.882 (Vaal and Richards Bay populations) and 0.743 (La Lucia and Montgomery Park populations) indicating large amounts of differentiation between the two species by the abovementioned criteria (Table 3). As expected, this is higher than the F ST value of 0.375 for populations of O. irroratus [13] and 0.459 for populations of the striped field mouse R. pumilio [14]. These are comparable to the F ST values of 0.558 between the two M. coucha populations, and 0.228 between the two M. natalensis populations.…”

“…These values put these two species in the lower range of rodent variation (Figure 1). A much higher mean heterozygosity (0.073) was obtained by Mahida et al [14] in their genetic assay of the grassland specialist, Rhabdomys pumilio . This is interesting, as Rhabdomys is a species that prefers a more pristine habitat than the opportunistic and pioneering multimammate mice.…”

“…These are comparable to values reported for other rodent species. Johnson and Selander [12] obtained 7.9% in the Heteromyid Dipdomys , 17.4% for Otomys irroratus [13], 16.1% for Rhabdomys pumilio [14], and 6.7% for Oryzomys palustris [15]. The values for M. coucha are lower than those for M. natalensis , and although the lowest value of 5.7% for the Vaal population could be attributed to small sample size, one could expect that the much larger geographic range of M. natalensis (from southern Africa right through to west Africa) and the greater diversity of biome type would give this species a somewhat larger degree of genetic variation.…”

Community inertia of Quaternary small mammal assemblages in North America

“…For the time scale between 1,000 and 3,000 ybp, the empirical data fall in the same range as the neutral model for M Ͼ Ͼ 4, but well above the range for M Յ 4. M Ͼ Ͼ 4 would have to be considered to be a much higher migration rate than the rate of M Ͻ 1 most small mammals experience (43,44), especially when the biases of the F ST estimation method (45) are taken into account. For time periods Ͼ3,000 years, the empirical data are all well above the neutral simulations, even for the highly unrealistic scenario of M ϭ J (m ϭ 1.0, complete replacement of the community by migrants each year or total panmixia).…”

Evidence of a contact zone between twoRhabdomys dilectus(Rodentia: Muridae) mitotypes in Gauteng province, South Africa

“…Karyotypic and allozyme studies revealed the presence of two karyotypes (2n = 46 and 2n = 48) and restricted gene flow between widely separated populations in southern Africa (Ducroz et al 1999;Mahida 1999;Taylor 2000). Breeding and behavioural studies were also not able to provide conclusive evidence on species and subspecies boundaries (Pillay 2000a;b;Pillay et al 2006).…”