Phylogeography and conservation of impala and greater kudu

The phylogeography of the bush habituated African bovid species impala (Aepyceros melampus) and greater kudu (Tragelaphus strepsiceros) is investigated using mitochondrial DNA (mtDNA) markers. Combined analysis of individual lineages, relationships and population genetics suggest a colonization process from Southern Africa toward Eastern regions in the greater kudu. Results are less clear for the impala, although remaining consistent with a similar pattern of historical dispersion. The study reveals a similar pattern, that is a marked divergence of lineages from South-western Africa relative to other regions. This pattern is opposed to previously published findings in other African bovid species. In the impala, the genetically isolated region is consistent with morphology because it is recognized as the subspecies A. m. petersi, the black-faced impala. In contrast, the similar split of South-western mitochondrial lineages was not expected in the greater kudu on the basis of morphology. Both species show a significant population genetic differentiation. Beyond their phylogeographical value, our results should raise conservation concerns about South-western populations of both species. The black-faced impala is categorized as vulnerable and our data show indications of hybridization with common impala A. m. melampus. The previously unrecognized genetic status of the South-western kudus could also imply conservation regulations.     

Distinguishing dung from blue, red and yellow-backed duikers through noninvasive genetic techniques

Dung counts have been widely used to estimate duiker abundance and densities in tropical African forests. However, one of the major limitations of this method is that species' identification of dung based on morphological characteristics is extremely difficult in most cases. Some authors made the assumption that dung pellets could at least be distinguishable between the blue duiker, the red duikers and the yellow-backed duiker. However, this study is the first attempt to test the reliability of field identification. In this study, we suggest a method based on a noninvasive genetic protocol to identify duiker species. The comparison of field and genetic identifications shows that only dung from Cephalophus silvicultor was identified in the field without error. The rate of error for red duikers and the blue duiker is high and any attempt to distinguish among those species will result in wrong estimations for each species. We recommend the use of DNA tests to ensure reliable species' identification when duiker censuses based on dung counts are used. This methodological input will probably strengthen the dung count technique and increase its reliability for duiker species abundance estimations and spatial distribution studies.     

The genetic status of naturally occurring black-nosed impala from northern South Africa

The impala (Aepyceros melampus ssp.) is a widespread antelope species occurring in sub-Saharan Africa. The two recognized subspecies have non-overlapping distribution ranges, with no known natural mixture of these subspecies until human interference. A number of common impala individuals (A. m. melampus) displaying phenotypic characteristics commonly observed in the black-faced impala (A. m. petersi), namely black facial markings, were seen on a farm in the Limpopo Province, South Africa. This farm falls outside the natural distribution range of A. m. petersi. We therefore aimed to identify the taxonomic placement of these individuals (i.e. A. m. melampus or A. m. petersi) through phylogenetic and molecular clock analyses using D-loop and cytochrome subunit b sequence data. Our results showed that these black-nosed impala from Limpopo are in fact A. m. melampus individuals. The existence of the black-nose phenotype in common impala could be more widespread than previously estimated. The occurrence of introgression between the two subspecies in this region could, however, not be fully excluded, and can only be fully assessed through the use of nuclear DNA analysis.     

Morphometry of implantation in sheep. I. Trophoblast attachment, modification of the uterine lining, conceptus size and embryo location

The degree of trophoblastic attachment, modification of the uterine lining epithelium during implantation, possible differences in size of the conceptus, and preferential zones of nidation were evaluated. Eight ewes at 14 (n=3), 17 (n=2), 20 (n=1), and 24 (n=2) d of gestation were used, and 6 to 8 equidistant samples of either uterine o uterine plus embryonic membranes tissues were taken from each uterine horn for histomorphometric analysis. Trophoblastic attachment varied from 1.5 to 100% at 14 and 24 d of gestation, respectively. Modification of the uterine lining epithelium ranged from 0% at 14 d to 90% at 24 d. The conceptuses occupied a variable area of the uterine cavity; 15.1% at 14 d, 100% at 17 d, 70.6% at 20 d and 100% at 24 d of gestation. All the embryos were located caudal to the center of the uterine horn. Attachment of the trophoblast and modification of the uterine lining epithelium occurred in the area surrounding the embryos. Implantation was a gradual and long-lasting process which commenced near the embryo and extended peripherally. Morphological variations need to be considered when evaluating embryonic viability.     

Model highlights likely long‐term influences of mesobrowsers versus those of elephants on woodland dynamics

The potential long‐term influences of mesobrowsers versus those of savannah elephants on woodland dynamics have not been explored. This may be a critical omission especially in southern African savannahs, where efforts to preserve existing woodlands are typically directed at elephant management. We describe a simple browse–browser model, parameterized from an extensive review of the literature and our own data, including quantitative assessment of impala impact, from the study site, iMfolozi Park, South Africa. As there is a paucity of species‐specific demographic data on savannah woody species, we modelled, in a novel approach, functional groups of plant species typical of Acacia woodlands. Outputs suggest that over the long term (100 years), low‐to‐moderate densities of impala will have a similar impact on woodland structure, in terms of density of adult trees, as low‐to‐moderate densities of elephant. Further, the outputs highlight the apparently strong synergistic effect impala and elephant impacts combined have on woodland dynamics, suggesting that reduction or removal of either impala or elephant will radically reduce long‐term destruction of savannah woodlands. Recorded changes in adult tree numbers in iMfolozi broadly supported the model's outputs.     

Differential response of seven duiker species to human activities in Taï National Park,Côte d'Ivoire

African rainforest is severely impacted by human activities, ranging from resource collection, selective logging to fragmentation and scale deforestation. Consequently, large mammal communities occurring therein are strongly modified. Here, we present a study conducted in Taï National Park (TNP), which characterises the spatial distribution and differential response of seven duiker species to human activities. Based on extensive survey data recorded between 2005 and 2015, we used a maximum entropy modelling approach for predicting duiker species distribution and a hierarchical clustering approach to identify potential subgroups in the duiker community. The seven duiker species clearly differed in their spatial distribution, with Cephalophus dorsalis and Philantomba maxwellii being the most common and widely distributed with no clear response towards gradients of impact from human activities. In contrast, Cephalophus ogilbyi, Cephalophus jentinki, Cephalophus sylvicultor and Cephalophus zebra showed increasing responses towards anthropogenic impact gradients, with the latter two being particularly sensitive. These duikers are not found in areas of illegal human activities. The restricted distribution of Cephalophus niger seems artificial and may indicate species misidentification. The strong spatial signature of human activities in the duiker community of TNP is of concern. Effective park management, including extensive ranger patrols, is vital for ensuring the persistence of this unique duiker community in West Africa.     

Chorionic gonadotrophin and embryo-maternal recognition during the peri-implantation period in primates

Genes for chorionic gonadotrophin (CG) are transcribed by the 16-cell embryo stage in humans, but there is no clear evidence of CG secretion as a bioactive dimer before attachment and trophoblast outgrowth stages of implantation. The studies summarized question the timing of CG expression and secretion, the possible roles of CG for intraembryonic differentiation and at the implantation site, and the recognition of this primate embryo-derived signal in support of the corpus luteum. The data suggest that the implantation window in primates may be broader than in non-primate species, where a closer synchrony between embryonic, tubal and uterine events appears to be necessary for embryonic survival. Some preliminary data concerning an association between peripheral thrombocytopenia, ovarian inhibin secretion and peri-implantation stages of embryo development indicate that an unknown embryonic signal may be secreted before bioactive CG can be detected.     

Genetic structure of the common impala (Aepyceros melampus melampus) in South Africa: phylogeography and implications for conservation

We analysed 131 common impala (Aepyceros melampus melampus) samples from two provinces in South Africa (Limpopo and KwaZulu‐Natal) that are separated by the Drakensberg Mountain Range using sequences of the mitochondrial control region and seven polymorphic nuclear microsatellite loci. In line with earlier studies on bovid species, we found very high values of genetic diversity, particularly at the mtDNA locus with an overall nucleotide diversity of 3.6% and an overall haplotype diversity of 0.98. All statistical approaches confirmed a significant population differentiation between Limpopo and KwaZulu‐Natal, suggesting that areas of unsuitable habitat caused by the presence of the Drakensberg Range and the Indian Ocean coastal belt act as a barrier to gene flow. Only few individuals with signs of admixed origin were indicative of translocations or rare migration between the two provinces. Combination of our mtDNA data set with those of previous studies on impala from south‐western, southern and eastern Africa revealed the highest diversity in South Africa. This is in line with the hypothesis of a southern glacial refuge from which various African ungulate species spread northeast during the Holocene, although in the case of impala further analyses based on larger data sets will be necessary to definitively settle this question.     

Co-existence and niche segregation of three small bovid species in southern Mozambique

Niche segregation among three small antelopes – red duiker, common duiker and suni – was investigated in a coastal savanna woodland/forest mosaic. It was expected that these similar‐sized concentrate selectors would show differentiation in diet choice to decrease competition. Diet composition did not vary significantly among the different vegetation types. For all three antelope species, the number of dietary items was large, with a minimum of 70 different food items per species. Dietary specialization was low, with only 10% of the food items being exclusively used by each of the species. The ranks of food items were positively correlated among species in the wet season, but not in the dry season. Diet breadth significantly decreased in the dry season. The use of exclusive species was significantly larger in the dry season with lowest values recorded for the common duiker. Diet overlap in the wet season was considerable, but significantly decreased in the dry season, the time of food scarcity. The dry season data showed evidence for niche segregation, although this was not based on displacement. As niche segregation in the dry season was coupled to a random apportionment of diet items among antelope species, it cannot be interpreted as the result of competitive displacement.     

Regional genetic structuring and evolutionary history of the impala Aepyceros melampus

Samples of 162 impala antelope (Aepyceros melampus) from throughout its distribution range in sub-Saharan Africa were surveyed using eight polymorphic microsatellite loci. Furthermore, 155 previously published mitochondrial DNA (mtDNA) sequences from the same localities were reanalyzed. Two subspecies of impala are presently recognized--the isolated black-faced impala (Aepyceros melampus petersi) in southwest Africa and the common impala (Aepyceros melampus melampus) abundant in southern and east Africa. All tests performed indicated significant genetic differentiation at the subspecific level. Furthermore, individual-based analyses split the common impala subspecies into two distinct genetic groups, conforming with regional geographic affiliation to southern or east Africa. This was supported by assignment tests, genetic distance measures, pairwise theta values, and analysis of molecular variance. We suggest that the presence of such previously unknown regional structuring within the subspecies reflects a pattern of colonization from a formerly large panmictic population in southern Africa toward east Africa. This scenario was supported by a progressive decline in population diversity indices toward east Africa and a significant increase in the quantity theta/(1 - theta). Both microsatellite and mtDNA data indicated a genetic distinctiveness of the Samburu population in Kenya.     

Uterine receptivity and the plasma membrane transformation

This review begins with a brief commentary on the diversity of placentation mechanisms, and then goes on to examine the extensive alterations which occur in the plasma membrane of uterine epithelial cells during early pregnancy across species. Ultrastructural, biochemical and more general morphological data reveal that strikingly common phenomena occur in this plasma membrane during early pregnancy despite the diversity of placental types--from epitheliochorial to hemochorial, which ultimately form in different species. To encapsulate the concept that common morphological and molecular alterations occur across species, that they are found basolaterally as well as apically, and that moreover they are an ongoing process during much of early pregnancy, not just an event at the time attachment, the term ‘plasma membrane transformation‘ is suggested which also emphasises that alterations in this plasma membrane during early pregnancy are key to uterine receptivity.     

Seasonal diet changes in elephant and impala in mopane woodland

Elephant and impala as intermediate feeders, having a mixed diet of grass and browse, respond to seasonal fluctuations of forage quality by changing their diet composition. We tested the hypotheses that (1) the decrease in forage quality is accompanied by a change in diet from more monocots in the wet season to more dicots in the dry season and that that change is more pronounced and faster in impala than in elephant; (2) mopane (Colophospermum mopane), the most abundant dicot species, is the most important species in the elephant diet in mopane woodland, whereas impala feed relatively less on mopane due to the high condensed tannin concentration; and (3) impala on nutrient-rich soils have a diet consisting of more grass and change later to diet of more browse than impala on nutrient-poor soils. The phosphorus content and in vitro digestibility of monocots decreased and the NDF content increased significantly towards the end of the wet season, whereas in dicots no significant trend could be detected. We argue that this decreasing monocot quality caused elephant and impala to consume more dicots in the dry season. Elephant changed their diet gradually over a 16-week period from 70% to 25% monocots, whereas impala changed diets rapidly (2?C4?weeks) from 95% to 70% monocots. For both elephants and impala, there was a positive correlation between percentage of monocots and dicots in the diet and the in vitro digestibility of these forage items. Mopane was the most important dicot species in the elephant diet and its contribution to the diet increased significantly in the dry season, whereas impala selected other dicot species. On nutrient-rich gabbroic soils, impala ate significantly more monocots than impala from nutrient-poor granitic soils, which was related to the higher in vitro digestibility of the monocots on gabbroic soil. Digestibility of food items appears to be an important determinant of diet change from the wet to the dry season in impala and elephants.     

Prey preferences of the leopard (Panthera pardus)

Leopards Panthera pardus have a catholic diet and are generally thought to prey on medium-sized ungulates; however, knowledge on which species are actually preferred and avoided is lacking, along with an understanding of why such preferences arise. Twenty-nine published and four unpublished studies of leopard diet that had relative prey abundance estimates associated with them were analysed from 13 countries in 41 different spatial locations or temporal periods throughout the distribution of the leopard. A Jacobs' index value was calculated for each prey species in each study and the mean of these was then tested against a mean of 0 using t or sign tests for preference or avoidance. Leopards preferentially prey upon species within a weight range of 10–40 kg. Regression plots suggest that the most preferred mass of leopard prey is 25 kg, whereas the mean body mass of significantly preferred prey is 23 kg. Leopards prefer prey within this body mass range, which occur in small herds, in dense habitat and afford the hunter minimal risk of injury during capture. Consequently, impala, bushbuck and common duiker are significantly preferred, with chital likely to also be preferred with a larger sample size from Asian sites. Species outside the preferred weight range are generally avoided, as are species that are restricted to open vegetation or that have sufficient anti-predator strategies. The ratio of mean leopard body mass with that of their preferred prey is less than 1 and may be a reflection of their solitary hunting strategy. This model will allow us to predict the diet of leopards in areas where dietary information is lacking, also providing information to assist wildlife managers and conservation bodies on predator carrying capacity and predator–prey interactions.     

Transposon impala, a novel tool for gene tagging in the rice blast fungus Magnaporthe grisea

impala, a Tc1-mariner transposable element from Fusarium oxysporum, was introduced into the rice blast fungus Magnaporthe grisea to develop transposon-based insertional mutagenesis. A construct (pNIL160) containing an autonomous impala copy inserted in the promoter of niaD encoding Aspergillus nidulans nitrate reductase was introduced by transformation into a M. grisea nitrate reductase-deficient mutant. impala excision was monitored by restoration of prototrophy for nitrate. Southern analysis of niaD+ revertants revealed that impala was able to excise and reinsert at new loci in M. grisea. As observed for its host Fusarium oxysporum, impala inserted at a TA site left a typical excision footprint of 5 bp. We have shown that a defective impala copy was inactive in M. grisea, yet it can be activated by a functional impala transposase. A transformant carrying a single copy of pNIL160 was used to generate a collection of 350 revertants. Mutants either altered for their mycelial growth (Rev2) or nonpathogenic (Rev77) were obtained. Complementation of Rev77 with a 3-kb genomic fragment from a wild-type locus was successful, demonstrating the tagging of a pathogenicity gene by impala. This gene, called ORP1, is essential for penetration of host leaves by M. grisea and has no sequence homology to known genes.     

The significance of chicory to the diet of common duiker at Grants valley, Eastern Cape Province, South Africa

South Africa is considered one of the top four chicory (Chichorium intybus) producing countries of the world and commercial growing of the plant in the country is restricted to a small area in three districts of the Eastern Cape Province. Faecal analysis technique was used to study the diet of common duiker (Sylvicapra grimmia Linnaeus, 1758) in a chicory growing region at Grants valley. One of the principal items in the diet of these antelopes was chicory and the crop provided more than one third (35.6%) of the winter diet and a substantial proportion (14.4%) of the spring diet of common duiker. These findings confirmed earlier reports of common duiker feeding on cultivated crops and may have profound implications for the South African chicory industry. The study also confirmed earlier findings that common duiker are selective feeders and predominantly browsers, consuming only a very small proportion of monocotyledonous plants.     

No suggestion of hybridization between the vulnerable black-faced impala (Aepyceros melampus petersi) and the common impala (A. m. melampus) in Etosha National Park, Namibia

There are two recognized subspecies of impala in sub-Saharan Africa: the common impala (Aepyceros melampus melampus) -- widespread in southern and east Africa -- and the vulnerable black-faced impala (A. m. petersi) -- found naturally in only a small enclave in southwest Africa. The Etosha National Park (NP) in Namibia harbours the largest and only protected-area population of black-faced impala, numbering some 1500 individuals. Due to translocations of the exotic common impala to commercial farms in Namibia during the past decades, the black-faced impala in Etosha is faced with the potentially serious threat of hybridization posed by secondary contact with the common impala inhabiting bordering farms. Using eight microsatellite DNA markers, we analysed 127 black-faced impala individuals from the five subpopulations in Etosha NP, to determine the degree, if any, of hybridization within the park. We found that (a) the black-faced impala were highly genetically differentiated from the common impala (pairwise theta-values ranged from 0.18 to 0.39 between subspecies; overall value = 0.27) and (b) black-faced samples showed high levels of genetic variability [average expected heterozygosity (H(E)) = 0.61 +/- 0.01 SE], although not as high as that observed in the common impala (average H(E) = 0.69 +/- 0.02 SE). (c) No hybridization between the subspecies in Etosha was suggested. A Bayesian Markov Chain Monte Carlo approach revealed clear distinction of individuals into groups according to their subspecies of origin, with a zero level of 'genetic admixture' among subspecies.     

Transposition of autonomous and engineered impala transposons in Fusarium oxysporum and a related species

The impala transposon of Fusarium oxysporum is an active element. We demonstrated that the imp160 copy, transposed into the gene encoding nitrate reductase, is an autonomous element, since it excises from this gene and reinserts at a new genomic position in backgrounds free of active elements. An element in which the transposase gene was replaced by a hygromycin B resistance gene was used (1) to demonstrate the absence of endogenous transposase in several F. oxysporum strains and (2) to check the ability of different genomic copies of impala to transactivate this defective element. This two-component system allowed the identification of autonomous elements in two impala subfamilies and revealed that transactivation can occur between highly divergent elements. We also demonstrate that the autonomous copy transposes in a closely related species complex, F. moniliforme, in a fashion similar to that observed in F. oxysporium. The ability of impala to function as a two-component system and to transpose in a heterologous host promises further advances in our understanding of the factors that modulate transposition efficiency and demonstrates the potential of impala as a means of establishing a transposon tagging system for a wide range of fungal species.     

Antipredator behaviour of African ungulates around human settlements

As human populations grow and come into more frequent contact with wildlife, it is important to understand how anthropogenic disturbance alters wildlife behaviour. Using fine‐scale spatial analyses, we examined how proximity to human settlements affects antipredator responses of ungulates. We studied seven common ungulate species (Kirk's dik‐dik, Thomson's gazelle, impala, common warthog, common wildebeest, common zebra and Masai giraffe) in the Tarangire–Manyara ecosystem in northern Tanzania. In zebra and giraffe, flight responses to humans were significantly more likely when closer to settlements; however, there was a weak relationship between flight responses and distance to settlement in all other species. While there was largely a weak relationship between proximity to human settlements, the distribution of settlements in the landscape appears to affect wildlife behaviour, suggesting that animals perceive and respond to spatial variation in risk exerted by humans.     

Answering the call! Adapting a traditional hunting practice to monitor duiker populations

In several regions of the Congo Basin the call of an endangered duiker is traditionally used by hunters to attract animals. We explore the possibility to standardize this call method to improve day time transect counts. Our study shows that the call is particularly efficient for the most common duiker species [ Philantomba monticola (previously Cephalophus monticola ), Cephalophus callipygus and Cephalophus dorsalis ]. The call increases the number of direct sightings in secondary forests and counterbalances the bias caused by vegetation density in classic day time counts. The method is more effective during the first 4 min of the call and from 9.00 to 11.00 hours, particularly during the dry season. Hunting using the call does not significantly increase the sex bias (more males killed) obtained without the call. Compared with day time visual counts, the call method ensures a more reliable species identification because animals are better seen and for a longer time. Derived from a traditional practice, the call can be easily appropriated by local communities in participatory duiker surveys. However, the method is not recommended when multi-species surveys are to be carried out or when densities are to be estimated because the area surveyed per unit call is unknown.     

Impala,a transposon from Fusarium oxysporum,is active in the genome of Penicillium griseoroseum

An autonomous impala transposon trapped in Fusarium oxysporum by insertion within the niaD gene encoding nitrate reductase was introduced in the genome of the fungus Penicillium griseoroseum, a producer of pectinase enzymes. Through a phenotypic assay, we demonstrate that this element is able to excise from the niaD gene and to reinsert at new genomic positions. As in the original host, impala inserts into a TA site and footprints left by impala excisions are generally 5 bp. The fact that impala is able to transpose in P. griseoroseum offers the opportunity to develop a gene-tagging system based on this element with the objective to detect and clone genes related in pectinase production.