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.     

Seed dispersal by carnivores in temperate and tropical dry forests

The seed dispersal mechanisms and regeneration of various forest ecosystems can benefit from the actions of carnivores via endozoochory. This study was aimed to evaluate the role of carnivores in endozoochory and diploendozoochory, as well as their effect on seed viability, scarification, and germination in two forest ecosystems: temperate and tropical dry forest. We collected carnivore scat in the Protected Natural Area of Sierra Fría in Aguascalientes, Mexico, for 2 years to determine the abundance and richness of seeds dispersed by each carnivore species, through scat analysis. We assessed seed viability through optical densitometry using X‐rays, analyzed seed scarification by measuring seed coat thickness using a scanning electron microscope, and evaluated seed germination in an experiment as the percentage of seeds germinated per carnivore disperser, plant species, and forest type. In the temperate forest, four plant species (but mainly Arctostaphylos pungens) were dispersed by four mammal species. The gray fox dispersed the highest average number of seeds per scat (66.8 seeds). Bobcat dispersed seeds through diploendozoochory, which was inferred from rabbit (Sylvilagus floridanus) hair detected in their scats. The tropical dry forest presented higher abundance of seeds and richness of dispersed plant species (four species) than in the temperate forest, and the coati dispersed the highest number of seeds (8,639 seeds). Endozoochory and diploendozoochory did not affect viability in thick‐testa seeds (1,480 µm) in temperate forest and thin‐testa seeds (281 µm) in tropical dry forest. Endozoochory improved the selective germination of seeds. Nine plant species were dispersed by endozoochory, but only one species (Juniperus sp.) by diploendozoochory. These results suggest that carnivores can perform an important ecological function by dispersing a great abundance of seeds, scarifying these seeds causing the formation of holes and cracks in the testas without affecting viability, and promoting the selective germination of seeds.     

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.     

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.     

中国东北虎栖息地分析与潜在生态廊道构建

东北虎（Panthera tigris altaica）是现存5个虎亚种中体型最大者,其作为全球生物多样性保护的旗舰物种,在维持健康生态系统功能中占据不可替代的重要地位。近几十年来,由于东北虎栖息地受到人类活动强烈干扰,致使栖息地破碎化,主要栖息地孤立分布,呈现岛状,天然生态廊道消失殆尽,东北虎的保护面临巨大挑战。因此,确定东北虎关键栖息地,构建与恢复东北虎栖息地之间的生态廊道十分必要。本研究运用专家模型结合东北虎栖息地选择规律和栖息地特征,综合分析植被类型、国家级与省级自然保护区分布、地形因子以及人为干扰因子共7个主要影响因子;通过层次分析法(AHP)获得各影响因子的相对权重值,运用加权线性方程获得了东北虎潜在适宜栖息地,并确定了东北虎核心分布区以及分布区间的综合代价值。通过廊道设计模型（Linkage mapper）得到东北虎核心栖息地间的潜在生态廊道。结果得到了21条东北虎潜在生态廊道,对打通国内零星分布区,特别是张广才岭-完达山-老爷岭之间的迁移通道、扩大东北虎生存空间具有现实指导意义。     

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.     

Detection of barriers to dispersal is masked by long lifespans and large population sizes

Population genetic analyses of species inhabiting fragmented landscapes are essential tools for conservation. Occasionally, analyses of fragmented populations find no evidence of isolation, even though a barrier to dispersal is apparent. In some cases, not enough time may have passed to observe divergence due to genetic drift, a problem particularly relevant for long‐lived species with overlapping generations. Failing to consider this quality during population structure analyses could result in incorrect conclusions about the impact of fragmentation on the species. We designed a model to explore how lifespan and population size influence perceived population structure of isolated populations over time. This iterative model tracked how simulated populations of variable lifespan and population size were affected by drift alone, using a freshwater mussel, Quadrula quadrula (mapleleaf), as a model system. In addition to exhibiting dramatic lifespan variability among species, mussels are also highly imperiled and exhibit fragmentation by dams throughout the range of many species. Results indicated that, unless population size was small (<50 individuals) or lifespan short (<22 years), observing genetic divergence among populations was unlikely. Even if wild populations are isolated, observing population structure in long‐lived mussels from modern damming practices is unlikely because it takes longer for population structure to develop in these species than most North American dams have existed. Larger population sizes and longer lifespans increase the time needed for significant divergence to occur. This study helps illuminate the factors that influence genetic responses by populations to isolation and provides a useful model for conservation‐oriented research.     

Habitat suitability and demography,a time‐dependent relationship

The habitat suitability index, which reflects spatial variability in species occurrence probability, has been shown to exhibit various contrasting relationships with local demographic performances (survival, productivity) in several species. One proposed explanation for these discrepancies is that the link between the habitat suitability index and demography is influenced by density‐dependent, temporally variable processes. Based on the survival rates of more than 3,000 nests monitored over 12 years in the North African Houbara Bustard, we investigated whether the habitat suitability index computed over the species breeding range is related to nest survival throughout the breeding season, accounting for variation in meteorological conditions. We found that the relationship between the habitat suitability index and nest survival progressively changes along the breeding season and that this intra‐annual variation is consistent between years. Our results support the hypothesis that variation in space use occurs intra‐annually and that biotic interactions throughout the breeding season strongly influence the habitat suitability index–demography relationship.     

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.     

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。     

Climate change and plant dispersal along corridors in fragmented landscapes of Mesoamerica

Climate change is a threat to biodiversity, and adaptation measures should be considered in biodiversity conservation planning. Protected areas (PA) are expected to be impacted by climate change and improving their connectivity with biological corridors (BC) has been proposed as a potential adaptation measure, although assessing its effectiveness remains a challenge. In Mesoamerica, efforts to preserve the biodiversity have led to the creation of a regional network of PA and, more recently, BC. This study evaluates the role of BC for facilitating plant dispersal between PA under climate change in Mesoamerica. A spatially explicit dynamic model (cellular automaton) was developed to simulate species dispersal under different climate and conservation policy scenarios. Plant functional types (PFT) were defined based on a range of dispersal rates and vegetation types to represent the diversity of species in the region. The impacts of climate change on PA and the role of BC for dispersal were assessed spatially. Results show that most impacted PA are those with low altitudinal range in hot, dry, or high latitude areas. PA with low altitudinal range in high cool areas benefit the most from corridors. The most important corridors cover larger areas and have high altitude gradients. Only the fastest PFT can keep up with the expected change in climate and benefit from corridors for dispersal. We conclude that the spatial assessment of the vulnerability of PA and the role of corridors in facilitating dispersal can help conservation planning under a changing climate.     

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.     

浙江清凉峰国家级自然保护区华南梅花鹿栖息地适宜性评价

理解环境因子对物种空间分布的影响,评价栖息地适宜性现状并预测潜在分布区,对野生动物的管理和保护具有重要意义。华南梅花鹿（Cervus pseudaxis）属国家I级重点保护野生动物,现仅分布于安徽、浙江、江西等狭小片区内。浙江清凉峰自然保护区千顷塘区域是华南梅花鹿的重要分布区,但其面积较小,严重限制了华南梅花鹿的种群发展,亟需对千顷塘及周边区域的栖息地质量进行评价,为华南梅花鹿的保护和野外放归提供科学依据。本研究利用红外相机监测千顷塘区域华南梅花鹿的分布,结合遥感等技术手段获得地形、植被、水源以及人为干扰等8种环境因子,利用MaxEnt构建华南梅花鹿栖息地适宜性模型,对以千顷塘为中心50 km×50 km的范围进行栖息地适宜性评价。研究结果表明,华南梅花鹿倾向于选择海拔1050-1240 m范围内,距道路100-900 m和距人口聚居区3200-3800 m的相对平缓地带。千顷塘区域华南梅花鹿栖息地保护较好,适宜栖息地面积为2224 hm2,占该区域39.1%。千顷塘周边适宜性较高的区域主要为位于其西南部约10 km的山区,该区域为华南梅花鹿提供了3253 hm2的潜在适宜栖息地。建议降低保护区千顷塘区域内的人为干扰,并在其西南部山区尝试开展圈养种群的野外放归工作,以促进其种群发展。     

Habitat suitability modelling and implications for management of roan antelopes in Kenya

The roan antelope is locally endangered in Kenya with <50 individuals remaining in Ruma National Park (RNP). An understanding of the habitat requirements is essential to formulate habitat management strategies for species recovery. This study identifies habitat and management features affecting roan distribution in different seasons using information‐theoretic and multimodel inference (MMI) techniques. MMI averaged models were coupled with GIS data to develop habitat suitability maps. Results showed that roan habitat suitability is determined by different factors in different seasons but overall habitat was more important than management. Best predictors of roan incidence were wooded grassland, open grassland and water points. Water was more significant in the dry season whilst vegetation burned status, slope, soil type, distances to snares, park fence and security gates were important predictors at other seasons. Receiver operating characteristic (ROC) plots confirmed that the models fitted well to the data (AUC>0.9). Sustainable conservation of roans in RNP can be achieved via long‐term habitat management including prescribed burning and construction of more water points and short‐term urgent solutions to key management issues, especially control of poaching.