High Levels Of Human Disturbance Research Articles

Population changes in Gharial (Gavialis gangeticus) vary spatially in Chitwan National Park, Nepal

Gharials, large crocodilians found only in South Asia, are widely seen as a flagship species for river conservationin Nepal, especially in Chitwan National Park, where a headstart program has supplemented the populationsince 1981. The population has shown signs of recovery only in the last decade, so continued monitoring of populationtrends is vital for conservation. We conducted annual winter population surveys for gharial in Chitwan between 2017and 2022, during which we also characterized riverbank substrate availability and basking preferences. We documentedpotential threats to the species in Chitwan throughout the year. Overall, we counted an increasing number of Gharialsin Chitwan; however mixed-effects modelling of Gharial encounter rate showed that increasing encounters rates are notevenly distributed throughout available habitat, with some river stretches having stable or decreasing trends. Encounterrates on the Rapti River increased in all transects, compared to more variable results on the Narayani River, likelyattributable to higher levels of human disturbance and the impact of captivity on habitat selection. Fewer Gharials wereseen in transects with high levels of disturbance due to sand mining and the extraction of river substrates, highlightingthis threat as a major concern. Regular reports of bycatch in illegal gillnets was the major observed source of mortality.A lack of an increasing population trend in the stretch above a large barrage suggests that recruitment is minimal inthis area, and the dam likely has a negative impact on upstream Gharial recruitment. We cautiously suggest that theChitwan population is recovering, but that recovery is hampered by threats, especially substrate extraction, illegal gillnetfishing, and river fragmentation by a dam.

Ecological and biological indicators of the accuracy of species distribution models: lessons from European bryophytes

The predictive power of species distribution models (SDMs) varies substantially among species depending on their ecological and life‐history traits, but which of these traits are the most relevant and how they influence species ‘predictability' remains an area of debate. Here, we address these questions in bryophytes. SDMs employing macroclimatic, topographic and edaphic predictors were calibrated for 411 species in Europe and externally evaluated using an independent dataset. Regression models were implemented to determine whether species characteristics, including life‐history traits, ecological preference and niche breadth, determine the accuracy of SDMs. Variation in SDM accuracy among species was significantly explained by species characteristics, supporting the hypothesis that the strength of species–environment correlations is affected by characteristics of the species themselves. The percent variance of SDM accuracy explained by species traits, however, substantially varied between 9 and 57% depending on the evaluation metrics used. The lower correlation observed between species traits and MaxKappa and the Boyce index than with area under the curve (AUC) and MaxTSS suggests that the former are less suitable than the latter for determining species ‘predictability' based on their traits. SDM accuracy decreased from species restricted to pristine habitats to species thriving in eutrophic habitats with high levels of human disturbance. The widespread distribution of man‐made habitats in fact opens the door for the spread of now ubiquitous species, even in environments that would primarily not be suitable for them. Such species, likely to occur anywhere, reach very high to full occupancy rates, thereby decreasing the accuracy of models aiming at predicting their distributions. The fact that AUC and MaxTSS were higher for species from pristine habitats is important in a conservation context, as ubiquitous species from eutrophic, disturbed environments are precisely the ones of lower conservation relevance.

Using camera trap bycatch data to assess habitat use and the influence of human activity on African elephants (Loxodonta africana) in Kasungu National Park, Malawi

African elephants (Loxodonta africana) are increasingly exposed to high levels of human disturbance and are threatened by poaching and human–elephant conflict. As anthropogenic pressures continue to increase, both inside and outside protected areas, understanding elephant behavioural responses to human activity is required for future conservation management. Here, we use bycatch data from camera trap surveys to provide inferences on elephant habitat use and temporal activity in Kasungu National Park (KNP), Malawi. The KNP elephant population has declined by ~ 95% since the late 1970s, primarily because of intensive poaching, and information on elephant ecology and behaviour can assist in the species’ recovery. Using occupancy modelling, we show that proximity to water is the primary driver of elephant habitat use in KNP, with sites closer to water having a positive effect on elephant site use. Our occupancy results suggest that elephants do not avoid sites of higher human activity, while results from temporal activity models show that elephants avoid peak times of human activity and exhibit primarily nocturnal behaviour when using the KNP road network. As key park infrastructure is located near permanent water sources, elephant spatiotemporal behaviour may represent a trade-off between resource utilisation and anthropogenic-risk factors, with temporal partitioning used to reduce encounter rates. Increased law enforcement activity around permanent water sources could help to protect the KNP elephant population during the dry season. Our findings highlight that camera trap bycatch data can be a useful tool for the conservation management of threatened species beyond the initial scope of research.

Passive Acoustic Monitoring as a Tool to Investigate the Spatial Distribution of Invasive Alien Species

Invasive alien species (IAS) are a threat to biodiversity and ecosystem function worldwide. Unfortunately, researchers, agencies, and other management groups face the unresolved challenge of effectively detecting and monitoring IAS at large spatial and temporal scales. To improve the detection of soniferous IAS, we introduced a pipeline for large-scale passive acoustic monitoring (PAM). Our main goal was to illustrate how PAM can be used to rapidly provide baseline information on soniferous IAS. To that aim, we collected acoustic data across Puerto Rico from March to June 2021 and used single-species occupancy models to investigate species distribution of species in the archipelago and to assess the peak of vocal activity. Overall, we detected 16 IAS (10 birds, 3 mammals, and 3 frogs) and 79 native species in an extensive data set with 1,773,287 1-min recordings. Avian activity peaked early in the morning (between 5 a.m. and 7 a.m.), while amphibians peaked between 1 a.m. and 5 a.m. Occupancy probability for IAS in Puerto Rico ranged from 0.002 to 0.67. In general, elevation and forest cover older than 54 years were negatively associated with IAS occupancy, corroborating our expectation that IAS occurrence is related to high levels of human disturbance and present higher occupancy probabilities in places characterized by more intense human activities. The work presented here demonstrates that PAM is a workable solution for monitoring vocally active IAS over a large area and provides a reproducible workflow that can be extended to allow for continued monitoring over longer timeframes.

Association of human disturbance and gastrointestinal parasite infection of yellow baboons in western Tanzania.

Human disturbance is an ongoing threat to many wildlife species, manifesting as habitat destruction, resource overuse, or increased disease exposure, among others. With increasing human: non-human primate (NHP) encounters, NHPs are increasingly susceptible to human-introduced diseases, including those with parasitic origins. As such, epidemiology of parasitic disease is becoming an important consideration for NHP conservation strategies. To investigate the relationship between parasite infections and human disturbance we studied yellow baboons (Papio cynocephalus) living outside of national park boundaries in western Tanzania, collecting 135 fresh faecal samples from nine troops occupying areas with varying levels of human disturbance. We fixed all samples in 10% formalin and later evaluated parasite prevalence and abundance (of isotrichid ciliates and Strongylida). We identified seven protozoan and four helminth taxa. Taxa showed varied relationships with human disturbance, baboon troop size and host age. In four taxa, we found a positive association between prevalence and troop size. We also report a trend towards higher parasite prevalence of two taxa in less disturbed areas. To the contrary, high levels of human disturbance predicted increased abundance of isotrichid ciliates, although no relationship was found between disturbance and Strongylida abundance. Our results provide mixed evidence that human disturbance is associated with NHP parasite infections, highlighting the need to consider monitoring parasite infections when developing NHP conservation strategies.

The bear-berry connection: Ecological and management implications of brown bears' food habits in a highly touristic protected area

Diet studies are essential to understand animal ecology and ecosystem dynamics, especially in the case of large omnivores. These studies are particularly relevant in areas where human disturbance is intense and, thus, species dietary patterns might change due to the easy accessibility of food resources of human origin, which may hinder the ecosystem services these species provide. We assessed the diet of brown bears (Ursus arctos) by DNA metabarcoding in Tatra National Park (southern Poland), a highly touristic protected area. Brown bears' diet showed a marked seasonality, a characteristic feature of brown bear populations relying on natural foods. Graminoids represented the main food during spring, while fleshy-fruited plants became more important from mid-summer. Fleshy-fruited plants were present in 56% of faeces and during the entire activity period of bears, revealing that fruits play a pivotal role in the feeding ecology of Tatra brown bears. Two berry species, Vaccinium myrtillus and Rubus idaeus, were the most frequently detected (in 42% and 20% of faeces, respectively). The large consumption of fleshy-fruited plants, and particularly of berries, suggests that, despite high levels of human disturbance in the area, brown bears still play a key role as seed dispersers. Management strategies focused on an effective waste management, control of berry picking, strict regulations about human activities in specific areas during sensitive periods in the feeding ecology of bears, and the lack of artificial food provisioning are crucial to ensure the seed dispersal processes and associated ecosystem services that bears and other frugivores provide.

Moths (Insecta: Lepidoptera) of Delhi, India: An illustrated checklist based on museum specimens and surveys.

BackgroundThere have been several recent checklists, books and publications about Indian moths; however, much of this work has focused on biodiversity hotspots such as North-east India, Western Ghats and Western Himalayas. There is a lack of published literature on urban centres in India, despite the increased need to monitor insects at sites with high levels of human disturbance. In this study, we examine the moths of Delhi, the national capital region of India, one of the fastest growing mega-metropolitan cities. We present a comprehensive checklist of 338 moths species using 8 years of light trapping data (2012-2020) and examining about 2000 specimens from historical collections at the National Pusa Collection of ICAR-Indian Agricultural Research Institute, New Delhi (NPC-IARI) spanning over 100 years (1907-2020). The checklist comprises moths from 32 families spanning 14 superfamilies with Noctuoidea (48.5%) and Pyraloidea (20.4%) being the the two most dominant superfamilies. We provide links to images of live individuals and pinned specimens for all moths and provide detailed distribution records and an updated taxonomic treatment.New informationThis is the first comprehensive annotated checklist of the moths of Delhi. The present study adds 234 species to the biodiversity of moths from Delhi that were not reported previously, along with illustrations for 195 species.

Effects of human disturbance on postnatal growth and baseline corticosterone in a long-lived bird.

Prolonged or repeated episodes of environmental stress could be especially detrimental for developing young, via impaired growth or development. Despite this, most studies investigating the effects of human recreational and tourism activities have focused on adults. An increasing demand for nature-based tourism in remote locations means that many seabirds, which have evolved largely in the absence of predators and humans, are being exposed to novel pressures. The slow-growing semi-precocial nestlings of the European storm petrel Hydrobates pelagicus experience higher mortality rates in nests exposed to human recreational disturbance. Here, we examine whether surviving nestlings reared in disturbed areas are also affected via changes in growth trajectories and baseline circulating glucocorticoids. Nestlings reared in high-disturbance areas displayed delayed mass growth, and we found weak evidence for slower rates of mass gain and tarsus growth, compared with nestlings reared in undisturbed areas. There were no differences in wing growth, consistent with prioritization of long wings, important for post-fledging survival. A tendency for a less marked age-related decline in corticosterone (CORT) in disturbed nestlings offers limited evidence that changes in growth trajectories were mediated by baseline CORT. However, disturbed nestlings could have experienced overall higher GC exposure if the acute GC response was elevated. 'Catch-up' growth enabled high-disturbance nestlings to overcome early constraints and achieve a similar, or even larger, asymptotic body size and mass as low-disturbance nestlings. While catch-up growth has been shown to carry costs for parents and offspring, the effects of disturbance were slight and considerably smaller than growth alterations driven by variation in environmental conditions between years. Nonetheless, effects of human recreational activities could be exacerbated under higher levels of human disturbance or in the presence of multiple pressures, as imposed by present rapid rates of environmental change.

Importance of isolated forest fragments and low intensity agriculture for the long-term conservation of the green peafowl Pavo muticus

AbstractLow intensity subsistence agriculture is generally believed to be less damaging to wildlife than intensive farming. As Myanmar is undergoing rapid modernization, subsistence farming may shift to intensive agriculture, resulting in increased threats to species of conservation concern such as the green peafowl Pavo muticus. Here we investigate habitat use of the green peafowl in a low intensity agricultural landscape surrounding a small forest fragment in southern Shan State, Myanmar. The forest belongs to Nan Kone Buddha Monastery and the green peafowl is protected from hunting in the area on the basis of religious beliefs. We established three survey transects with a total length of 3,414 m. During February 2016–January 2017 we conducted surveys twice daily for 4 consecutive days every month, walking all transects in both directions in the mornings and afternoons and recording visual and auditory peafowl encounters. We estimated peafowl density to be 2.63 animals/km2 in the less disturbed western part of the study area and 1.13 animals/km2 in the eastern part, which had higher levels of human disturbance. The peafowl's habitat use was significantly non-random, with forest patches being the most utilized habitat, followed by croplands. Within a 300 m buffer zone around the forest patch, the order of habitat preference was crop > scrub > fallow, with crop significantly preferred over the other two habitats. We conclude that preserved isolated forest blocks adjacent to community-managed agricultural areas are important for green peafowl conservation, and discuss the implications for long-term conservation management of the species.

Remnants of native forests support carnivore diversity in the vineyard landscapes of central Chile

AbstractCarnivores play an important role in ecosystem functioning as apex predators. However, most carnivore species are threatened or have been extirpated in human-dominated landscapes. The Mediterranean region of central Chile is a biodiversity hotspot, but expansion of agricultural areas such as vineyards is degrading wildlife habitat. We estimated the species richness and composition of carnivore communities in remnant fragments of sclerophyllous forest-shrubland in the vineyard landscapes of central Chile to evaluate the effects of human disturbance at different spatial scales. We tested two hypotheses: (1) vineyard landscapes with higher levels of human disturbance support a lower diversity of native carnivores in fragments of remnant native vegetation compared to landscapes with larger areas of natural habitat, and (2) habitat specialists and generalists respond differentially to human influence at the habitat vs landscape spatial scale. We used camera traps at 12 sites across the study area and evaluated the impact of human disturbance indicators on the richness and detection frequency of carnivore species. We found that human population density negatively affected carnivore richness and was associated with a lower detection frequency of the Vulnerable guiñaLeopardus guigna. The presence of domestic dogs also had a negative effect on the detection frequency of the guiña and the two native species of foxes, the culpeoLycalopex culpaeusand South American grey foxLycalopex griseus. We conclude that protecting remnants of native forest in vineyard landscapes is crucial for carnivore conservation in central Chile.

The importance of natural versus human factors for ecological conditions of streams and rivers

Streams are influenced by watershed-scale factors, such as climate, geology, topography, hydrology, and soils, which mostly vary naturally among sites, as well as human factors, agriculture and urban development. Thus, natural factors could complicate assessment of human disturbance. In the present study, we use structural equation modeling and data from the 2008–2009 United States National Rivers and Streams Assessment to quantify the relative importance of watershed-scale natural and human factors for in-stream conditions. We hypothesized that biological condition, represented using a diatom multimetric index (MMI), is directly affected by in-stream physicochemical environment, which in turn is regulated by natural and human factors. We evaluated this hypothesis at both national and ecoregion scales to understand how influences vary among regions. We found that direct influences of in-stream environment on diatom MMIs were greater than natural and human factors at the national scale and in all but one ecoregion. Meanwhile, in-stream environments were jointly explained by natural variations in precipitation, base flow index, hydrological stability, % volcanic rock, soil water table depth, and soil depth and by human factors measured as % crops, % other agriculture, and % urban land use. The explained variance of in-stream environment by natural and human factors ranged from 0.30 to 0.75, for which natural factors independently accounted for the largest proportion of explained variance at the national scale and in seven ecoregions. Covariation between natural and human factors accounted for a higher proportion of explained variance of in-stream environment than unique effects of human factors in most ecoregions. Ecoregions with relatively weak effects by human factors had relatively high levels of covariance, high levels of human disturbance, or small ranges in human disturbance. We conclude that accounting for effects of natural factors and their covariation with human factors will be important for accurate ecological assessments.

Offshore refuges support higher densities and show slower population declines of wintering Ruddy Turnstones Arenaria interpres

ABSTRACTCapsule: Wintering Ruddy Turnstones Arenaria interpres occur in higher densities and their populations decline less on, or close to, offshore refuges than on mainland sites subject to greater levels of human disturbance.Aim: To compare wintering densities of Ruddy Turnstones and changes in counts across time from sites with differing levels of human disturbance.Methods: Long-term counts of Ruddy Turnstones (1998/1999 to 2015/2016) were used from 19 sites (two offshore refuges and 17 mainland sites subject to higher levels of human disturbance) in northeast England. No direct measure of human disturbance was available for our mainland sites; instead we used questionnaires (n = 690) to understand how far people travelled to visit the coast and then used this distance with human population densities in a buffer around each site as a proxy for human disturbance levels.Results: After controlling for the extent of their preferred habitat at each site (rocky shore) we found: (i) the closer each of the 19 sites was to the nearest offshore refuge the higher the density of Ruddy Turnstones and (ii) bird counts were stable at the two refuge sites, whereas, on average, counts declined at the 17 mainland sites. However, no relationship was found between Ruddy Turnstone counts from 17 mainland sites and human population densities within differing distances from each site (up to 10 km).Conclusions: Our work suggests that Ruddy Turnstones made greater use of relatively undisturbed areas (offshore refuges) than those subject to greater disturbance by humans (mainland sites). Although the use of refuges and mainland in our study area was not well known, observations from 11 radio-tagged Ruddy Turnstones suggest that individual birds did use both locations. In a broader context, our work concurs with other studies that highlight the need for refuges with limited or no human access.

Multispecies hierarchical modeling reveals variable responses of African carnivores to management alternatives.

Carnivore communities face unprecedented threats from humans. Yet, management regimes have variable effects on carnivores, where species may persist or decline in response to direct or indirect changes to the ecosystem. Using a hierarchical multispecies modeling approach, we examined the effects of alternative management regimes (i.e., active vs. passive enforcement of regulations) on carnivore abundances and group sizes at both species and community levels in the Masai Mara National Reserve, Kenya. Alternative management regimes have created a dichotomy in ecosystem conditions within the Reserve, where active enforcement of regulations maintains low levels of human disturbance in the Mara Triangle and passive enforcement of regulations in the Talek region permits multiple forms of human disturbance. Our results demonstrate that these alternative management regimes have variable effects on 11 observed carnivore species. As predicted, some species, such as African lions and bat-eared foxes, have higher population densities in the Mara Triangle, where regulations are actively enforced. Yet, other species, including black-backed jackals and spotted hyenas, have higher population densities in the Talek region where enforcement is passive. Multiple underlying mechanisms, including behavioral plasticity and competitive release, are likely causing higher black-backed jackals and spotted hyena densities in the disturbed Talek region. Our multispecies modeling framework reveals that carnivores do not react to management regimes uniformly, shaping carnivore communities by differentially producing winning and losing species. Some carnivore species require active enforcement of regulations for effective conservation, while others more readily adapt (and in some instances thrive in response) to lax management enforcement and resulting anthropogenic disturbance. Yet, high levels of human disturbance appear to be negatively affecting the majority of carnivores, with potential consequences that may permeate throughout the rest of the ecosystem. Community approaches to monitoring carnivores should be adopted as single species monitoring may overlook important intra-community variability.

Abundance estimate of the Amazon River dolphin (Inia geoffrensis) and the tucuxi (Sotalia fluviatilis) in southern Ucayali, Peru

We present results of the first simultaneous visual and acoustic surveys for Amazon River dolphins ( Inia geoffrensis ) and tucuxi ( Sotalia fluviatilis ), undertaken in Yarinacocha Lagoon, Ucayali, Peru (length = 20 km, area = 12 km -2 ). A total of 324 Sotalia observations and 44 Inia observations were recorded in boat-based transects. Based upon total survey effort, we estimated Sotalia had a mean density ± SE of 1.98 ± 4.6 ind km -2 and an overall abundance of 34 individuals (95% CI: 28 to 40). Average density for Inia was 0.2 ± 1.2 ind km -2 with overall abundance estimated at 3 individuals (95% CI: 0 to 8). Visual surveys observed more Sotalia individuals during earlier hours of the day and during the dry season. Preliminary acoustic surveys undertaken with C-POD passive acoustic monitoring devices indicated a diel pattern in detections of cetacean vocalization with more diurnal activity and with detections ceasing from midnight until 10:00 AM. This work highlights the possibility of monitoring both river dolphin species through visual and acoustic surveys to generate baseline information on abundance trends and distribution patterns in the Ucayali region, an area with high levels of human disturbance.

The effects of urbanization and human disturbance on problem solving in juvenile house finches (Haemorhous mexicanus)

Urbanization exposes wildlife to unfamiliar environments, including novel structures and food sources. Adapting to such anthropogenic conditions may require superior innovation and problem-solving skills (e.g., for navigating, foraging). Human presence in urban areas is a particular biotic challenge that may impact problem-solving capabilities in wildlife. Urban animals may be superior problem solvers in the face of human disturbance, due to familiarity with—and reduced fear of—humans. Alternately, rural animals may be better innovators if heightened fear responses from unfamiliar humans facilitate problem solving. Here, we studied the relationship between human disturbance, urbanization, and the ability to solve a novel foraging problem in wild-caught juvenile house finches (Haemorhous mexicanus). This songbird is a successful urban dweller and native of the American desert southwest. In captivity, juvenile finches from urban and rural populations were presented with a novel foraging task (sliding a lid covering their typical food dish) and then exposed to regular periods of high or low human disturbance over several weeks before again being presented with the task. We found that rural, high-disturbance birds showed reduced task performance compared to highly disturbed urban finches. This is consistent with the hypothesis that urban birds are less affected by human disturbance due to habituation or adaptation. Additionally, we found that the best behavioral predictor of solving success was related to visual inspection of the problem and that urban low-disturbance birds exhibited this behavior more than rural high-disturbance birds. Overall, these findings suggest that urbanization and habituation to humans predict avian response to novel problems. As Earth’s landscapes become more urbanized, wildlife is exposed to many new anthropogenic challenges. In particular, animals in cities may have to locate food in unique ways and/or cope with increased human presence. We tested the effects of urbanization and human disturbance on problem solving in juveniles of a common urban and rural songbird (the house finch, H. mexicanus). We found that, when subjected to high levels of human disturbance, urban birds outperformed rural conspecifics on a novel foraging task (sliding open a lid to uncover food). We also found that task focus (i.e., average bout length of inspecting the dish) was an important predictor of problem solving. Our results suggest that acclimation to humans may be important for the superior behavioral performance of urban house finches and ultimately their colonization of many North American cities.

Factors affecting the breeding success of the African Black Oystercatcher (Haematopus moquini): a perspective on protection and food availability

Breeding success (fledglings pair−1 y−1) of the Red-listed African Black Oystercatcher (Haematopus moquini) is highly variable, both spatially and temporally. Despite a diversity of natural factors causing this variability, there is evidence that two anthropogenic factors, i.e. disturbance and an introduced mussel (Mytilus galloprovincialis), are having an impact on the local breeding success of this species. Using a data set comprising 87 site-years of nest-monitoring data across most of the species’ breeding range, we analysed the extent and causes of variability in breeding success. Breeding success differed across three population categories defined by varying levels of human disturbance: island populations, protected mainland populations, and unprotected mainland populations. Differences in breeding success between island populations and protected mainland populations were likely due to differing exposure to predators; however, differences between protected and unprotected mainland populations were unlikely caused by this as both experience equivalent predation levels (although from different predators). Protection only improved the breeding success of oystercatchers in very high-quality habitats (with a high biomass of alien mussels), and where populations were ‘released’ from high levels of human disturbance. In unprotected mainland areas, human activity impacted on the breeding success of local populations primarily through predation of small chicks by uncontrolled dogs, and by rising tides drowning chicks that were hiding from human disturbance. The findings of this study note the potential conservation dilemma resulting from an invasive species improving the conservation status of a Red-listed species, and encourage the implementation of restricted sites in high-quality habitats with high breeding pair densities.

Genetic and phenotypic variation along an ecological gradient in lake trout Salvelinus namaycush.

BackgroundAdaptive radiation involving a colonizing phenotype that rapidly evolves into at least one other ecological variant, or ecotype, has been observed in a variety of freshwater fishes in post-glacial environments. However, few studies consider how phenotypic traits vary with regard to neutral genetic partitioning along ecological gradients. Here, we present the first detailed investigation of lake trout Salvelinus namaycush that considers variation as a cline rather than discriminatory among ecotypes. Genetic and phenotypic traits organized along common ecological gradients of water depth and geographic distance provide important insights into diversification processes in a lake with high levels of human disturbance from over-fishing.ResultsFour putative lake trout ecotypes could not be distinguished using population genetic methods, despite morphological differences. Neutral genetic partitioning in lake trout was stronger along a gradient of water depth, than by locality or ecotype. Contemporary genetic migration patterns were consistent with isolation-by-depth. Historical gene flow patterns indicated colonization from shallow to deep water. Comparison of phenotypic (Pst) and neutral genetic variation (Fst) revealed that morphological traits related to swimming performance (e.g., buoyancy, pelvic fin length) departed more strongly from neutral expectations along a depth gradient than craniofacial feeding traits. Elevated phenotypic variance with increasing water depth in pelvic fin length indicated possible ongoing character release and diversification. Finally, differences in early growth rate and asymptotic fish length across depth strata may be associated with limiting factors attributable to cold deep-water environments.ConclusionWe provide evidence of reductions in gene flow and divergent natural selection associated with water depth in Lake Superior. Such information is relevant for documenting intraspecific biodiversity in the largest freshwater lake in the world for a species that recently lost considerable genetic diversity and is now in recovery. Unknown is whether observed patterns are a result of an early stage of incipient speciation, gene flow-selection equilibrium, or reverse speciation causing formerly divergent ecotypes to collapse into a single gene pool.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-016-0788-8) contains supplementary material, which is available to authorized users.

Understanding drivers of forest diversity and structure in managed landscapes: Secondary forests, plantations, and agroforests in Bangladesh

Managed forests in protected area landscapes may extend the conservation functions of nature reserves, but studies comparing biodiversity between managed forest types have not examined the underlying factors that drive existing patterns. We used linear mixed effects models to test the effects of a suite of biotic and abiotic factors on structure and diversity across both plants and birds in complex agroforests, mixed plantations, and mature secondary forests of the same age in northeastern Bangladesh. We measured woody species structure and composition in 18 0.01-ha plots in each forest type across three forest ranges, and conducted bird surveys using 216 point count stations located among the vegetation plots. Tree species richness and diversity, and avian richness in agroforests were higher than, or similar to secondary forests. However, saplings in agroforests and plantations had lower densities and fewer species than secondary forests, and both managed forest types had reduced regeneration. Our results indicate that agroforests have higher potential to conserve late secondary forest species than plantations, due to specific management practices that manipulate light. This work provides quantitative evidence for the utility of traditional agroforests as a conservation tool, even under high levels of human disturbance. Inadequate evidence has been a key limitation to conservation policy planning in landscapes with both high biodiversity and high human density. We find that managed traditional agroforests are an underutilized option in the conservation of protected areas in a landscape that is characterized by human use.

Impacts of Man-Made Structures on Avian Community Metrics in 4 State Parks in Northwestern Arkansas

Avian community metrics often differ between areas with no human disturbance and areas with high levels of human disturbance. However, the relationships between avian community metrics and smaller-scale disturbances are not as clear. Our goal was to investigate if avian abundance, richness, evenness, and diversity differed in areas with and without small-scale human developments. We used fixed-radius 50-m avian point counts to compare points which contained a man-made structure (n = 47), such as a picnic area, road, or campsite to those that did not contain a man-made structure (n = 181) at 4 state parks in Arkansas during 18 May – 7 August 2015. We used paired t-tests to compare points at the park scale and one-way ANOVAs or Kruskal-Wallis tests to investigate differences among the hiking and biking trails within parks. At the park scale, avian abundance (t₃ = -1.44, P = 0.246), richness (t₃ = ˗0.86, P = 0.453), diversity (t₃= 2.02, P = 0.137), and evenness (t₃ =˗0.37, P = 0.733) did not differ between points containing man-made structures and points without man-made structures. Species richness (F1,11 = 5.03, P= 0.047) and diversity (X^2₁ = 4.20, P = 0.040) were higher at points with man-made structures (Simpson’s D mean = 0.13 ± 0.01SE; S mean = 8.99 ± 0.70SE) at Pinnacle Mountain than points without man-made structures (Simpson’s D mean = 0.18 ± 0.03SE; S mean = 7.17 ± 0.47SE); abundance (F₁, ₁₁ = 1.43, P =0.257) and evenness (F₁, ₁₁ = 0.16, P = 0.695) did not differ among points. Within the 3 remaining parks, abundance (F₁,7-9 = 0.11 – 2.59, P = 0.152 – 0.748), richness (χ^2 ₁ = 0.300 – 1.68, P = 0.195 – 0.584), diversity (χ2 = 0.300 – 1.05, P = 0.305 – 0.584; F₁,7 =1.82, P = 0.219) and evenness (F₁,7-9 = 0.35 – 4.28, P =0.077 – 0.570) did not differ between points with and without man-made structures. Given the results of our analyses both at the park scale and within parks, it appears that small-scale man-made disturbances may have limited or no impact on avian community metrics.

普洱市亚洲象栖息地适宜度评价

PDF HTML阅读 XML下载 导出引用 引用提醒 普洱市亚洲象栖息地适宜度评价 DOI: 10.5846/stxb201411142260 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金会资助项目（31172108）；美国内政部鱼和野生动物管理局亚洲象保护基金资助项目（98210-8-G565） Habitat suitability assessment for Asian elephant in Pu'er prefecture in the Yunnan province of China Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:亚洲象（Elephas maximus）属于我国Ⅰ级保护动物，在中国仅分布于云南省西双版纳国家级自然保护区、普洱市的思茅区、澜沧县和江城县，以及临沧南滚河国家级自然保护区。将普洱全境作为研究区域，利用野外调查数据，结合遥感与地理信息系统技术，运用生态位因子分析（ENFA）模型对普洱市亚洲象的栖息地适宜度进行了评价，并预测了适宜栖息地的分布。发现：普洱市亚洲象栖息地的边际值为0.991，表明亚洲象在普洱市境内对环境变量的选择不是随机的；耐受值为0.315，表明亚洲象在普洱市境内生态位较窄，受环境条件的制约。根据模型计算得到的栖息地适宜度指数，将普洱市的亚洲象栖息地分为最适栖息地，较适栖息地，边际栖息地和非栖息地4个等级，面积分别为409.32、574.32、2909.48、38722.32 km2。最适栖息地仅占全市面积的0.96%，而非栖息地占90.86%。利用GIS和Biomapper 4.0生成亚洲象栖息地分布图，发现普洱境内最适栖息地和较适栖息地面积狭小。对最适栖息地、较适栖息地和边际栖息地进行景观格局分析的结果表明，3种类型的栖息地破碎化均十分严重，连通度较低，栖息地内受到较大程度的人类活动的干扰。因此建议在普洱和西双版纳间尽快建立野生动物生态廊道，以加强亚洲象各种群间的交流。 Abstract:The Asian elephant (Elephas maximus) is listed as a first-class protected species in China, and is only distributed in Xishuangbanna, Pu'er, and Lincang prefectures of Yunnan Province. The main threats to the survival of elephants in China were habitat loss and fragmentation. Only 5 elephants were reported in Pu'er in 1996, and currently, there are over 80 elephants belonging to 8 groups living in the region. In this study, we collated 152 elephant occurrence points within the entire Pu'er range in 2010, and assessed habitat suitability for Asian elephant in Pu'er, based on Ecological Niche Factor Analysis (ENFA) of the field survey data. We also predicted the distribution of suitable habitats for elephants in Pu'er. The marginality value obtained from ENFA was 0.992. This result indicated that the deviation of the preferable niche of elephants was different from the average value of the environment, and that elephants chose their habitat non-randomly. The tolerance value was 0.315, which indicated that the niche of Asian elephant was narrow, and that environment indicators restricted the survival of elephants. Results showed that the elephants in Pu'er preferred natural forest with low elevation (<1419 m) and moderate slopes (<14°), as well as areas far from streams and human disturbance (villages and roads). We divided elephant habitat in Pu'er into 4 categories: optimal habitat (409.32 km2), suitable habitat (574.32 km2), marginal habitat (2909.48 km2), and unsuitable habitat (38722.32 km2). The unsuitable habitat accounted for 90.86% of the total area, whereas the optimal habitat occupied only 0.96%. Natural forest is the major vegetation type in optimal (55.6%), suitable (54.55%), and marginal (48.21%) habitats, but it constituted only 33.05% of the unsuitable habitat, indicating that natural forest is the preferred habitat for Asian elephants. According to landscape structure analysis using FRAGSTATS, the mean patch fractal dimension indices (FRAC_MN) for marginal, suitable, and optimal habitats were found to be close to 1, and the meancontiguity indices (CONTIG_MN) were found to be 0.12-0.15. Landscape analysis showed that the optimal, suitable, and marginal habitats all suffered severe fragmentation, low connectivity, and high levels of human disturbance. In comparison with real distribution, the predicted map incorporated some farmlands where Asian elephants forage. The proportion of optimal and suitable habitat in Pu'er is very low, owing to the loss of natural forest and the cultivation of economic plants. It is critical to establish protected areas in the habitat of Asian elephants, in combination with effective conservation measures. In addition, the three main areas of elephant distribution in Pu'er are isolated. It is understood that low connectivity among populations impedes important communication among different population groups. Therefore, it is also necessary to establish and restore ecological corridors to link the current elephant habitats in Pu'er, and to increase their connection with other elephant populations in Xishuangbanna. 参考文献 相似文献 引证文献