The pouched mouse, Saccostomus campestris Peters, 1846 from southern Africa shows a high degree of karyotypic variation where up to 16 variants (2n = 30–50) have been reported. This has led to a systematic uncertainty that the present study attempts to assess using: 1) cytochrome b (cyt b; 1077 bp) and 16S rRNA (528 bp) partial sequences; 2) G-banding cytogenetic data; and 3)geometric morphometric data of various views of the cranium and mandible. The results from these multidisciplinary analyses are broadly similar with phylogenetic analyses of the molecular data revealing the presence of two major lineages. The first lineage comprises the high diploid numbered 2n = 46 cytotype from KwaZulu-Natal Province, South Africa that is considered to be ancestral. The second lineage consists of multiple inland populations that are subdivided into: 1) a sub-lineage comprising samples from a large semi-arid area in the west; and b) a sub-lineage of small distinct populations of low migrations from the east. The cytogenetic data suggest that karyotypic variation within S. campestris from southern Africa is due to autosomal Robertsonian fusions, with evidence of geographic structuring where cytotypes with high diploid numbers originate from the mesic east, while those with low diploid numbers originate from the arid west. The reduction in chromosome number appears to be due to adaptation to cold and dry conditions in the arid west. The X-chromosome revealed three variants that arose from a single pericentric inversion followed by the addition of genetic material, possibly heterochromatin. Variant 1 is only present in the ancestral cytotype and is found in all cytotypes throughout southern Africa, variant 2 is found in cytotypes from areas with < 600 mm of annual rainfall, while variant 3, although only found in females, is sympatric with variant 2. Geometric morphometric analysis of karyotyped specimens showed no discernible patterns of variation among karyotypic variants except for some subtle but equivocal indication of the morphological distinctiveness of the 2n = 46 cytotype from KwaZulu-Natal. Collation of the molecular, cytogenetic, and geometric morphometric data in the present study suggest that S. campestris from southern Africa is monotypic. / Dissertation (MSc)--University of Pretoria, 2011. / Zoology and Entomology / unrestricted

Saccostomus campestris display sexual disparity in the use of summer daily torpor in response to energy stress. The hypothesis that males may compensate for a limited heterothermic capacity with lower normothermic body temperatures by maintaining lower resting metabolic rates relative to females was tested. Furthermore, the influence of testosterone on torpor incidence in males was investigated. Body temperature (T[b]) and oxygen consumption (VO₂) were measured at various ambient temperatures (Tₐ) and were compared between the sexes under food ad libitum and food restriction treatments. There were no significant differences in T[b] and VO₂ between sexes under food ad libitum treatment. Under food restriction there were pronounced sex differences in the employment of heterothermy. Females defended a lower setpoint T[b] for torpor (ca. 25°C), than males (ca. 29°C), and also employed torpor more frequently than males. Non-torpid males did, however show slight reductions in VO₂ under food restriction. The effect of testosterone on daily torpor was investigated by comparing minimum T[b]and torpor frequency of castrated mice implanted with testosterone-filled (experimental) and saline-filled (control) silastic capsules in response to food ad libitum and food restriction treatments. Testosterone inhibited torpor in males. The majority of control animals employed torpor under both food ad libitum and food restriction diets. It was concluded that although the animals were capable of shallow, summer torpor, it was confined to moderate ambient temperatures and was not used at low Tₐ's where several animals became pathologically hypothermic. Females derive energetic benefits from the use of torpor whereas males may partially compensate for their limited heterothennic capacity by a reduction in resting metabolic rates, accompanied by moderate reductions in body temperature during energetically stressful periods. The difference in the capacity for daily heterothenny between sexes was attributed to differences in their reproductive physiology. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2000.

The main aim of the current study was to determine the prevalence and diversity of potentially zoonotic bacterial genera in accurately identified indigenous rodents from South Africa. Bacterial prevalence and diversity were determined by PCR amplification and sequence analyses. Rodents were molecularly identified by amplification and sequence analysis of the mitochondrial cytochrome b gene region. Three species (Aethomys ineptus, Mastomys coucha and Otomys angoniensis) belonging to murid species complexes were identified. Furthermore, phylogenetic analyses revealed that both the proposed subspecies (R. dilectus dilectus and R. d. chakae) within the recently erected Rhabdomys dilectus occur in Hammanskraal and at the University of Pretoria Experimental farm, both in the Gauteng Province of South Africa. An overall bacterial prevalence of 38.6 % was observed in kidney samples of commensal and natural indigenous rodents after molecular screening with broad range 16S rRNA gene primers. Nucleotide sequence analyses identified a diverse range of bacterial genera namely, Bartonella, Anaplasma, Helicobacter, Burkholderia, Streptococcus, Aerococcus and Lactobacillus. Some members of these genera have been identified as causative agents of human and animal diseases, being transmitted either through environmental contamination or through haematophagous arthropod vectors. Subsequent genus-specific bacterial screening focussed on vector-borne genera identified in the commensal and natural rodent populations sampled. Bartonella prevalence and genetic diversity was compared between a natural and commensal population of the southern multimammate mouse (M. coucha) using two gene regions (Citrate synthase gene and NADH dehydrogenase gamma subunit gene). A significantly higher infection prevalence was detected in the commensal population (92.9 %) as compared to the natural population (56.9 %). No differences however, were detected between infection status and the ectoparasite loads calculated for both rodent populations. Apart from several novel Bartonella strains identified in both M. coucha populations, phylogenetic analyses also identified a species of known zoonotic potential (B. elizabethae) in both populations. The present study represents one of the first to screen indigenous rodents for tick-borne members of the bacterial family Anaplasmataceae. Anaplasma bovis-like DNA was detected in five of the six rodent species sampled (A. ineptus, Lemniscomys rosalia, M. coucha, O. angoniensis and R. dilectus) at an overall prevalence of 39.2 %. The potentially zoonotic Ehrlichia ewingii was detected in M. coucha samples only at a prevalence of 5.3 %. The diverse bacterial genera detected in commensal and natural populations of indigenous rodents comprise members of zoonotic potential and agricultural significance, highlighting the importance of continuous disease surveillance of indigenous rodents. / Dissertation (MSc)--University of Pretoria, 2014. / National Research Foundation (NRF) / Zoology and Entomology / MSc / Unrestricted