We conducted a phylogenetic analysis of genetic and anatomical data focusing on golden moles (Chrysochloridae) and tenrecs (Tenrecidae). Our results support the now well-resolved topology for extant tenrecids, in addition to the paraphyly of 'Chrysochlorinae' and the genera Chrysochloris and Chlorotalpa as traditionally used. Carpitalpa arendsi is the sister taxon to Neamblysomus; together, they compose the sister clade of Amblysomus. Unexpectedly, Calcochloris obtusirostris is the sister taxon of Chrysospalax. The oldest divergence within crown Chrysochloridae is likely to be the node separating Eremitalpa-Huetia or Eremitalpa alone from the remaining species. A Chrysochloris-Cryptochloris root appears most frequently under equally weighted parsimony or with few or no sampled tenrecids, suggesting that it is artefactual. The tropical genus Huetia is among the most widely distributed and anatomically polymorphic in our sample. Eremitalpa and Huetia have a relatively unspecialized hyoid apparatus and short angular process of the dentary. These elements in Huetia show a particular resemblance to those of the Namibian fossil Namachloris, which we reconstruct as a stem chrysochlorid. Crown chrysochlorids are geologically younger than crown tenrecids and probably diversified in the Miocene around the same time as the tenrecid genus Microgale. Fossils of both groups from Eocliff in Namibia are probably late Eocene to early Miocene in age.
The naked mole-rat (Heterocephalus glaber) has fascinated zoologists for at least half a century. It has also generated considerable biomedical interest not only because of its extraordinary longevity, but also because of unusual protective features (e.g. its tolerance of variable oxygen availability), which may be pertinent to several human disease states, including ischemia/reperfusion injury and neurodegeneration. A recent article entitled 'Surprisingly long survival of premature conclusions about naked mole-rat biology' described 28 'myths' which, those authors claimed, are a 'perpetuation of beautiful, but falsified, hypotheses' and impede our understanding of this enigmatic mammal. Here, we re-examine each of these 'myths' based on evidence published in the scientific literature. Following Braude et al., we argue that these 'myths' fall into four main categories: (i) 'myths' that would be better described as oversimplifications, some of which persist solely in the popular press; (ii) 'myths' that are based on incomplete understanding, where more evidence is clearly needed; (iii) 'myths' where the accumulation of evidence over the years has led to a revision in interpretation, but where there is no significant disagreement among scientists currently working in the field; (iv) 'myths' where there is a genuine difference in opinion among active researchers, based on alternative interpretations of the available evidence. The term 'myth' is particularly inappropriate when applied to competing, evidence-based hypotheses, which form part of the normal evolution of scientific knowledge. Here, we provide a comprehensive critical review of naked mole-rat biology and attempt to clarify some of these misconceptions.
Studies detailing the anatomy of the brain of the golden moles are few. A recent study indicated that in the Hottentot golden mole (a member of the Amblysominae clade), there was a broad, atypical, distribution of cholinergic interneurons in the olfactory bulb, cerebral cortex, hippocampus and amygdala. To determine whether this broad distribution of cholinergic neurons is shared by other species of golden mole, we here examine the brain of the Cape golden mole (a member of the Chrysochlorinae clade, representing the second major clade within the family Chrysochloridae). Our analyses indicates the presence of a similar widespread distribution of cholinergic interneurons in the Cape golden mole. Thus, we conclude that these features are derived morphological traits in the brains of golden moles. In addition, we describe the nuclei generally considered to be part of the typical cholinergic system in mammals. Whereas the vast majority of these generally reported cholinergic nuclei were the same as recorded in other Eutherian mammals, it was noted that the cholinergic nuclei involved in oculomotion were substantially reduced in size, or absent in the case of the abducens nucleus. In addition, there was an absence of the cholinergic medial septal nucleus, but the presence of a cholinergic lateral septal nucleus. The laterodorsal and pedunculopontine tegmental nuclei evince regions where the cholinergic neurons are densely packed. These are atypical features of the mammalian cholinergic system, which when combined with the widespread atypical distribution of cholinergic interneurons, reveals a family-specific complement of cholinergic nuclei in the Chrysochloridae.
South Africa harbours remarkable biological diversity with three of the 34 recognised global biodiversity hotspots placed within its borders. One of these is the Succulent Karoo, which together with the Nama-Karoo, forms the Greater Karoo region. Notwithstanding a paucity of studies from this region, it would appear that, although mammal diversity is low, endemism is high. Here, as part of the Karoo BioGaps project, we use a molecular approach to assess small mammal diversity and endemism in the Karoo. We focus on rock rats (Micaelamys) and elephant shrews (Elephantulus and Macroscelides). Using a DNA-informed identification approach, we reveal two, well supported, monophyletic clades of Micaelamys; one that corresponds to M. granti. Our study is the first to publish sequence data for this species. Furthermore, when unverified records are excluded, the range of M. granti is far smaller (∼99 000 km2) than that given by the IUCN red list assessments (236 027 km2), which lends support to the species being a Karoo endemic. Our macrosceledid samples grouped into four well supported clades of the genera Elephantulus and Macroscelides. Very high intraspecific diversity was present within E. pilicaudus compared with other species in our study and this newly described species may harbour cryptic diversity. Our geographic analyses confirm that the range of this species, previously considered to be a Nama-Karoo endemic, extends beyond this region. This study adds more information to the nominal data currently available for the species, Elephantulus pilicaudus.
Commercial plantations and alien tree invasions often have substantial negative impacts on local biodiversity. The effect of plantations on faunal communities in the fire-adapted fynbos vegetation of the Cape Floristic Region biodiversity hotspot is not yet well quantified. We studied small mammal community structure in alien Pinus radiata plantations and adjacent fynbos regenerating after clear-felling of plantations on the Cape Peninsula, South Africa. Small mammal sampling over 1,800 trap-nights resulted in 480 captures of 345 individuals (excluding recaptures) representing six species. Significantly more species, individuals (12 X) and biomasses (29 X) of small mammals occurred on recovering fynbos sites compared to plantations. This was commensurate with a higher diversity of plant growth forms, vegetation densities and live vegetation biomass. Only one small mammal species, the pygmy mouse (Mus minutoides), was consistently trapped within plantations. Fynbos sites were dominated by three small mammal species that are ecological generalists and early successional pioneer species, rendering the recovering fynbos slightly depauperate in terms of species richness and evenness relative to other studies done in pristine fynbos. We make three recommendations for forestry that would facilitate the restoration of more diverse natural plant communities and progressively more diverse and dynamic small mammal assemblages in a key biodiversity hotspot.
Golden moles are small, fossorial, and primarily insectivorous mammals mostly endemic to South Africa. They belong to an ancient African clade of placental mammals (Afrotheria) that likely radiated from an herbivorous ancestor. Nearly half of the 21 golden mole species are listed as threatened; but remarkably little is known about their basic biology and gastrointestinal tract (GIT) morphology. This study provides a morphometric and histochemical analysis of the GIT of seven chrysochloridae species, including three threatened taxa. Macroscopically, all species examined had simple GITs with simple, wholly glandular stomachs and no cecum. Histologically, the pylorus was dominated by parietal cells. Neutral mucin cells were found on the luminal surface and in the gastric pits, while mixed acid and neutral mucin cells were found in the proximal parts of the gastric glands. The proximal intestine had typical small intestinal histological features such as villi. Typical colonic mucosal features were absent as villi were present throughout the intestinal tract. Goblet cells were abundant and increased toward the distal intestine. These intestinal goblet cells contained mostly mixed mucins. Stomach and intestinal content analysis confirmed the presence of arthropod exoskeleton material and possible small vertebrate remnants, commensurate with a low-fibre, protein-rich diet. This may account for their simple GIT morphology, as seen convergently in other unrelated insectivorous mammals. This study provides better representation of variation in GIT morphology among chrysochloridae and within the enigmatic Afrotheria clade. Additionally, it provides a better understanding of the mucin distribution in relation to diet and phylogeny of golden moles.
Many plant–animal interactions can be challenging to directly observe, due to species being small, cryptic and/or nocturnal. Previous research on seed predation and dispersal by rodents in the Fynbos Biome of South Africa has relied on indirect evidence, as methods for directly monitoring rodent–seed interactions were not available. The aims of the study were to determine which resident small mammals scatter-hoard nuts and the geographic, seasonal and taxonomic extent of scatter-hoarding in the Fynbos Biome. We used camera traps focused on seed stations at eight sites in the Fynbos Biome to determine the responses of small mammals to tagged nut-like fruits (nuts) of seven endemic plant species belonging to the Proteaceae (n = 3), Rosaceae (n = 2), Restionaceae (n = 1) and Cupressaceae (n = 1), as well as commercial sunflower seeds. We found Acomys subspinosus and Gerbilliscus paeba scatter-hoarded nuts, which they typically carried and buried individually. Rhabdomys pumilio and Micaelamys namaquensis only consumed nuts. Leucadendron pubescens and L. loranthifolium are added to the list of known plant species that are scatter-hoarded by rodents. Nuts of Cliffortia cuneata and C. phillipsii, and the critically endangered Widdringtonia cedarbergensis, were consumed but not dispersed by small mammals, whereas nuts of Ceratocaryum argenteum were neither consumed nor scatter-hoarded by rodents (within its native range). Gerbilliscus paeba and A. subspinosus scatter-hoarded nuts aseasonally, outside of seed-fall periods. Scatter-hoarding was widespread throughout the Fynbos Biome, although it was highly localised across and within sampled sites. The absence of scatter-hoarding rodents at sites with rodent-dispersed plants remains an important aspect for future investigation.
The Greater Maputaland-Pondoland-Albany (GMPA) region of southern Africa was recently designated as a centre of vertebrate endemism. The phylogeography of the vertebrate taxa occupying this region may provide insights into the evolution of faunal endemism in south-eastern Africa. Here we investigate the phylogeographic patterns of an understudied small mammal species assemblage (Amblysomus) endemic to the GMPA, to test for cryptic diversity within the genus, and to better understand diversification across the region. We sampled specimens from 50 sites across the distributional range of Amblysomus, with emphasis on the widespread A. hottentotus, to analyse geographic patterns of genetic diversity using mitochondrial DNA (mtDNA) and nuclear intron data. Molecular dating was used to elucidate the evolutionary and phylogeographic history of Amblysomus. Our phylogenetic reconstructions show that A. hottentotus comprises several distinct lineages, or evolutionarily significant units (ESUs), some with restricted geographic ranges and thus worthy of conservation attention. Divergence of the major lineages dated to the early Pliocene, with later radiations in the GMPA during the late-Pliocene to early-Pleistocene. Evolutionary diversification within Amblysomus may have been driven by uplift of the Great Escarpment c. 5-3 million years ago (Ma), habitat changes associated with intensification of the east-west rainfall gradient across South Africa and the influence of subsequent global climatic cycles. These drivers possibly facilitated geographic spread of ancestral lineages, local adaptation and vicariant isolation. Our study adds to growing empirical evidence identifying East and southern Africa as cradles of vertebrate diversity.
The large brown, round, strongly scented seeds of Ceratocaryum argenteum (Restionaceae) emit many volatiles found to be present in herbivore dung. These seeds attract dung beetles that roll and bury them. As the seeds are hard and offer no reward to the dung beetles, this is a remarkable example of deception in plant seed dispersal.
Background Golden moles (Chrysochloridae) are small, subterranean, afrotherian mammals from South Africa and neighboring regions. Of the 21 species now recognized, some (e.g., Chrysochloris asiatica , Amblysomus hottentotus ) are relatively common, whereas others (e.g., species of Chrysospalax, Cryptochloris , Neamblysomus ) are rare and endangered. Here, we use a combined analysis of partial sequences of the nuclear GHR gene and morphological characters to derive a phylogeny of species in the family Chrysochloridae. Results Although not all nodes of the combined analysis have high support values, the overall pattern of relationships obtained from different methods of phylogeny reconstruction allow us to make several recommendations regarding the current taxonomy of golden moles. We elevate Huetia to generic status to include the species leucorhinus and confirm the use of the Linnean binomial Carpitalpa arendsi , which belongs within Amblysominae along with Amblysomus and Neamblysomus . A second group, Chrysochlorinae, includes Chrysochloris, Cryptochloris, Huetia, Eremitalpa, Chrysospalax , and Calcochloris . Bayesian methods make chrysochlorines paraphyletic by placing the root within them, coinciding with root positions favored by a majority of randomly-generated outgroup taxa. Maximum Parsimony (MP) places the root either between chrysochlorines and amblysomines (with Chlorotalpa as sister taxon to amblysomines), or at Chlorotalpa , with the former two groups reconstructed as monophyletic in all optimal MP trees. Conclusions The inclusion of additional genetic loci for this clade is important to confirm our taxonomic results and resolve the chrysochlorid root. Nevertheless, our optimal topologies support a division of chrysochlorids into amblysomines and chrysochlorines, with Chlorotalpa intermediate between the two. Furthermore, evolution of the chrysochlorid malleus exhibits homoplasy. The elongate malleus has evolved just once in the Cryptochloris-Chrysochloris group; other changes in shape have occurred at multiple nodes, regardless of how the root is resolved.
Oxygen affinity and other hematological parameters in strictly subterranean mole-rats, Cryptomys hottentotus (subspecies pretoriae) were measured immediately upon capture and after 14-21 days in captivity. The pH, hematocrit, hemoglobin (Hb) concentration, blood oxygen content, 2,3 bisphosphoglycerate (2,3 BPG) concentration and oxygen dissociation curves (ODC), as well as tonometric measurements, were determined using whole blood. Additionally ODCs were also determined for stripped hemolysates of individual animals. Compared to other mammals, blood of freshly caught animals had low pH (7.32 +/- 0.22), elevated hematocrits (48.4 +/- 3.8 %) and significantly lower P-50 values for whole blood (21.1 +/- 1.6 mm Hg at pH 7.4) than those reported for other similar-sized fossorial and terrestrial mammals. Blood carbon dioxide content (22.4 +/- 3.9 mMol L-1), hemoglobin concentration (1.9 +/- 0.15 mMol L-1), oxygen content (164.8 +/- 26 mL L-1), bicarbonate concentrations (22.5 +/- 3.5 mMol L-1) were within the range of values reported for similar-sized mammals. We conclude that high blood-oxygen affinity, low body temperature and possibly also high hematocrit enable C. h. pretoriae to maintain an adequate oxygen supply to the tissues in a potentially hypoxic burrow atmospheres, but that the blood of this species shows no exceptional CO2 sensitivity or buffering capacity. (c) 2006 Elsevier Inc. All rights reserved.
The 2 cryptic species of multimammate mice that occur widely in South Africa were, for many decades, lumped in a single species Mastomys natalensis sensu lato. This taxon was intensively studied because these rodents play a role in the epidemiology of various zoonoses (notably bubonic plague), serve as important models for biomedical research, and also sometimes cause extensive agricultural damage. The discovery that M. natalensis sensu lato includes 2 cryptic species in southern Africa has complicated interpretation of the results of past research because previous studies may have been based on either M. coucha or M. natalensis, or even on specimens of both species. A previous study aimed at craniometrically distinguishing between these species in South Africa met with some success, but excluded subadult specimens (which constitute a large proportion of museum collections), and cautioned that intraspecific variation might hamper interspecific discrimination. We therefore studied the nature and extent of nongeographic craniological variation using 2 populations of each species. The discriminatory value of a putative diagnostic dental character (presence or absence of t3 cusp on M3) is limited because of considerable variation within and among populations of M. coucha. Sexual dimorphism is negligible in both species, whereas age-related variation is pronounced and involves mainly differences in overall size, as well as some subtle differences in the configuration of the interorbital, postpalatal, and dental regions. Multiple discriminant function analyses aimed at craniometrically distinguishing between the 2 species showed that the inclusion of subadult specimens reduced a posteriori classification accuracy below 95% confidence levels, implying that age-related variation is sufficiently pronounced to obscure interspecific craniometric differences. Future studies aimed at craniometrically distinguishing between these cryptic species will, therefore, have to statistically correct for age-related variation.
SUMMARYThe hypertrophied malleus in the middle ear of some golden moles has been assumed to be an adaptation for sensing substrate vibrations by inertial bone conduction, but this has never been conclusively demonstrated. The Cape golden mole (Chrysochloris asiatica) exhibits this anatomical specialization, and the dynamic properties of its middle ear response to vibrations were the subjects of this study.Detailed three-dimensional middle ear anatomy was obtained by x-ray microcomputed tomography (μCT) at a resolution of 12 μm. The ossicular chain exhibits large malleus mass, selective reduction of stiffness and displacement of the center of mass from the suspension points, all favoring low-frequency tuning of the middle ear response. Orientation of the stapes relative to the ossicular chain and the structure of the stapes footplate enable transmission of substrate vibrations arriving from multiple directions to the inner ear.With the long axes of the mallei aligned parallel to the surface, the animal's head was stimulated by a vibration exciter in the vertical and lateral directions over a frequency range from 10 to 600 Hz. The ossicular chain was shown to respond to both vertical and lateral vibrations. Resonant frequencies were found between 71 and 200 Hz and did not differ significantly between the two stimulation directions. Below resonance, the ossicular chain moves in phase with the skull. Near resonance and above, the malleus moves at a significantly larger mean amplitude (5.8±2.8 dB) in response to lateral vs vertical stimuli and is 180° out of phase with the skull in both cases.A concise summary of the propagation characteristics of both seismic body(P-waves) and surface (R-waves) is provided. Potential mechanisms by which the animal might exploit the differential response of the ossicular chain to vertical and lateral excitation are discussed in relation to the properties of surface seismic waves.
Comparison between the middle ear anatomy of the Cape golden mole (Chrysochloris asiatica), which exhibits a club-shaped malleus head, and the Desert golden mole (Eremitalpa granti), with a ball-shaped malleus head, suggests differences in sensitivity to airborne sound. Scanning laser Doppler vibrometric measurements of the ossicular behavior in response to both vibration and airborne sound were made in C. asiatica. Two distinct vibrational modes were observed. In response to low-frequency vibration (70-200 Hz), the malleus oscillates about the ligament of the short process of the incus, whereas in response to high-frequency airborne sound (1-6 kHz) the ossicular chain rotates about the long axis of malleus. It is proposed that the club-shaped malleus head in C. asiatica constitutes an adaptation towards bimodal hearing-sensitivity to substrate vibrations and airborne sound. Possible functional differences between these two middle ear types are discussed.
Golden moles (Chrysochloridae) are poorly known subterranean mammals endemic to Southern Africa that are part of the superordinal clade Afrotheria. Using G-banding and chromosome painting we provide a comprehensive comparison of the karyotypes of five species representing five of the nine recognized genera: Amblysomus hottentotus, Chrysochloris asiatica, Chrysospalax trevelyani, Cryptochloris zyli and Eremitalpa granti. The species are karyotypically highly conserved. In total, only four changes were detected among them. Eremitalpa granti has the most derived karyotype with 2n = 26 and differs from the remaining species (all of whom have 2n = 30) by one centric and one telomere:telomere fusion. In addition, two intrachromosomal rearrangements were detected in A. hottentotus. The painting probes also suggest the presence of a unique satellite DNA family located on chromosomes 11 and 12 of both C. asiatica and C. zyli. This represents a synapomorphy linking these two sympatric species as sister taxa. A molecular clock was calibrated adopting a relaxed Bayesian approach for multigene data sets comprising publicly available sequences derived from five gene fragments representative of three golden moles and 39 other eutherian species. The data suggest that golden moles diverged from a common ancestor approximately 28.5 mya (95% credibility interval = 21.5-36.5 mya). Based on an inferred chrysochlorid ancestral karyotype of 2n = 30, the estimated rate of 0.7 rearrangements per 10 my (95% Credibility Interval = 0.54-0.93) differs from the 'default rate' of mammalian chromosomal evolution which has been estimated at one change per 10 million years, thus placing the Chrysochloridae among the slower-evolving chromosomal lineages thus far recorded.
Insect prey of the Namib golden mole congregate beneath clumps of grass scattered among the sand dunes of the Namib Desert. In the presence of the light winds that typically blow over the Namib Desert, these grass clumps emit low-amplitude vibrations that are transmitted through the sand. While foraging in the sand-swimming mode (a few centimeters below the surface of the sand), some moles apparently were attracted toward manmade sources emitting vibrations matching those recorded from the grass clumps. This is the first direct evidence that these desert mammals use seismic cues for navigation.
The rehabilitation objectives of ash disposal sites associated with coal driven power stations must satisfy the demands of sustainable ecosystems. The rate and success of ash site rehabilitation depends on the sustainability of plant, animal and micro-organism communities in these areas and ecosystem stability is enhanced by habitat and bio- diversity. This paper reports on a study on rehabilitated ash disposal sites to determine the succession of a number of biotic factors along as rehabilitation gradient. These biological parameters include vegetation, soil mesofauna, ants, beetles, and small mammals. The trend in total biodiversity index values shows an initial increase until five years after rehabilitation followed by a gradual decrease. Diversity patterns of the various biotic variables differed greatly, with beetles showing a strong decrease in diversity with age of rehabilitation and ants a significant increase. Succession of assemblages of the biological variables will be discussed. This paper win also report on a modelling attempt using neural network techniques, to determine indicators of rehabilitation success.
Neave’s mouse, Mus neavei (Thomas, 1910), occurs in the Democratic Republic of Congo, Tanzania, Zambia, Mozambique, Zimbabwe and South Africa (Petter 1981; Musser & Carleton 1993), with the latter record based on material from owl pellets taken at Makapansgat (Pocock 1974). Pocock’s record was disputed by Swanepoel et al. (1980), and in the absence of complete voucher specimens, the occurrence of this species in South Africa was regarded as doubtful. However, it was supported by Meester et al. (1986) and accepted by Musser & Carleton (1993).