Hystrix Africaeaustralis Research Articles

Nuclear organization of cholinergic, putative catecholaminergic, serotonergic and orexinergic systems in the brain of the African pygmy mouse (Mus minutoides): Organizational complexity is preserved in small brains

This study investigated the nuclear organization of four immunohistochemically identifiable neural systems (cholinergic, catecholaminergic, serotonergic and orexinergic) within the brain of the African pygmy mouse (Mus minutoides). The African pygmy mice studied had a brain mass of around 275mg, making these the smallest rodent brains to date in which these neural systems have been investigated. In contrast to the assumption that in this small brain there would be fewer subdivisions of these neural systems, we found that all nuclei generally observed for these systems in other rodent brains were also present in the brain of the African pygmy mouse. As with other rodents previously studied in the subfamily Murinae, we observed the presence of cortical cholinergic neurons and a compactly organized locus coeruleus. These two features of these systems have not been observed in the non-Murinae rodents studied to date. Thus, the African pygmy mouse displays what might be considered a typical Murinae brain organization, and despite its small size, the brain does not appear to be any less complexly organized than other rodent brains, even those that are over 100 times larger such as the Cape porcupine brain. The results are consistent with the notion that changes in brain size do not affect the evolution of nuclear organization of complex neural systems. Thus, species belonging to the same order generally have the same number and complement of the subdivisions, or nuclei, of specific neural systems despite differences in brain size, phenotype or time since evolutionary divergence.

Wildlife crop depredation in the Luangwa Valley, eastern Zambia

Wildlife crop raiding was assessed in six chiefdoms of the Luangwa Valley, eastern Zambia between 2004 and 2008 to establish nature and extent of wildlife crop degredation and examine the impact of existing mitigation measures being implemented to deter wildlife crop raiding. Crop damage assessments, involving crop quality, stage of growth and proportion of crop damage, were conducted using six trained field enumerators. Structured questionnaires were administered randomly to local farmers that were inflicted by wildlife crop raiders to elucidate on-farm deterrence measures. Eleven species of wildlife were identified as ‘problem animals’: African elephant (Loxodonta africana), Hippopotamus(Hippopotamus amphibius), Bushpig (Potamochoerus larvatus), Yellow baboon (Papio cynocephalus), Porcupine (Hystrix africaeaustralis), African civet (Civetta civetta), Roan antelope (Hippotragus equinus), Lesser kudu (Tragelaphus strepsiceros), Eland(Taurotragus oryx), Cape buffalo (Syncerus caffer) and Warthog (Phacochoerus africanus). Results showed that African elephant caused the most damage, 67.82 and 98.41% of total wet and dry farming crop raiding incidences respectively, which occurred at crop maturity between February and April. Maize (Zea mays) and cotton (Gossypium hirsutum) were the most affected crops by problem animals, associated with 71.38 and 42.86% of the total crop raids in wet and dry farming seasons respectively. Frequency and extent of damages depended on deterrence measure applied on the crop fields. Of the six chiefdoms, in Malama chiefdom where solar powered electric fences and Capsicum fences were implemented, there were few and less intensive incursions. Based on the findings, we suggest development of capacity for local farmers in effective wildlife crop mitigation measures, particularly against African elephants. Future research would require determining uptake by local farmers and efficacy of novel counter-measures. Key words: Wildlife crop raiding, conservation, Luangwa Valley

Development of primers to amplify mitochondrial DNA control region of Old World porcupines (subgenus Hystrix)

Eight primers were developed for the amplification of mitochondrial DNA control region of Old world porcupines (subgenus Hystrix). Successful amplifications of low-quality DNA extracted from old (12years old) and recent quills were performed, thus facilitating field sampling. Successful cross-species amplifications were obtained for Hystrix africaeaustralis, H. cristata and H. indica. Length and structure of mitochondrial DNA control region were analysed and its usefulness as genetic marker for interspecific and population investigation was discussed.

Nuclear organization and morphology of cholinergic, putative catecholaminergic and serotonergic neurons in the brain of the Cape porcupine ( Hystrix africaeaustralis): Increased brain size does not lead to increased organizational complexity

The distribution, morphology and nuclear organization of the cholinergic, putative catecholaminergic and serotonergic systems within the brain of the Cape porcupine ( Hystrix africaeaustralis) were identified following immunohistochemistry for choline acetyltransferase, tyrosine hydroxylase and serotonin. The aim of the present study was to investigate possible differences in the complement of nuclear subdivisions of these systems in the Cape porcupine in comparison with previous studies of these systems in other rodents. The Cape porcupine is the largest rodent in which these systems have been examined and has an adult body mass of 10–24 kg and an average brain mass of approximately 37 g, around 15 times larger than the laboratory rat. The Cape porcupines were taken from the wild and while these differences, especially that of mass, may lead to the prediction of a significant difference in the nuclear organization or number within these systems, all the nuclei observed in all three systems in the laboratory rat and in other rodents had direct homologues in the brain of the Cape porcupine. Moreover, there were no additional nuclei in the brain of the Cape porcupine that are not found in the laboratory rat or other rodents studied and vice versa. It is noted that the medial septal nucleus of the Cape porcupine appeared qualitatively to have a reduced number of neurons in comparison to the laboratory rat and other rodents. The locus coeruleus of the laboratory rat differs in location to that observed for the Cape porcupine and several other rodent species. The Cape porcupine is distantly related to the laboratory rat, but still a member of the order Rodentia; thus, changes in the organization of these systems appears to demonstrate a form of constraint related to the phylogenetic level of the order.

Density of Cape porcupines in a semi-arid environment and their impact on soil turnover and related ecosystem processes

Cape porcupines ( Hystrix africaeaustralis) appear to have an important influence on landscapes through both biotic (foraging) and abiotic (soil turnover) impacts. Porcupine abundance and abiotic effects across the landscape were investigated in Nieuwoudtville, South Africa, a semi-arid area characterized by an extraordinary diversity and abundance of geophytes. Porcupine numbers were measured in 50 burrows, and the number of burrow entrances was a good predictor of the number of porcupines it contained ( r 2=0.76). Occupied burrow density was estimated to be 2.6 burrows km −2 and porcupine density on the study farm was estimated to be 8 animals km −2, which is high relative to other Hystrix populations in semi-arid environments. This can probably be attributed to the high abundance of geophytes in the region. Annually, porcupines disturb 0.34% of the soil surface and 1.6 m 3 ha −1 yr −1 of soil is displaced across the landscape, through the excavation of 160–3463 diggings per hectare. Up to 2.2 m 3 of soil is displaced per hectare per year in the natural Dolerite Plains vegetation, but very little foraging activity occurs in previously or currently ploughed lands. The extent of disturbance in Nieuwoudtville is on a par with or higher than that recorded for other porcupine populations in arid or semi-arid regions. Other studies have shown that porcupine diggings disturb plant community structure and create fertile sites for plant germination and recruitment. Porcupine diggings in Nieuwoudtville contained significantly more seedlings than adjacent areas. Thus, through widespread foraging pits, soil turnover, and numerous burrows, porcupines modulate the availability of resources to other organisms. Therefore, Cape porcupines are likely to act as ecosystem engineers in this landscape. Porcupines should be included in any conservation actions involving the unique geophyte flora of Nieuwoudtville.

40Ar/39Ar dating in the Lochaber–Mulgrave area, northern mainland Nova Scotia: implications for timing of regional metamorphism and sediment provenance in the Late Devonian – Early Carboniferous Horton Group

40Ar/39Ar dating of whole-rock samples and muscovite separates using age spectrum analysis, and of single muscovite grains using total fusion analysis, yields new insights into the timing of regional metamorphism and sediment provenance in the Late Devonian – Early Carboniferous Horton Group in the Lochaber–Mulgrave area of Nova Scotia. The time of regional metamorphism is constrained to ca. 340–335 Ma by whole-rock spectra from well-cleaved slate and shale samples from the lowermost Clam Harbour River and overlying Tracadie Road formations of the Horton Group. This ca. 340–335 Ma event may have been the result of burial and deformation of the Horton Group by older volcanic and sedimentary rocks of the Guysborough Group, which were overthrust from the south as the result of development of a positive flower structure at a restraining bend along the Cobequid–Chedabucto fault system, the boundary between the Meguma and Avalon terranes. Detrital muscovite ages of ca. 410–380 and ca. 500 Ma were obtained from single-grain analysis and from spectral analysis of separated grains. Whole-rock spectra for two samples from a mylonitic metasedimentary unit in the Cape Porcupine Complex yielded plateau ages of 364 ± 4 and 367 ± 4 Ma, providing a likely source for ca. 370–360 Ma detrital muscovite, ages that may be reflected in some of the age spectrum data. However, the Meguma terrane to the south is the most likely source for most of the detrital muscovite.

AN ECOLOGICAL PERSPECTIVE OF REPRODUCTION IN THE CAPE PORCUPINE

SUMMARY Cape porcupines Hystrix africaeaustralis occur throughout southern Africa and their resistance and resilience to disturbances is ascribed to the response of reproductive mechanisms to perturbations. In the Cape porcupine physical contact between the sexes maintains cyclic ovarian activity and pair-bonding. Group formation and maintenance are a prerequisite for conception, and only one female in a group reproduces. However, porcupine females do have the ability to compensate for the loss of litters by conceiving within a few days of such loss. Dispersal of young from their natal colonies is a prerequisite for reproduction. Such dispersal, stimulated by the artificial reduction in density, may give rise to a decrease in the age of first reproduction and thus an increase in population growth rate in response to disturbance.

Social organization and space use in the Cape porcupine in a Southern African savanna

SummarySix male and four female adult Cape porcupines (Hystrix africaeaustralis) were radiotracked between July 1989 and June 1990 in a southern African savanna in order to investigate their social organization and space‐use patterns. They lived in family groups based upon monogamous adult pairs. Pair members shared burrows and home range areas and all pairs were stable for the duration of the study. It is suggested that the occurrence of family groups is largely dependent on the opportunities available for mature offspring to disperse from their natal group. Individual home ranges occupied the same general location throughout the year although the exact area used varied from month to month and most activity was concentrated in a relatively small portion of a potentially larger area. Natural foragers had significantly larger home ranges in winter than in summer. Crop foragers exhibited no significant seasonal difference in range size.Home range overlap between natural foraging neighbours was greatest in winter but even then was not extensive, there being little overlap between neighbouring 95% and 90% home ranges. It is therefore suggested that porcupines are territorial, maintaining a small, exclusive territory within a larger, non‐exclusive home range. Neighbours rarely encountered one another in the areas of overlap and territories were probably maintained by scent marking rather than through direct interactions.RésuméDes porcs‐épics du Cap (Hystrix africaeaustralis), six mâles et quatre femelles adultes, ont été suivis par radiotracking entre juillet 1989 et juin 1990 dans une savane sud‐africaine pour étudier leur organisation sociale et le schéma de leur utilisation du territoire. Ils vivaient en groupes familiaux basés sur une paire d'adultes monogames. Les membres du couple partagaient le même terrier et le même espace vital, et tous les couples sont restés stables jusqu'à la fin de la recherche. On suggère que l'existence de groupes familiaux dépend largement des possibilités dont dispose la descendance mature de se disperser à l'écart du groupe d'origine. Les espaces vitaux respectifs occupaient globalement le même territoire tout au long de l'année même si l'endroit précis variait de mois en mois et que la plus grande partie de leur activité se déployait dans une portion relativement resteinte d'un espace potentiellement plus étendu. Ceux qui se nourrissaient en nature disposaient d'un territoire significativement plus vaste en hiver qu'en été alors que ceux qui se nourrissaient sur les cultures ne présentaient pas de différence significative dans ce domaine.Le recouvrement des espaces vitaux des animaux qui se nourrissaient en nature était plus important en hiver qu'en été, mais même alors il n'était pas très grand, car il y avait peu de recouvrement entre 90 à 95% des espaces vitaux avoisinants. C'est pourquoi on suggère que les porcs‐épics sont territoriaux, et conservent un petit territoire exclusif inclus dans un espace vital plus étendu mais non exclusif. Les voisins se rencontrent rarement dans les endroits de recouvrement, et les territoires sont probablement gardés au moyen de marques olfactives plutôt que par des interactions directes.

The effect of premature weaning on reproductive output of female Cape porcupines Hystrix africaeaustralis

The effect of premature weaning on reproductive output of female Cape porcupines <i>Hystrix africaeaustralis</i>

Purification and characterization of progesterone-binding globulin in the pregnant Cape porcupine, Hystrix africaeaustralis

Progesterone-binding globulin (PBG) was purified from pooled pregnant Cape porcupine ( Hystrix africaeaustralis) plasma by SP-Sephadex Chromatography, followed by Sephacryl S-200 gel filtration. The final product was homogeneous according to high performance capillary electrophoresis, SDS-polyacrylamide gel electrophoresis and sedimentation equilibrium centrifugation. A molecular mass of 65,300 Da was calculated from sedimentation equilibrium centrifugation data. Scatchard analysis indicated a dissociation constant of 0.82 × 10 −9M, and PBG concentration of 18.4 nmole/mg protein.

Concentrations of plasma total and unbound progesterone and testosterone during pregnancy in Cape porcupines, Hystrix africaeaustralis

Total plasma and unbound progesterone and testosterone concentrations in pregnant Cape porcupines were determined by radioimmunoassay and centrifugal ultrafiltration dialysis of plasma collected at weekly intervals throughout gestation. During pregnancy, total plasma progesterone and testosterone concentrations attained values of up to ~200ng/ml and ~2000pg/ml, respectively. However, unbound progesterone and testosterone remained relatively constant at 2% and 13% of total values, respectively. The low concentrations of unbound steroids result from high concentrations of plasma binding proteins which probably protect progesterone and testosterone from metabolism during pregnancy. High testosterone concentrations may induce the production of plasma progesterone binding proteins during pregnancy to maintain high progesterone concentrations.

Habitat utilization by the Cape porcupine Hystrix africaeaustralis in a savanna ecosystem

Habitat utilization on three scales by Cape porcupines (Hystrix africaeaustralis) was investigated in a savanna ecosystem at Nylsvley Nature Reserve in the northern Transvaal, South Africa.On the macroscale, radiotelemetry indicated that porcupines preferred broad‐leaf Burkea savanna to Acacia savanna. The individual variation in macroscale habitat preferences indicates that porcupines may be constrained in their use of habitats by territoriality.On the intermediate scale, no specific feeding areas within the home ranges of porcupines could be identified by using overlapping radiotelemetry circles.On the microscale, observations of two leash‐walked porcupines indicated that feeding patches are not randomly located but correspond to the distribution of certain plant species important in the diet of porcupines. Patches may be identified or protected by means of scent‐marking.

Aspects of habitat disturbance by Cape porcupines in a savanna ecosystem

Habitat disturbances by Cape porcupines (Hystrix africae- australis) in a savanna ecosystem were investigated at Nylsvley Nature Reserve by using transect line surveys for signs of porcupine foraging activities. The density of foraging diggings was significantly higher in Burkea savanna than in Acacia savanna. A significantly higher proportion of trees was debarked in Burkea and rocky outcrop savanna than in Acacia savanna. The only two species which were preferentially debarked were dominant species in the former two habitat types. Significantly more trees had roots gnawed on by porcupines in Burkea savanna than elsewhere, and the species most affected (Burkea africana) was a dominant species in this habitat type. Concentrated feeding activities in Burkea and rocky outcrop savanna by porcupines may affect the structure of these plant communities.

Properties of proteins binding plasma progesterone in pregnant Cape porcupines (Hystrix africaeaustralis).

The properties of progesterone-binding proteins in plasma of pregnant Cape porcupines were investigated using radiolabelled progesterone and either progesterone or cortisol as competing ligands as well as native plasma and heated (60 degrees C for 30 min) plasma. The results demonstrated that plasma from pregnant porcupines contains corticosteroid-binding globulin, but that it constitutes a significant portion of plasma progesterone-binding proteins only during the early stages of pregnancy. Corticosteroid-binding globulin of porcupines appears to be as heat labile as that of guinea-pigs. Concentrations of progesterone-binding proteins in plasma increased during pregnancy to reach concentrations at the eleventh week that were 25 times higher than those of progesterone; concentrations increased significantly (r2 = 0.88) with the increase in progesterone concentration. The results indicate that plasma progesterone-binding proteins in Cape porcupines (Old World hystricomorph) are similar in composition to those in guinea-pigs (New World hystricomorph).

Burrowing and huddling in newborn porcupine: The effect on thermoregulation

The newborn cape porcupine Hystrix africaeaustralis is a precocial rodent. However, the newborn spends its first 9 weeks in the burrow. Heat production (oxygen consumption— V ̇ O 2 ) and body temperature ( T b) were measured at various ambient temperatures ( T a) in newborn (4–8-week-old) porcupines, with a body mass between 1340–1993 g during summer, from the colony kept at the Mammal Research Institute, University of Pretoria. To assess the effect of huddling, these parameters were also measured in adult pairs of porcupines ( T a = 15 and 25°C) kept together in the metabolic chamber and the values were compared with those obtained from single porcupines. Overall minimal thermal conductance was calculated for newborn and paired adult porcupines. The newborn porcupines can regulate their body temperature at T as between 10–28°C. V ̇ O 2 measured at lower critical point is 0.602 ± 0.08 ml/O 2/g · h. At T a = 10°C, V ̇ O 2 oscillated with a characteristic amplitude and frequency, while body temperature was well regulated. Huddling decreases the lower critical point. The overall minimal thermal conductance (0.044 ± 0.002 ml O 2/g · h · 1°C) is higher than expected from body mass, so that the young are liable to lose heat rapidly. It is well known that the newborn porcupine spends a long period in the burrow and the results of this study suggest that this may be in order to conserve energy and presumably allocate it to growth. Apart from decreasing vulnerability, delaying foraging also avoids heat loss in the newborn porcupine.

URINARY CHARACTERISTICS OF THE CAPE PORCUPINE HYSTRIX AFRICAEAUSTRALIS: EFFECTS OF PHOTOPERIOD AND TEMPERATURE

The Cape porcupine Hystrix africaeaustralis is a large (11-18 kg), nocturnal, burrowing and group-living rodent. It experiences a metabolic response to seasonal acclimatization and is a hind gut fermenter. Changes in the urinary electrolyte and free urinary catecholamine concentrations of Cape porcupines were related to combined changes of ambient temperature and photoperiod regime. Three groups, A) Ta = 25 degrees C, 12L:12D; B) Ta = 32 degrees C, 16L:8D; C) Ta = 10 degrees C, 8L:16D, were studied to assess the influence of seasonal acclimatization on urinary bicarbonate and catecholamine concentrations. Urine volume was significantly (p < 0.001) higher in group C than in the other two groups. In groups B and C urinary pH was above 7 and this was associated with high concentrations of HCO3-. The total amount of catecholamines was higher in groups B and C than in group A. It is apparent that seasonal acclimatization of the Cape porcupine is also reflected by these parameters.

Reproductive inhibition in the Cape porcupine, Hystrix africaeaustralis

Sexually mature female Cape porcupines kept under natural conditions of illumination and temperature did not conceive while housed within their natal groups. Before removal from their natal groups the sexually mature offspring copulated and experienced cyclic ovarian activity, but conception occurred only 70-120 days after dispersal. Mean oestrous cycle length of these females (36.9 +/- 11.5 days; n = 34) was similar to that of breeding females (33.0 +/- 11.64 days; n = 16), but mean peak plasma progesterone concentration (6.45 +/- 6.03 ng/ml; n = 34) was significantly (P less than 0.01) lower than that of cyclic breeding females (13.58 +/- 6.98 ng/ml; n = 16). Mean progesterone concentration at oestrus in non-breeding females (0.72 +/- 0.45 ng/ml; n = 34) was also significantly (P less than 0.01) lower than that of non-pregnant breeding females (4.21 +/- 2.44 ng/ml; n = 16). Reproductive inhibition within natal groups, in which only one female reproduces, therefore cannot be ascribed to a failure to copulate, but may be due to some factor inhibiting full expression of luteal activity or affecting ovulation.

The stimulation of testosterone and LH secretion by synthetic GnRH in the male Cape porcupine

The effects of GnRH stimulation on plasma testosterone and luteinizing hormone (LH) levels in Cape porcupine males were examined by analysing plasma collected before and after an intravenous injection of GnRH. In six mature males and one subadult, which were given an intravenous injection of 0,5 ml saline, levels of plasma testosterone and LH did not increase. Four weeks later an intravenous GnRH challenge (40 μg) caused plasma testosterone to rise three-fold and LH to rise 10-15-fold within 180 min in five of the mature males. Peaks of plasma testosterone and LH occurred 90 and 120 min, respectively, after stimulation, and baseline and peak levels of both hormones were significantly related.

Metabolism and Thermoregulation in the Cape Porcupine,Hystrix africaeaustralis

Oxygen consumption (V̇o2) and body temperature (Tb) were measured at various ambient temperatures (Ta) between 13° and 39° C in individuals of the Cape porcupine (Hystrix africaeaustralis), acclimated to Ta = 25° C at a controlled photoperiod of 12L:12D. V̇o2 of this species in the thermoneutral zone (Ta = 24°–27° C) is only 5796 of the V̇o2 of an 11.1 ± 0.7 kg mammal aspredicted by Kleiber. Tb was well regulated up to Ta = 30° C. Hyperthermia was observed at Ta above 30° C. Tb regulation was accompanied by an increase in overall thermal conductance and respiratory frequency rate. Overall minimal thermal conductance calculated at lower critical point Ta = 24° C is higher than predicted by Bradley and Deavers. Apparently digestible dry-matter intake and gross digestible energy intake are relatively low and correlate with the low V̇o2 values recordedfor this species. Water intake in this species is significantly lower than that of the crested porcupine (H. indica) under similar conditions. Low metabolic rates on the one hand and high overall thermal conductance on the other appear to be importantphysiological adaptations for this large, burrowing, nocturnal rodent, which has a wide ecological tolerance.

Metabolic rates, food consumption and thermoregulation in seasonal acclimatization of the Cape porcupine Hystrix africaeaustralis

Metabolic rates by means of oxygen consumption (VO(2)) at various ambient temperatures (T (a)) and food consumption as well as water intake and thermoregulation were compared between individuals of the Cape porcupine Hystrix africaeaustralis acclimated to T (a)=32°C with a photoperiod of 16L:8D summer-acclimated and T (a)=10°C; 8L:16D winter-acclimated. The lower critical temperature as well as overall minimal thermal conductance were lower for the winter-acclimated porcupines when compared to summer-acclimated ones, while VO(2) at the thermoneutral-zone was significantly (P<0.001) higher in the winter-acclimated porcupines. Dry matter intake, apparent digestible dry matter intake, gross digestible energy intake, as well as water intake, were significantly higher in the winter-acclimated porcupines. Yet, while dry matter intake increased 4 times in the winter-acclimated porcupines, apparent digestible dry matter increased only at a rate of 2.9 times. This difference is better reflected in terms of digestibility efficiency which in the winter-acclimated porcupines is only at a rate of 67.5% while in the summer-acclimated porcupines it is at a rate of 90%. From the results of this study, it is possible to assume that heat production in the winter-acclimated porcupines is partly increased by food intake. Increased heat production on the one hand, and a decrease in overall minimal thermal conductance on the other, seem to be important mechanisms in winter acclimatization of the Cape porcupine.