Habitat suitability for tsessebe Damaliscus lunatus lunatus

The distribution and numbers of tsessebe (Damaliscus lunatus lunatus) have declined considerably in South Africa, partly due to deteriorating habitat conditions. Identifying important habitat variables will assist in managing the species. The objective of this study was to identify habitat variables important for tsessebe and to develop a predictive model of habitat selection for this species in a savanna biome. The study was conducted in the Nylsvley Nature Reserve over a 2‐year period. A total of eighteen habitat variables were measured in ten plant communities at 200 sites. Logistic regression analyses were used to identify predictor variables and to construct a habitat model. Tsessebe were found <2 km from the nearest source of water, in flat areas with slopes of <3° and with <10% rockiness. Their distribution was not influenced by the woody component. Sites where tsessebe were present had significantly lower grass heights and tuft heights, with a higher grass density compared with areas not utilized by tsessebe. Nitrogen and sodium levels were also higher at present sites. Habitat type and grass height were the most significant predictors of tsessebe presence. The selected model had an overall percentage prediction of 85.0%. The model was subdivided into five vegetation‐specific models and each model was tested with independent data.     

Species' borders and dispersal barriers

Range limits of species are determined by combined effects of physical, historical, ecological, and evolutionary forces. We consider a subset of these factors by using spatial models of competition, hybridization, and local adaptation to examine the effects of partial dispersal barriers on the locations of borders between similar species. Prompted by results from population genetic models and biogeographic observations, we investigate the conditions under which species' borders are attracted to regions of reduced dispersal. For borders maintained by competition or hybridization, we find that dispersal barriers can attract borders whose positions would otherwise be either neutrally stable or moving across space. Borders affected strongly by local adaptation and gene flow, however, are repelled from dispersal barriers. These models illustrate how particular biotic and abiotic factors may combine to limit species' ranges, and they help to elucidate mechanisms by which range limits of many species may coincide.     

Demographic consequences for a threatened plant after the loss of its only disperser. Habitat suitability buffers limited seed dispersal

Seed dispersal links the end of a plant's reproductive cycle with the establishment of new recruits. Dispersal over short distances may lead to the local aggregation of individuals, slower population growth and, ultimately, to lower population densities. In this study, we analyse the demographic consequences for the shrub Daphne rodriguezii after the loss of its only seed disperser in an island ecosystem (Menorca Island, western Mediterranean). During a period of 8–10 years, we collected demographic data from five populations, four where the disperser is extinct (disrupted) and the only one in which it still persists (undisrupted). We calculated basic deterministic variables, analysed life table response experiments (LTRE) and their covariation among demographic traits, and simulated future population vulnerability. Population growth rate (λ) was either stable or negative and independent of whether the population was disrupted or not. Current and past population dynamics were similar in the two largest populations (one being the undisrupted), which suggests that the environmental conditions allow them to be stable regardless of seed disperser presence. Variation in λ was dependent on rainfall variability and was highly influenced by stasis and growth. There also existed tradeoffs between the former life traits and fecundity, which indicate strong competition when resources are limiting (e.g. high plant aggregation due to limited seed dispersal or low rainfall), and that could ultimately affect high‐elasticity demographic traits. Our study suggests that the population dynamic of D. rodriguezii is stable under the current conditions, and that where dispersal is limiting, important environmental changes (e.g. in habitat suitability and/or rainfall regime) might lead to local extinctions.     

Adiaspiromycosis in large free living carnivores

Adiaspiromycosis was identified in 6 animals in the examination of the lungs of 90 large carnivores. Emmonsia crescens (Chrysosporium parvum var. crescens) was demonstrated as the causative agent in 5 cases of disease — in the badger (Meles meles), the otter (Lutra lutra) and the fox (Vulpes vulpes). E. parva was demonstrated in the remaining case of disease in a fox. The badger is a new, up to the present unknown host of E. crescens. The sporadic occurrence of adiaspiromycosis in the fox and the otter classifies this disease among rare diseases of these animals.     

Habitat persistence,habitat availability and the evolution of dispersal

Many organisms live in ephemeral habitats, making dispersal a vital element of life history. Here, we investigate how dispersal rate evolves in response to habitat persistence, mean habitat availability and landscape pattern. We show that dispersal rate is generally lowered by reduced habitat availability and by longer habitat persistence. However, for habitats that persist for an average of ten times the length of a generation, we show a clear non-monotonic relationship between habitat availability and dispersal rate. Some patterns of available habitat result in populations with dispersal polymorphisms. We explain these observations as a metapopulation effect, with the rate of evolution a function of both within-population and between-population selection pressures. Individuals in corridors evolve much lower dispersal rates than those in the mainland populations, especially within long, narrow corridors. We consider the implications of the results for conservation.     

蜂桶寨自然保护区大熊猫生境适宜性评价与保护管理对策

对濒危野生动物而言,开展生境质量评价是完善就地保护措施、提高自然保护成效的基础。蜂桶寨自然保护区位于邛崃山系中段,是大熊猫模式标本的采集地。而此前有关该保护区大熊猫生境的研究主要集中在生境的选择上,生境适宜性评价方面的研究尚未开展。本文以海拔、坡度、植被类型、食物来源等4个生态因子为指标,通过构建景观连接度模型对保护区内大熊猫生境适宜性进行评价。结果表明,保护区内大熊猫不适宜生境面积、较适宜生境面积及最适宜生境面积分别为223.26、133.67和33.46 km2,分别占保护区总面积的57%、34%和9%。从空间分布来看,最适宜生境和较适宜生境在保护区内的分布较为破碎分散,大熊猫活动痕迹点更多地集中在生境适宜程度较高的区域。为加强该区大熊猫种群的科学保护,应控制敏感区域的人为活动,确保保护区内大熊猫个体在不同生境斑块之间迁移扩散。日常保护管理工作中应重点关注与黄水河自然保护区相连区域,并可适度扩大蜂桶寨自然保护区的管护范围。     

Risk and opportunity for humans coexisting with large carnivores

Models of Plio-Pleistocene hominid behavioral ecology often emphasize competition with large carnivores. This paper describes competition between modern humans and large carnivores in rural Uganda, including active, confrontational scavenging of carnivore kills by humans and carnivore attacks on humans. Information gathered from Ugandan Game Department archives (1923-1994) reveals that twentieth-century agropastoralists regularly tried to scavenge from leopard (Panthera pardus) and lion (Panthera leo) kills, and that these large carnivores have preyed on hundreds of humans in Uganda over the past several decades. Men were most often targets of carnivore attack, particularly while engaged in hunting-related activities. However attacks on men were less often lethal than attacks on women and children. Analyses show that lion attacks were more dangerous than leopard attacks. These data support recent contentions that hominids armed with even simple weapons can succeed in active, confrontational scavenging by chasing carnivores from kills. Hominids sharing East African habitats with large carnivores may have been regularly subject to attack.     

Habitat corridors function as both drift fences and movement conduits for dispersing flies

Corridors connect otherwise isolated habitat patches and can direct movement of animals among such patches. In eight experimental landscapes, we tested two hypotheses of how corridors might affect dispersal behavior. The Traditional Corridor hypothesis posits that animals preferentially leave patches via corridors, following them into adjacent patches. The Drift Fence hypothesis posits that animals dispersing through matrix habitat are diverted into patches with corridors because they follow corridors when encountered. House flies (Musca domestica L.), a species that prefers the habitat of our patches and corridors, were released in a central patch (100×100 m) and recaptured in peripheral patches that were or were not connected by a corridor. Flies were captured more frequently in connected than unconnected patches, thereby supporting the Traditional Corridor hypothesis. The Drift Fence hypothesis was also supported, as flies were captured more frequently in unconnected patches with blind (dead end) corridors than in unconnected patches of equal area without blind corridors. A second experiment tested whether these results might be dependent on the type of patch-matrix boundary encountered by dispersing flies and whether edge-following behavior might be the mechanism underlying the observed corridor effect in the first experiment. We recorded dispersal patterns of flies released along forest edges with dense undergrowth in the forest (“closed” edges) and along edges with little forest understory (“open” edges). Flies were less likely to cross and more likely to follow closed edges than open edges, indicating that when patch and corridor edges are pronounced, edge-following behavior of flies may direct them along corridors into connected patches. Because edges in the first experiment were open, these results also suggest that corridor effects for flies in that experiment would have been even stronger if the edges around the source patches and corridors had been more closed. Taken together, our results suggest that corridors can affect dispersal of organisms in unappreciated ways (i.e., as drift fences) and that edge type can alter dispersal behavior.     

Body mass in large extant and extinct carnivores

Body mass in six species of Plio-Pleistocene carnivores was estimated based on the relationship between mass and cross-sectional geometric properties, distal articular surface area, lengths and circumferences of proximal limb bones (femur and humerus) in 28 species of extant carnivores. All measures, except lengths, were found to give congruent body mass estimates. Two of the extinct carnivores ( Smilodon fatalis and Panthera atrox ) are estimated to be as much as one and a half times heavier than previously thought. Based on these results inferences are made concerning possible prey species.     

Detecting dispersal of Nuphar lutea in river corridors using microsatellite markers

1. River corridors are well-known for their role in plant dispersal. The buoyancy of seeds, the possibility of dispersal by vegetative fragments, and the frequency and efficiency of dispersal among different river catchments determine linear distribution patterns. Little is known about the relative importance of these factors to observed patterns of genetic variation.
2. One hundred and fifty-six Nuphar lutea individuals from forty-four sampling sites in the river catchments of the Cidlina River, the Mrlina River and the Labe River (Czech Republic) were studied using ten microsatellite markers. Interpretation of patterns in genetic variation allowed several conclusions about dispersal mechanisms.
3. Vegetative long-distance dispersal is probably very limited in this species. Only one multilocus genotype was found in more than one sampling site. The distance between the sites was about 75 km.
4. To explain the distribution of Bayesian based clusters of related multilocus genotypes, both along-river and inter-river long-distance dispersals have to be invoked.
5. A marginally significant tendency for higher genetic diversity in the lower part of the river Cidlina was detected. Continuous downstream dispersal of seeds by water currents could be a valid explanation.
6. Significant positive autocorrelation was found among individuals at within-river distances of up to 25 km. Repeated dispersal of seeds over distances in the range of tens of kilometers is common.     

Canine tooth strength and killing behaviour in large carnivores

Bending strength of upper canine teeth is examined among living canids, felids, hyaenids and several extinct species including sabretooth cats, borophagine dogs and the dire wolf, Canis dirus. The tooth is modelled as a cantilever with an elliptical cross-section. Using beam theory, the bending strength of the upper canine is calculated given a constant force applied to the canine tip. Results indicate that felids and hyaenids have relatively stronger canines than canids, particularly in bending about the anteroposterior (AP) rather than the mediolateral axis. It is suggested that canine shape reflects the forces produced during killing and feeding. As shown by an analysis of jaw muscle moment arms, felids and hyaenids have relatively stronger bites than canids. Moreover, the canines of hyaenids and felids are perhaps more likely to contact bone during feeding and killing and consequently may be subjected to larger and more frequent bending moments about the AP axis. The canines of sabretooth cats are shown to be more similar in shape and strength characteristics to those of living canids than felids, whereas those of the borophagine dogs and the dire wolf are closer to modern hyaenas.     

Secondary phorate poisoning of large carnivores in India

India, with its huge human population and fragmented wildlife habitat, is plagued with human–animal conflicts. In conflict areas, large carnivores are often primary targets for malicious poisoning. The effects of certain poisons do not stop with the target animal but also affects other species of wildlife in the form of secondary poisoning. This paper describes incidences of secondary poisoning of a tiger (Panthera tigris) and a black panther (melanistic Panthera pardus) in the Nilgiri Biosphere Reserve. Wild boars (Sus scrofa), which are considered pests in horticultural plantations, were the primary targets in both cases and were poisoned using phorate, a highly toxic organophosphorus compound. Tigers and leopards hold significant position in the upper most trophic level of the ecological pyramid and are grouped in schedule I of the Wildlife Protection Act of India. The tiger, as a species, is currently waging a grim battle of survival in the wild. The world over, leopard populations are also dwindling. The implications of the death of these endangered apex predators due to the increase in population of the ubiquitous wild boars are analysed. The merits of introducing a policy of selective culling of wild boars in conflict areas are discussed.     

Sabretoothed carnivores and the killing of large prey

Sabre-like canines clearly have the potential to inflict grievous wounds leading to massive blood loss and rapid death. Hypotheses concerning sabretooth killing modes include attack to soft parts such as the belly or throat, where biting deep is essential to generate strikes reaching major blood vessels. Sabretoothed carnivorans are widely interpreted as hunters of larger and more powerful prey than that of their present-day nonsabretoothed relatives. However, the precise functional advantage of the sabretooth bite, particularly in relation to prey size, is unknown. Here, we present a new point-to-point bite model and show that, for sabretooths, depth of the killing bite decreases dramatically with increasing prey size. The extended gape of sabretooths only results in considerable increase in bite depth when biting into prey with a radius of less than ～10 cm. For sabretooths, this size-reversed functional advantage suggests predation on species within a similar size range to those attacked by present-day carnivorans, rather than "megaherbivores" as previously believed. The development of the sabretooth condition appears to represent a shift in function and killing behaviour, rather than one in predator-prey relations. Furthermore, our results demonstrate how sabretoothed carnivorans are likely to have evolved along a functionally continuous trajectory: beginning as an extension of a jaw-powered killing bite, as adopted by present-day pantherine cats, followed by neck-powered biting and thereafter shifting to neck-powered shear-biting. We anticipate this new insight to be a starting point for detailed study of the evolution of pathways that encompass extreme specialisation, for example, understanding how neck-powered biting shifts into shear-biting and its significance for predator-prey interactions. We also expect that our model for point-to-point biting and bite depth estimations will yield new insights into the behaviours of a broad range of extinct predators including therocephalians (gorgonopsian + cynodont, sabretoothed mammal-like reptiles), sauropterygians (marine reptiles) and theropod dinosaurs.     

Habitat tracking, stasis and survival in Neogene large mammals

Species response to environmental change may vary from adaptation to the new conditions, to dispersal towards territories with better ecological settings (known as habitat tracking), and to extinction. A phylogenetically explicit analysis of habitat tracking in Caenozoic large mammals shows that species moving over longer distances during their existence survived longer. By partitioning the fossil record into equal time intervals, we showed that the longest distance was preferentially covered just before extinction. This supports the idea that habitat tracking is a key reaction to environmental change, and confirms that tracking causally prolongs species survival. Species covering longer distances also have morphologically less variable cheek teeth. Given the tight relationship between cheek teeth form and habitat selection in large mammals, this supports the well-known, yet little tested, idea that habitat tracking bolsters morphological stasis.     

Population structure,colonization processes and barriers for dispersal in Polish common hamsters (Cricetus cricetus)

The phylogeographic relationships of common hamster (Cricetus cricetus) populations in Poland were determined by the analysis of three partial mtDNA sequences: control region, cytochrome b and 16S rRNA. A phylogenetic tree as well as parsimony network, consistently separate Polish common hamsters into two groups: E1 being so far specific for the area of Poland, and P3 which clusters inside a Pannonian lineage, previously described from the Carpathian Basin. Polish hamsters do not share any haplotypes with the ‘North’– lineage from Germany and Western Europe, although Poland most likely represents the main migration corridor from the eastern distribution centre to the western boundary of the species range. Fossil and DNA data indicate a very recent appearance of the E1 lineage in the Polish Uplands, probably at the very end of the last glaciation. On the other hand, the Pannonian group entered southern Poland as early as the second stadial of the last glaciation (Middle Vistulian 53.35 ka). The hamster lineages in Poland seem to show different population structures and demographic histories.