Macroscelides Proboscideus Research Articles

Specifically unspecific – Simple devices as feasible and effective enrichment for small mammals

Although enrichment is an essential part of modern zoo animal husbandry, research on effective enrichment for small mammals is scarce, albeit they are regularly kept in zoos. To develop solutions that are inexpensive, readily applicable, and adaptable for a variety of species, we investigate whether three types of simple enrichment devices (SEDs) – object, olfactory, and food-motivated – elicit positive interactions in various zoo-housed small mammal species. In this preliminary exploration study, we evaluate if amount of enrichment interactions, display of behavioral stress reactions, and display of stereotypic behaviors vary, if different types of SEDs are provided. Therefore, we observed 39 individuals of ten species, most of which are underrepresented in enrichment literature: Eastern quoll (Dasyurus viverrinus), round-eared elephant shrew (Macroscelides proboscideus), aardvark (Orycteropus afer), southern tamandua (Tamandua tetradactyla), northern Luzon giant cloud rat (Phloeomys pallidus), green acouchi (Myoprocta pratti), South African springhare (Pedetes capensis), aye-aye (Daubentonia madagascariensis), golden lion tamarin (Leontopithecus rosalia), and Javan mouse-deer (Tragulus javanicus) housed in Frankfurt Zoo, Germany. All focal individuals interacted with at least two types of SEDs and around 80% interacted with all types of SEDs, resulting in a considerable amount of time spent with the enrichment. There was a preference for food-motivated enrichment. Neither behavioral stress reactions nor stereotypic behaviors differed if different types of SEDs were present. Model selection showed that GLMs explaining enrichment interactions improved if the variable ‘individual’ instead of ‘species’ was included, suggesting that reactions towards unspecific SEDs might be more individual-driven than species-specific. Because individuals of all species chose to interact with the SEDs and we did not find behavioral indicators for stress elicited by the SEDs, we advocate for the regular provision of SEDs for small mammals in human care.

Redescription of Maupasina weissi (Seurat, 1913) (Nematoda: Ascaridida) from sengis, Elephantulus spp. and Macroscelides proboscideus (Shaw) (Macroscelidea), in Africa.

Maupasina weissi (Seurat, 1913), is redescribed from the eastern rock sengi, Elephantulus myurus Thomas & Schwann, from Limpopo Province and compared with material collected from Free State and North West Provinces, South Africa, as well as the description of the type-material from South Tunisia. Distinguishing features of the species include a corona radiata of 12 pointed leaflike elements, a complex bipartite buccal capsule with 3 large bicuspid denticular lobes and 4 smaller club-shaped lobes and 11 (occasionally 10) pairs of cloacal papillae in the male. The complex taxonomic history of the genus Maupasina Seurat, 1917 is discussed. The probable misidentification of Macroscelides proboscideus Shaw, the short eared sengi, from North West Province, South Africa, as a host of M. weissi is explained, indicating that M. weissi occurs only in species of the genus Elephantulus Thomas & Schwann. The widely separated geographical regions, stretching the length of the African continent, in which M. weissi has been found are indicative of a conservative species with a broad geographical distribution. Tenebrionid beetles, up to 50% of stomach contents of E. myurus in Limpopo Province may act as intermediate hosts in the life-cycle of M. weissi.

Comparative anatomy of neonates of the three major mammalian groups (monotremes, marsupials, placentals) and implications for the ancestral mammalian neonate morphotype.

The existing different modes of reproduction in monotremes, marsupials and placentals are the main source for our current understanding of the origin and evolution of the mammalian reproduction. The reproductive strategies and, in particular, the maturity states of the neonates differ remarkably between the three groups. Monotremes, for example, are the only extant mammals that lay eggs and incubate them for the last third of their embryonic development. In contrast, marsupials and placentals are viviparous and rely on intra-uterine development of the neonates via choriovitelline (mainly marsupials) and chorioallantoic (mainly placentals) placentae. The maturity of a newborn is closely linked to the parental care strategy once the neonate is born. The varying developmental degrees of neonates are the main focus of this study. Monotremes and marsupials produce highly altricial and nearly embryonic offspring. Placental mammals always give birth to more developed newborns with the widest range from altricial to precocial. The ability of a newborn to survive and grow in the environment it was born in depends highly on the degree of maturation of vital organs at the time of birth. Here, the anatomy of four neonates of the three major extant mammalian groups is compared. The basis for this study is histological and ultrastructural serial sections of a hatchling of Ornithorhynchus anatinus (Monotremata), and neonates of Monodelphis domestica (Marsupialia), Mesocricetus auratus (altricial Placentalia) and Macroscelides proboscideus (precocial Placentalia). Special attention was given to the developmental stages of the organs skin, lung, liver and kidney, which are considered crucial for the maintenance of vital functions. The state of the organs of newborn monotremes and marsupials are found to be able to support a minimum of vital functions outside the uterus. They are sufficient to survive, but without capacities for additional energetic challenges. The organs of the altricial placental neonate are further developed, able to support the maintenance of vital functions and short-term metabolic increase. The precocial placental newborn shows the most advanced state of organ development, to allow the maintenance of vital functions, stable thermoregulation and high energetic performance. The ancestral condition of a mammalian neonate is interpreted to be similar to the state of organ development found in the newborns of marsupials and monotremes. In comparison, the newborns of altricial and precocial placentals are derived from the ancestral state to a more mature developmental degree associated with advanced organ systems.

Home range and use of diurnal shelters by the Etendeka round-eared sengi, a newly discovered Namibian endemic desert mammal.

To understand habitat use by the newly described Etendeka round-eared sengi (Macroscelides micus) in northwestern Namibia, we radio-tracked five individuals for nearly a month. Home ranges (100% convex polygons) in the rocky desert habitat were remarkably large (mean 14.9 ha) when compared to sengi species in more mesic habitats (<1.5 ha). The activity pattern of M. micus was strictly nocturnal, which contrasts to the normal diurnal or crepuscular activity of other sengis. The day shelters of M. micus were under single rocks and they likely were occupied by single sengis. One tagged sengi used 22 different day shelters during the study. On average, only 7% of the day shelters were used more than once by the five tagged sengis. The shelters were also unusual for a small mammal in that they were unmodified in terms of excavation or nesting material. Shelter entrances were significantly oriented to face south by south west (average 193°), away from the angle of the prevailing midday sun. This suggests that solar radiation is probably an important aspect of M. micus thermal ecology, similar to other sengis. Compared to published data on other sengis, M. micus generally conforms to the unique sengi adaptive syndrome, but with modifications related to its hyper-arid habitat.

A new species of round-eared sengi (genusMacroscelides) from Namibia

While studying the systematics and taxonomy of round-eared sengis (genus Macroscelides), we identified an unusual specimen from remote northwestern Namibia in the collection of the California Academy of Sciences. To determine if this represented a different species, we made 9 collecting trips with 5,616 trap-nights of effort that produced 16 voucher specimens (including the original specimen) of the unusual sengi. These specimens are distinguished from other Macroscelides species by morphological metrics (they are smaller), external features (rusty-tinged pelage, large subcaudal gland, and lack of dark skin pigment), and by divergence at 3 independently segregating DNA loci. These traits are the basis for the description of a new species of Macroscelides that seems to be confined to gravel plains associated with the distinctive reddish colored Etendeka geological formation of northwestern Namibia. The new species appears to be reproductively isolated from congeners, because portions of its distribution are sympatric with that of the Namib round-eared sengi (M. flavicaudatus), and we found no evidence of hybrid individuals or gene flow. The new species is allopatric with the Karoo round-eared sengi (M. proboscideus), which is found about 500 km to the south. The new species, along with M. flavicaudatus, is endemic to Namibia. With this 3rd species in the genus, there are now 19 recognized extant species in the order Macroscelidea.

Effects of livestock grazing and habitat characteristics on small mammal communities in the Knersvlakte, South Africa

We studied the influence of different livestock grazing intensities and habitat types on small mammals in the Knersvlakte, South Africa. The Knersvlakte belongs to the Succulent Karoo Biome, a biodiversity hotspot. We placed a total of 22 plots in areas of two grazing intensities (moderate and intensive) and two major habitat types (quartz fields and loamy soils). On these plots, we carried out small-mammal live trapping (90 traps during four nights) and estimated the cover of different vegetation layers. In total, 140 small mammal individuals from ten species were caught during 7920 trap nights. All species occurred on loamy soils, but only four in quartz fields. The small-mammal community on intensively-grazed plots was a subset of that on moderately-grazed plots. The most abundant species on loamy soils were Macroscelides proboscideus and Rhabdomys pumilio and in quartz fields M. proboscideus and Gerbillurus paeba. Generalised linear models revealed that habitat type had the strongest influence on abundance and diversity of small mammals. Vegetation cover mainly had indirect influences, via the habitat type, on abundance, diversity and the body condition of small mammals. Overall, the intensities of livestock grazing showed no effect on abundance and diversity.

Petrosal and Bony Labyrinth Morphology Supports Paraphyly of Elephantulus Within Macroscelididae (Mammalia, Afrotheria)

Interest in the phylogeny of Macroscelididae (sengis or elephant shrews) has been prompted by molecular studies indicating that Elephantulus rozeti is best placed as the sister group of Petrodromus tetradactylus (this clade being in turn the sister taxon to Macroscelides proboscideus) than among other species of the genus Elephantulus. Until now, no discrete morphological characters have been proposed to support the grouping of E. rozeti, Petrodromus, and Macroscelides into this single so-called ‘Panelephantulus’ clade. Here, we employed μCT scanning in order to investigate the petrosal and bony labyrinth (bony capsule of the inner ear) morphology of most species of extant Macroscelididae. We performed a cladistic analysis on ear traits and found that despite some convergences (e.g., concerning the bony arterial canals in Macroscelides and Rhynchocyon) the middle and inner ear morphology furnishes significant support for the ‘Panelephantulus’ clade. In our analysis, this clade is unambigously supported by the presence of a fully ossified stapediofacial tube. Two additional characters (the presence of a bony septum at the mouth of the fenestra cochleae dividing the D3 sinus into two distinct cavities and the absence of an accessory lateral pneumatic fossa) could also support ‘Panelephantulus.’ These newly discovered morphological characters support the molecular phylogenies published and highlight the importance of coding hitherto difficult to sample morphologies within cladistic analyses using micro-CT techniques. Taxonomic implications are briefly discussed.

Promiscuous tendencies in the round-eared sengi: a male’s perspective

Although monogamy is interpreted as risk-adverse strategy by reducing intra-sexual conflicts, most pair-living males increase their reproductive success by engaging in extra-pair copulations. However, little is known about costs involved in such extra-pair attempts from the male’s perspective. We investigated promiscuous tendencies of paired Macroscelides proboscideus (round-eared elephant-shrew or round-eared sengi), a pair-living small mammal occurring in southern Africa. In particular, we measured potential costs of extra-pair attempts for the males. For this, we conducted laboratory experiments, involving interactions between neighbouring male–female pairs. Data collection included direct behavioural observations and establishing the morphological and physiological characteristics of males. Both sexes intruded into the neighbouring area, and initiated sexual behaviour with neighbours of the opposite sex. Males which displayed a higher marking frequency in the neighbouring area received more sexually motivated behaviour from neighbouring females. Resident males attacked intruding males. Aggression experienced by and marking behaviour of intruding males was positively correlated with body mass losses. Furthermore, glucocorticoid levels, determined from analyses of faeces and urine samples, correlated positively with body mass losses and marking behaviour of intruding males, indicating costs of intruding. We conclude that male as well as female round-eared sengis have promiscuous tendencies. Although interactions with neighbouring females may offer potential benefits for males in terms of enhanced reproductive success, males also seem to pay substantial costs, as indicated by body mass losses and elevated stress hormone levels.

Relative importance of habitat connectivity in shaping the genetic profiles of two southern African elephant‐shrews

AbstractAim When interpreting genetic patterns across a landscape it is surprisingly difficult to disentangle the effects of landscape connectivity from those of species biology. Here, the spatial distributions of genetic variation of two sympatric elephant‐shrew species, the western rock elephant‐shrew (Elephantulus rupestris) and the round‐eared elephant‐shrew (Macroscelides proboscideus), are determined and compared. We selected these species because they have similar biologies but differ markedly in habitat use, the rationale being that differences in their genetic structure should be a result largely of landscape variables directly or indirectly affecting dispersal rather than of the biology of the species.Location South Africa and Namibia.Methods Mitochondrial sequence data (control region and cytochrome b) were used to describe the phylogeographic structure of these elephant‐shrew species across their distribution. To determine whether genetic variation is significantly structured, spatial analyses of molecular variation were performed. Isolation‐by‐distance versus alternative patterns of genetic structure was investigated using a Mantel test.Results Our analyses indicated an overall structured genetic profile for E. rupestris, a species closely associated with rocky outcrops. This was in contrast to a pattern mostly of isolation‐by‐distance across the distribution of M. proboscideus, a species found on gravel plains.Main conclusions Specific landscape features will differentially affect gene flow (both historical and current), and therefore also the spatial genetic structure, of species with markedly different habitat requirements. The genetic profiles for the two species included here support predictions based on the connectivity of their respective occupied habitats. The results also support the more general prediction that species with a naturally clustered distribution (such as E. rupestris) should have a more structured genetic pattern than those having a more continuous distribution (M. proboscideus).

Host-specific germination of the root holoparasite Hydnora triceps (Hydnoraceae)

We provide the first germination data on the root-holoparasitic Hydnoraceae. Aqueous root extracts of host and non-host Euphorbia spp. were applied to seeds of Hydnora triceps Drège &amp; Meyer, a narrow endemic of Namibia and South Africa. The seeds of H. triceps germinated only in response to root extracts of its exclusive host, Euphorbia dregeana Meyer, and not for co-occurring non-host Euphorbia spp. This pattern of host specific germination suggests that germination response to host-root cues may be responsible for host partitioning. Provenance of H. triceps seeds and E. dregeana root extracts did not significantly affect germination rates. The round-eared elephant shrew ( Macroscelides proboscideus ) and the striped mouse ( Rhabdomys pumilio ) were observed feeding on the fleshy pulp of H. triceps fruits. Small-mammal droppings collected from the same partially consumed fruits contained intact seeds (1.9 ± 1.1 seeds/dropping) providing indirect evidence of seed dispersal by small mammals.

The Round‐Eared Sengi and the Evolution of Social Monogamy: Factors that Constrain Males to Live with a Single Female

AbstractAnimal dispersion in space and time results from environmental pressures, and affects the outcome of a species’ social organization. When females are solitary, males may either roam or be pair‐living. We studied possible environmental influences affecting the social organization of the round‐eared sengi (Macroscelides proboscideus) in a semi‐desert in South Africa, using trapping and radio‐tracking across 2.5 yr. Adult sex ratios did not deviate from 1:1 and we found no indication of sexual dimorphism in body mass. Females maintained exclusive areas, which had little overlap (&lt;4%) with neighbouring females (NF), and males overlapped predominately only with the home range of single females. Generally, inter‐ and intra‐sexual overlap with neighbouring individuals was low (3–6%) for both sexes, indicating territoriality and pair‐living. Pairs were perennial and territories were maintained year‐round. However, males generally maintained much larger areas than females, which were sensitive to population density. Male space use appeared to be primarily limited by the presence of neighbouring males. Female home ranges were smaller‐sized despite changes in population density, possibly for energetic efficiency. Some paired males attempted to take over widowed females, but shifted back to their original home range following the intrusion of an un‐paired male. We conclude that social monogamy is the predominant social organization in round‐eared sengis in a semi‐desert that may have resulted from females living solitarily in small exclusive territories, balanced sex ratios, and from a low variation of body mass between males.

Male mate guarding in a socially monogamous mammal, the round-eared sengi: on costs and trade-offs

Mate guarding is predicted to be one of the driving forces for the evolution of monogamy, but supporting evidence in free-living mammals is rare. The goals of our study were three-pronged. First, we tested if mate guarding, measured as intrapair distance, occurs as a behavioral tactic in round-eared sengis (Macroscelides proboscideus), a socially monogamous species lacking paternal care and in which females breed asynchronously, producing 2–3 litters during an 8-month long breeding season. Second, we determined if mate guarding involves costs which we identified as changes in male body mass. Third, we investigated whether variation in individual investment in mate guarding depended on the males’ body mass and the number of neighboring males. Field data were collected in a semidesert in South Africa using radio-tracking, trapping, and direct observations during three successive breeding seasons. Mate guarding strongly depended on the females’ reproductive state, and all males started to guard their mates prior to and during estrus, as exemplified by reduced intrapair distance. Mate guarding incurred costs: overall, males lost about 5% of body mass. Male body mass loss and initial body mass were negatively related to the intensity of precopulatory mate guarding. Furthermore, during estrus intrapair distance was inversely correlated with the number of neighboring males. The results show that mate guarding is the predominant male tactic in round-eared sengis. However, since mate guarding imposed costs, males may balance benefits and costs associated with guarding by varying their effort in relation to their physical capabilities and the competitive environment.

Dental Ontogeny in Macroscelides proboscideus (Afrotheria) and Erinaceus europaeus (Lipotyphla)

We investigated the state of dental eruption in specimens of Macroscelides proboscideus and Erinaceus europaeus of known age. When M. proboscideus reaches adult size and sexual maturity, few or none of its replaced permanent cheek teeth have erupted. The approximate sequence of upper tooth eruption is P1, [I3, C, M1], [I1–2], M2, P4, [P2, P3]. Chronologically, E. europaeus erupts its molars and most premolars prior to M. proboscideus; but its first two upper incisors erupt after those of M. proboscideus, and its canines erupt around the same time. The approximate sequence of upper tooth eruption in E. europaeus is [M1, M2, P2, I3], C, M3, P4, P3, I2, I1. Unlike M. proboscideus, E. europaeus does not reach adult size until all permanent teeth except for the anterior incisors have erupted. While not unique among mammals, the attainment of adult body size prior to complete eruption of the permanent cheek teeth is particularly common among macroscelidids and other afrotherians.

Confirmation of pleisiomorphic daily torpor in mammals: the round-eared elephant shrew Macroscelides proboscideus (Macroscelidea).

The characteristics of daily torpor were measured in the round-eared elephant shrew Macroscelides proboscideus (Macroscelidea) in response to ambient temperature and food deprivation. Elephant shrews are an ancient mammal order within a superordinal African clade including hyraxes, elephants, dugongs and the aardvark. M. proboscideus only employed torpor when deprived of food; torpor did not occur under an ad libitum diet at ambient temperatures of 10, 15 and 25 degrees C. Torpor bout duration ranged from < 1 h to ca. 18 h. The times of entry into torpor were restricted to the scotophase, despite normothermic body temperature patterns indicating a rest phase coincident with the photophase. Full arousal was always achieved within the first 3 h of the photophase. When food deprived, the onset of the rest phase, and hence torpor, advanced with respect to the experimental photoperiod. The lowest torpor body temperature measured was 9.41 degrees C. Daily torpor in M. proboscideus confirms a pleisiomorphic origin of daily heterothermy. Torpor facilitates risk-averse foraging behaviour in these small omnivores by overcoming long-term energy shortfalls generated by the inherent variability of food availability in their semiarid, El Niño-afflicted habitats.

Reproduction in the round‐eared elephant shrew ( Macroscelides proboscideus ) in the southern Karoo, South Africa

Reproduction in round-eared elephant shrews occurred throughout the year. Male round-eared elephant shrews were spermatogenically active, with spermatozoa stored in the cauda epididymes, throughout the year. Pregnant females occurred in all months except March and May and there was a decline in the occurrence of pregnancies during early winter (March-July). This tendency towards seasonality of pregnancies was mirrored by the appearance of juveniles, with 77% of all young animals caught between September and February. Bone calcium concentrations were significantly lower during the dry winter than during summer. From October onwards (the beginning of the wet season), bone calcium concentrations increased, reaching high levels in December which were maintained until April. This increase in bone calcium concentrations coincided with the rainy season and with an increase in the intake of herbage, and during this period 60% of all pregnancies occurred. We conclude that the ability of the round-eared elephant shrew to vary its diet may allow some individuals to breed throughout the year. The reduction in the occurrence of pregnancies in early winter probably ensures that few births occur when bone calcium concentrations are low.

Risk-sensitive foraging behaviour of the round-eared elephant shrew ( Macroscelides proboscideus )

Risk-sensitive foraging behaviour of the round-eared elephant shrew ( Macroscelides proboscideus )

Risk-sensitive foraging behaviour of the round-eared elephant shrew (Macroscelides proboscideus)

We examined the risk-sensitive foraging behaviour of the round-eared elephant shrew by open-economy choice experiments, in which animals were deprived of food immediately prior to experiments but given food ad libitum afterwards, to test the energy budget rule. The energy budget rule states that if an animal's (daily) energy budget is negative it should behave in a risk-prone manner. A risk-prone elephant shrew should select food from a more variable rather than a constant feeding station, although both feeding stations yield the same average return. The choice of a variable station can indicate the degree to which an animal is an energy-shortfall minimizer. Elephant shrews running below energy requirement did not choose feeding stations in accordance with the rule. Under laboratory conditions, approximating either average summer or winter temperatures, elephant shrews showed risk-averse behaviour. A polycyclic activity profile, the ability to switch the diet, and greater than expected physiological control over energy balance, may favour a continuously foraging animal such that short-term energy deficits are minimized. We argue that, under these conditions, a risk-averse response to reward-size variance is expected, because an elephant-shrew may not reliably perceive those circumstances under which risk-prone behaviour should be adopted.

The Round‐eared Elephant‐Shrew Macroscelides proboscideus (Macroscelidea) as an omnivore

ABSTRACTElephant‐shrews were classified as Insectivora and were traditionally considered to be insectivorous, although ancestral forms were herbivorous. Despite the presence of a functional caecum, many authors still describe elephant‐shrews as insectivorous. Three data sets, totalling 143 samples, of the Round‐eared Elephant‐Shrew Macroscelides proboscideus diet from the semi‐arid Karoo, South Africa, were analysed. Results indicate that this species is largely insectivorous, although plant matter makes up almost 45% of the diet by volume. Diet varies seasonally, with the intake of herbage peaking in winter, when herbage may comprise up to 97% of the diet The contribution of insects to the diet was not related to either insect availability (as indexed by pit‐trapping) or body condition, suggesting that Round‐eared Elephant‐Shrews may be true omnivores, selecting a diet of both insects and herbage. The relatively long large intestine of this species of elephant‐shrew may not be related to the water requirements, but may be a plesiomorphic character that has been retained as a consequence of the higher degree of omnivory displayed by Round‐eared Elephant‐Shrews, which appear to consume more plant matter than the other elephant‐shrews.

The digestive tract ofMacroscelides proboscideusand the effects of diet quality on gut dimensions

The digestive anatomy of the round-eared elephant shrew, Macroscelides proboscideus, was investigated. The gut combines features indicative of both insectivory and herbivory. The stomach is a unilocular glandular sac. The caecum is an elongate blind-ending pouch, and houses a diverse microflora. The colon is well developed (25% of gut length). Digestive anatomy supports Kerley's (1995) contention that M. proboscideus is a true omnivore. The gut dimensions of M. proboscideus responded to differences in food quality, animals fed a high fibre diet exhibiting greater caecal capacity than those fed a low fibre diet. This hindgut plasticity is likely to compensate for short-term changes in food quality,

Temperature regulation and activity pattern of the round-eared elephant shrew Macroscelides proboscideus

1. 1. Oxygen consumption ( V O 2), thermal conductance ( C), body temperature ( T b) and evaporative water loss (EWL) of Macroscelides proboscideus were measured at air temperatures from 5 to 38°C. 2. 2. The lowest V O 2 was approximately that predicted for a eutherian of equal body weight. Minimal C was higher than predicted. EWL was high for an arid adapted small mammal. T bs were stable between 10 to 25°C but increased above 30°C. 3. 3. Captive elephant shrew activity was predominantly nocturnal, although animals were active both day and night. 4. 4. Temperature regulation does not show the usual trends found in arid adapted small mammals.