Black-backed jackals (Canis mesomelas) from semi-arid rangelands in South Africa harbour Hepatozoon canis and a Theileria species but apparently not Babesia rossi.

Despite the importance of disease as a wildlife management challenge in South Africa, baseline data on the epidemiology of pathogens occurring in free-ranging species has received little attention to date. Black-backed jackals (Canis mesomelas) are a wide-ranging, abundant carnivore with substantial economic importance due to their role in livestock depredation. They are known reservoirs hosts of Babesia rossi, a virulent pathogen in domestic dogs in sub-Saharan Africa. We investigated the prevalence and diversity of tick-borne pathogens (TPBs) including Babesia, Theileria, Hepatozoon, Ehrlichia and Anaplasma species, together with host-attached tick diversity, in a black-backed jackal population from the semi-arid Central Karoo, a small-livestock farming region in South Africa. Using reverse line blot hybridisation, we screened 43 blood samples and sequenced the 18S rRNA gene from positive samples to confirm and characterise pathogen identity using a phylogenetic framework. Hepatozoon canis, a ubiquitous pathogen of domestic and wild canids globally, was observed in 47% of jackals, while a Theileria sp. most similar to T. ovis, a piroplasm found in small livestock, was observed in 5% of jackals. No Babesia, Ehrlichia or Anaplasma species were identified, although a Sarcocystis sp. sequence was isolated from one jackal. Host-attached ticks (n = 20) comprised three species, Amblyomma marmoreum, Haemaphysalis elliptica/zumpti and Ixodes rubicundus, commonly known ticks in the region. In summary, prevalence of TBPs in black-backed jackals from this semi-arid rangeland region was lower than in jackal populations in more mesic regions. These jackals were apparently not infected with B. rossi. While this study is one of the first investigations into the epidemiology of TBPs infecting jackals and adds to the sparse literature, further studies which span landscape uses, climate conditions and seasonality are encouraged.

Nonlethal management of baboons on the urban edge of a large metropole.

The transformation of natural land for agricultural and urban use has displaced baboons from large parts of their historical distribution. Abundant resources within transformed areas, however, continue to attract baboons back into these human-dominated areas resulting in chronic levels of conflict throughout much of Africa. In the city of Cape Town, chacma baboons (Papio ursinus) have been raiding human-derived foods for over 200 years. In the last 20 years, the management of this conflict has shifted from predominantly lethal to nonlethal methods. In this study, we assess the success of field rangers to deter baboons from urban areas and investigate whether such management affects the diet and activity patterns of baboons. We opportunistically sampled baboon behavior and movement when field rangers were temporarily absent from managed troops in 2008. We also compared the intensity of baboon management by comparing one troop on days when the field rangers aggressively herded the troop away from the urban edge versus passively monitored them in 2004/2005. Our results reveal that when field rangers were absent, the two troops spent 70% and 80% of their time within the urban edge compared to 3% and 19% when they were present. Both troops also consumed more human-derived foods when field rangers were absent. There was no significant change in the activity budget or daily distance traveled for either troop with and without field rangers. The intensity of herding did have an impact on baboon activity and high levels of herding significantly reduced time spent feeding and increased time spent traveling, socializing, and resting. Habitat use and dietary composition did not differ between high- and low-herding days. Our results suggest that field rangers are a successful nonlethal method for reducing spatial overlap between baboons and urban areas but that intensive, unsystematic herding of the troop does have measurable impacts on behavior and should be prevented.

The effects of extreme seasonality of climate and day length on the activity budget and diet of semi-commensal chacma baboons (Papio ursinus) in the Cape Peninsula of South Africa.

We examined the effects of extreme seasonality on the activity budget and diet of wild chacma baboons with access to a high-quality, human-derived food source. The Cape Peninsula of South Africa is unusual among nonhuman primate habitats due to its seasonal extremes in day length and climate. Winter days are markedly shorter and colder than summer days but have higher rainfall and higher primary production of annually flowering plants. This combination of fewer daylight hours but higher rainfall is substantially different from the ecological constraints faced by both equatorial baboon populations and those living in temperate climates with summer rainfall. We sought to understand how these seasonal differences affect time budgets of food-enhanced troops in comparison to both other food-enhanced troops and wild foraging troops at similar latitudes. Our results revealed significant seasonal differences in activity budget and diet, a finding that contrasts with other baboon populations with access to high-return anthropogenic foods. Similar to nonprovisioned troops at similar latitudes, troop members spent more time feeding, socializing, and traveling during the long summer days compared to the short winter days, and proportionately more time feeding and less time resting in summer compared to winter. Summer diets consisted mainly of fynbos and nonindigenous foods, whereas winter diets were dominated by annually flowering plants (mainly grasses) and ostrich pellets raided from a nearby ostrich farm. In this case, food enhancement may have effectively exaggerated seasonal differences in activity budgets by providing access to a high-return food (ostrich pellets) that was spatially and temporally coincident with abundant winter fallback foods (grasses). The frequent use of both alien vegetation and high-return, human-derived foods highlights the dietary flexibility of baboons as a key element of their overall success in rapidly transforming environments such as the South African Cape Peninsula.

The colonic groove or furrow: a comparative morphological study of six species of African mole-rats (Rodentia, Bathyergidae).

Herbivorous mammals such as nutrias, guinea pigs, chinchillas, and mole-rats have a longitudinal mucosal colonic groove (furrow) in their ascending colon, which is thought to play a role in the colonic separation mechanism (CSM). It is not known whether this groove is structurally modified to adapt to this function in mole-rat species. The morphology of this groove was studied in 32 mol-rats, four species, one of which consisted of three subspecies, endemic to southern Africa and two species found in eastern Africa. The macroscopic morphology of the groove was documented, and samples for histological examination were taken. The groove was wide at its origin at the cecocolic junction and was lined on either side by a row of papillae with the opposing papillae slightly offset in arrangement. The papillated groove gradually decreased in size toward the distal part of the ascending colon where it disappeared. This pattern was similar in all species except in Heterocephalus glaber, where the papillae were absent and the groove was lined by two longitudinal ridges. A histological examination of cross sections revealed that the mucosa covering the inner and outer walls of the groove was rich in mucous-secreting goblet cells. The walls of the groove contained smooth muscle extending from the inner circular smooth muscle layer at the base to the tips of the papillae in all species examined as well as arteries, lymphatic vessels, and prominent sinusoid-like veins. The groove could be demonstrated both macroscopically and histologically in three Bathyergus suillus fetuses of varying sizes. The sinusoid-like veins present in all grooves, regardless of macroscopic shape, suggest that they have a role in the functioning of the groove.

The topography and gross anatomy of the gastrointestinal tract of the Cape dune mole-rat (Bathyergus suillus).

The Cape dune mole-rat, Bathyergus suillus, is the largest truly subterranean rodent in the world and is restricted to sandy soil areas of the southern and South-western Cape Province. These animals are herbivorous, feeding mostly on the below ground portions of grass and geophytes. The present study was undertaken to explore whether there are any gross anatomical gastrointestinal adaptations associated with the herbivorous diet of the Cape dune mole-rat and to provide a basis for further investigations into the nutrition and ecology of this animal. The stomach was unilocular (simple) and the entire internal aspect displayed macroscopically visible glandular epithelium. The caecum was voluminous and arranged into a spiral of approximately one and a half turns. The tip of the caecum resembled a vermiform appendix and lay against the left lateral abdominal wall. The ascending colon consisted of proximal and distal portions, arranged in a large double loop and attached to each other by a fat-filled mesenteric fold. The looped, folded ascending colon filled the right side of the abdominal cavity, lying against the right dorsal, lateral and ventral abdominal wall. The internal structure of the ascending colon revealed a shallow groove, lined on either side by a row of papillae. The simple, glandular stomach in conjunction with a prominent caecum and a greatly enlarged ascending colon suggests that this animal is a hindgut fermenting herbivore, rather than a caecal fermenter, as is the case in most rodent species.

Cooperation, control, and concession in meerkat groups.

"Limited control" models of reproductive skew in cooperative societies suggest that the frequency of breeding by subordinates is determined by the outcome of power struggles with dominants. In contrast, "optimal skew" models suggest that dominants have full control of subordinate reproduction and allow subordinates to breed only when this serves to retain subordinates' assistance with rearing dominants' own litters. The results of our 7-year field study of cooperative meerkats, Suricata suricatta, support the predictions of limited control models and provide no indication that dominant females grant reproductive concessions to subordinates to retain their assistance with future breeding attempts.

Morphological castes in a vertebrate.

Morphological specialization for a specific role has, until now, been assumed to be restricted to social invertebrates. Herein we show that complete physical dimorphism has evolved between reproductives and helpers in the eusocial naked mole-rat. Dimorphism is a consequence of the lumbar vertebrae lengthening after the onset of reproduction in females. This is the only known example of morphological castes in a vertebrate and is distinct from continuous size variation between breeders and helpers in other species of cooperatively breeding vertebrates. The evolution of castes in a mammal and insects represents a striking example of convergent evolution for enhanced fecundity in societies characterized by high reproductive skew. Similarities in the selective environment between naked mole-rats and eusocial insect species highlight the selective conditions under which queen/worker castes are predicted to evolve in animal societies.

Individual contributions to babysitting in a cooperative mongoose, Suricata suricatta.

Evolutionary explanations of cooperative breeding based on kin selection have predicted that the individual contributions made by different helpers to rearing young should be correlated with their degree of kinship to the litter or brood they are raising. In the cooperative mongoose or meerkat, Suricata suricatta, helpers babysit pups at the natal burrow for the first month of pup life and frequent babysitters suffer substantial weight losses over the period of babysitting. Large differences in contributions exist between helpers, which are correlated with their age, sex and weight but not with their kinship to the young they are raising. Provision of food to some group members raises the contributions of individuals to babysitting. We discuss the implications of these results for evolutionary explanations of cooperative behaviour.

Selfish sentinels in cooperative mammals.

Like humans engaged in risky activities, group members of some animal societies take turns acting as sentinels. Explanations of the evolution of sentinel behavior have frequently relied on kin selection or reciprocal altruism, but recent models suggest that guarding may be an individual's optimal activity once its stomach is full if no other animal is on guard. This paper provides support for this last explanation by showing that, in groups of meerkats (Suricata suricatta), animals guard from safe sites, and solitary individuals as well as group members spend part of their time on guard. Though individuals seldom take successive guarding bouts, there is no regular rota, and the provision of food increases contributions to guarding and reduces the latency between bouts by the same individual.

Infanticide and expulsion of females in a cooperative mammal.

In cooperative groups of suricates (Suricata suricatta), helpers of both sexes assist breeding adults in defending and feeding pups, and survival rises in larger groups. Despite this, dominant breeding females expel subordinate females from the group in the latter half of their (own) pregnancy apparently because adult females sometimes kill their pups. Some of the females that have been expelled are allowed to rejoin the group soon after the dominant female's pups are born and subsequently assist in rearing the pups. Female helpers initially resist expulsion and repeatedly attempt to return to their natal group, indicating that it is unlikely that dominant females need to grant them reproductive concessions to retain them in the group.

A dispersive morph in the naked mole-rat.

Close inbreeding is known for a variety of small mammal species for which a high probability of mortality during dispersal makes helping and delayed maturation a relatively secure fitness option. Prolonged inbreeding, however, is usually associated with lowered fitness, and it has been shown that most highly inbred small mammals and social insects have inbreeding-avoidance mechanisms that promote some degree of outbreeding. However, previous field and laboratory research on the naked mole-rat (Heterocephalus glaber) suggested that this cooperatively breeding rodent is highly inbred, with new colonies forming by fission. Here we report the discovery of a dispersal phenotype that may occasionally promote outbreeding in naked mole-rats. These dispersers are morphologically, physiologically and behaviourally distinct from other colony members. They are laden with fat, exhibit elevated levels of luteinizing hormone, have a strong urge to disperse, and only solicit matings with non-colony members. These findings suggest that, although rare, a dispersive morph exists within naked mole-rat colonies.

Mammalian eusociality: a family affair.

Comparative studies of two species of mole-rat are helping to clarify the ecological correlates of mammalian eusociality. Both species live in social groups composed of close kin, within which breeding is restricted to one female and one to three males. They inhabit xeric areas with dispersed, patchy food and unpredictable rainfall. During droughts, they can neither expand their tunnel systems nor disperse. In brief periods after rain the animals must cooperate and dig furiously to locate rich food patches. By living in groups, arid-zone mole-rats can take full advantage of windows of opportunity when conditions are right for burrowing. Thus, ecological factors and kin selection have apparently interacted in the evolution of eusociality in these species.