Phylogenetic relationships of Strongyloides species in carnivore hosts

Strongyloides stercoralis is a parasitic nematode and a major pathogen responsible for human strongyloidiasis. The presence of this species in the dog population has led to an interest in studying the phylogenetic relationships among Strongyloides spp. in carnivore hosts. In the present study, Strongyloides spp. from various carnivore hosts (raccoon, Japanese badger, Siberian weasel, raccoon dog, masked palm civet, and domestic cat) were sought. Except for civets, Strongyloides spp. were identified in all host species. Based on 18S rDNA sequences, nine OTUs (operational taxonomy units) were identified. Molecular phylogenetic analyses using 18S28S rDNA and mitochondrial cox1 (cytochrome c oxidase subunit 1) sequences clustered them into two groups. The first group (named the stercoralis/procyonis group) was comprised of six OTUs and occurred in cats, raccoon dogs, raccoons (S. procyonis), Siberian weasels, and Japanese badgers and included S. stercoralis from humans and dogs. The second group (named the planiceps group) was made up of Strongyloides spp. from raccoon dogs (two OTUs) and one OTU from Siberian weasels. Subsequent analysis using almost the full-length nucleotide sequences of protein-coding genes in their mitochondrial genomes placed Strongyloides spp. of cats in a sister taxon position to S. stercoralis, whereas S. procyonis from raccoons was more distantly related to them. The presence of Strongyloides spp. from various carnivore hosts, which are close relatives of S. stercoralis, suggests this group of Strongyloides (the stercoralis/procyonis group) essentially evolved as parasites of carnivores, although more data on Strongyloides spp. from primate hosts are needed.     

Comparative landscape genetics of two frugivorous bats in a biological corridor undergoing agricultural intensification

Agricultural intensification in tropical landscapes poses a new threat to the ability of biological corridors to maintain functional connectivity for native species. We use a landscape genetics approach to evaluate impacts of expanding pineapple plantations on two widespread and abundant frugivorous bats in a biological corridor in Costa Rica. We hypothesize that the larger, more mobile Artibeus jamaicensis will be less impacted by pineapple than the smaller Carollia castanea. In 2012 and 2013, we sampled 735 bats in 26 remnant forest patches surrounded by different proportions of forest, pasture, crops and pineapple. We used 10 microsatellite loci for A. jamaicensis and 16 microsatellite loci for C. castanea to estimate genetic diversity and gene flow. Canonical correspondence analyses indicate that land cover type surrounding patches has no impact on genetic diversity of A. jamaicensis. However, for C. castanea, both percentage forest and pineapple surrounding patches explained a significant proportion of the variation in genetic diversity. Least‐cost transect analyses (LCTA) and pairwise G″st suggest that for A. jamaicensis, pineapple is more permeable to gene flow than expected, while as expected, forest is the most permeable land cover for gene flow of C. castanea. For both species, LCTA indicate that development may play a role in inhibiting gene flow. The current study answers the call for landscape genetic research focused on tropical and agricultural landscapes, highlights the value of comparative landscape genetics in biological corridor design and management and is one of the few studies of biological corridors in any ecosystem to implement a genetic approach to test corridor efficacy.     

Shrub encroachment affects mammalian carnivore abundance and species richness in semiarid rangelands

Shrub encroachment due to overgrazing has led to dramatic changes of savanna landscapes and is considered to be one of the most threatening forms of rangeland degradation e.g. via habitat fragmentation. Mammalian carnivores are particularly vulnerable to local extinction in fragmented landscapes. However, our understanding of how shrub encroachment affects mammalian carnivores is poor. Here we investigated the relative sensitivities of ten native carnivores to different levels of shrub cover ranging from low (<5%) to high shrub cover (>25%) in 20 southern Kalahari rangeland sites. Relative abundance of carnivores was monitored along 40 sand transects (5 m × 250 m) for each site.Our results show that increasing shrub cover affects carnivore species differently. African wild cats, striped polecats, cape foxes and suricates were negatively affected, whereas we found hump-shaped responses for yellow mongooses, bat-eared foxes and small-spotted genets with maximum abundance at shrub covers between 10 and 18%. In contrast, black-backed jackals, slender mongooses and small spotted cats were not significantly affected by increasing shrub cover. However, a negative impact of high shrub cover above 18% was congruent for all species.We conclude that intermediate shrub cover (10–18%) in savanna landscapes sustain viable populations of small carnivores.     

Leaf traits and relationships differ with season as well as among species groupings in a managed Southeastern China forest landscape

The relationships among leaf traits often reflect plant adaptation for coping with nutrient resources. However, the seasonal variations in leaf traits and their relationship with soil nutrients are not well understood. We sampled seven major functional traits of thirty trees and nine shrubs (sorted into different plant functional groups, PFGs, based on their growth form, leaf lifespan, and leaf shape) at different seasons in a managed forest plantation of Southeastern China. Both green leaf nitrogen and phosphorus concentrations (N_green and P_green) decreased significantly from spring and summer to autumn, and varied significantly with PFGs (P?<?0.05) at different times of the year. Across all plants, specific leaf area correlated positively with N_green and P_green in spring, summer, and winter, but not in autumn; N resorption proficiency generally correlated positively with N_green in each season, while P resorption efficiency correlated positively with P_green in spring and summer, but not in autumn and winter. Soil nitrogen availability correlated negatively with leaf nutrient traits in some seasons. In conclusion, leaf trait relationships varied among the seasons and among PFGs. Seasonal dynamics of leaf traits as well as soil nutrients?? relations must be considered when exploring plant feedback to soil nutrients.     

Relationships between leaf deciduousness and flowering traits of woody species in the Brazilian neotropical savanna

The relationships between foliage permanence and flowering throughout the year were analyzed in 92 woody species of Cerrado vegetation categorized as either deciduous (DE), semideciduous (SD) or evergreen (EV). Flowering of DE, SD and EV species was investigated via three variables, measured over the course of the year: flowering duration (FLD), calculated as the number of months in flower in each species; flowering distribution (FDI), calculated as the number of species in flower per month; and flowering peak (FPE), defined as the four consecutive months yielding the highest number of species in flower. The months with the highest numbers of species in flower were October (52 species), September (50) and August (49). These months correspond to the period of transition from the dry season to the wet season. In the majority of species studied, seasonal climatic factors were strong enough to induce fruit formation in the dry season and seed dispersal in the following wet season, when sufficient water was available to support germination and plantlet growth. However, significant differences in FLD, FDI and FPE were found among the leaf phenological groups. High FLD in EV species is likely favored by the continuous input of resources from the year-round foliage. In contrast, DE species employ reserves of carbon, water and nutrients to form new leaves and flowers on a crown free of foliage at the end of the dry season. In DE species, their low FLD may reduce the impact of flowering on reserve consumption. SD species showed an intermediate level of foliage persistence, resulting in intermediate FLD values. In addition, SD species exhibited a different pattern of flowering distribution from those of DE and EV species. Many SD species have two flowering periods per year. The first period occurs when the crowns are full of leaves, in the middle of the dry season in June, similar to EV species. The second occurs when only half of the original foliage area is present, near the peak of the dry season in September, similar to DE species. Therefore, despite a strong influence of seasonal climatic conditions on the flowering behavior of DE, SD and EV woody species of Cerrado vegetation, these leaf phenological groups differ significantly in FLD, FDI and FPE.     

Dynamics of a multihost pathogen in a carnivore community

1. We provide the first theoretical analysis of multihost disease dynamics to incorporate social behaviour and contrasting rates of within- and between-group disease transmission. 2. A stochastic susceptible-infected-recovered (SIR) model of disease transmission involving one to three sympatric species was built to mimic the 1994 Serengeti canine distemper virus outbreak, which infected a variety of carnivores with widely ranging social structures. The model successfully mimicked the erratic and discontinuous spatial pattern of lion deaths observed in the Serengeti lions under a reasonable range of parameter values, but only when one to two other species repeatedly transmitted the virus to the lion population. 3. The outputs from our model suggest several principles that will apply to most directly transmitted multihost pathogens: (i) differences in social structure can significantly influence the size, velocity and spatial pattern of a multihost epidemic; and (ii) social structures that permit higher intraspecific neighbour-to-neighbour transmission are the most likely to transmit disease to other species; whereas (iii) species with low neighbour-to-neighbour intraspecific transmission suffer the greatest costs from interspecific transmission.     

Complex effects of scale on the relationships of landscape pattern versus avian species richness and community structure in a woodland savanna mosaic

Landscape pattern metrics are widely used for predicting habitat and species diversity. However, the relationship between landscape pattern and species diversity is typically measured at a single spatial scale, even though both landscape pattern, and species occurrence and community composition are scale‐dependent. While the effects of scale on landscape pattern are well documented, the effects of scale on the relationships between spatial pattern and species richness and composition are not well known. Here, our main goal was to quantify the effects of cartographic scale (spatial resolution and extent) on the relationships between spatial pattern and avian richness and community structure in a mosaic of grassland, woodland, and savanna in central Wisconsin. Our secondary goal was to evaluate the effectiveness of a newly developed tool for spatial pattern analysis, multiscale contextual spatial pattern analysis (MCSPA), compared to existing landscape metrics. Landscape metrics and avian species richness had quadratic, exponential, or logarithmic relationships, and these patterns were generally consistent across two spatial resolutions and six spatial extents. However, the magnitude of the relationships was affected by both resolution and extent. At the finer resolution (10‐m), edge density was consistently the best predictor of species richness, followed by an MCSPA metric that measures the standard deviation of woody cover across extents. At the coarser resolution (30‐m), NDVI was the best predictor of species richness by far, regardless of spatial extent. Another MCSPA metric that denotes the average woody cover across extents, together with percent of woody cover, were always the best predictors of variation in avian community structure. Spatial resolution and extent had varying effects on the relationships between spatial pattern and avian community structure. We therefore conclude that cartographic scale not only affects measures of landscape pattern per se, but also the relationships among spatial pattern, species richness, and community structure, often in complex ways, which reduces the efficacy of landscape metrics for predicting the richness and diversity of organisms.     

Prediction of species composition of plant communities in a rural landscape based on species traits

The species composition of a community is a subset of the regional species pool, and predicting the species composition of a community from ecological traits of organisms is an important objective in ecology. If such a prediction can be made feasible, we could assess the risk of invasion of locally new species (alien species and genetically modified species) into natural communities. We developed and tested statistical models to predict a community’s species composition from ecological traits of the species pool. Various types of communities (forest, meadow, and weed communities) exist in a small area of traditional rural landscape in Japan, and have been maintained by human activities. These communities and the tracheophytes species pool in the 1-km² research area were considered. We used logistic regression and decision-tree analysis to construct predictive models of community species composition based on plant traits, using the presence or absence of species in a community as the dependent variable and ecological traits as independent variables. Plant traits were grouped by cluster analysis, and the average in each trait group was used for model building to avoid multiple collinearity. Statistical prediction models were significant in all communities. About 60–75% of species composition could be predicted from the measured plant traits in forest communities, but 33–56% in the meadow and weed communities. Our results showed the possibility of predicting the species composition of plant communities from the ecological traits of the plant species together with the information on local species pool.     

Invertebrate dispersal and habitat heterogeneity: Expression of biological traits in a seagrass landscape

Seagrass meadows harbour diverse faunal assemblages, but the relative importance of landscapes attributes, settlement processes and biological traits of individual species for recruitment patterns is poorly understood. To quantify the influence of habitat heterogeneity on larval, juvenile and adult post-larval dispersal, invertebrates (> 125 µm) were collected in benthic settlement traps at five occasions (June-August) in three habitats; continuous seagrass, seagrass patches and bare sand. The study was carried out by SCUBA diving in a subtidal (2.5 m depth) seagrass landscape dominated by Zostera marina L. in the Baltic Sea. Traps collected totally > 30 taxa, with non-significant effects of habitat on species richness and total abundance. Total number of invertebrates exhibited strong temporal variability, probably driven by wind-induced bedload and water column transport. Surprisingly, traps located in small (< 12 m²) patches contained on average almost twice as many individuals as traps located in the continuous vegetation. Dominating taxa such as nematodes, copepods, and oligochaetes were found in similar densities across the landscape. In contrast, location within the landscape had strong effects on bivalve settlement and redistribution patterns, resulting in significantly lower densities in continuous vegetation compared to patches and bare sand. A biological trait analysis indicated that semi-mobile taxa with annual protracted direct development, and short-distance dispersal are probably of higher importance for the community assembly process in this environment than long-distance larval dispersal. Results suggest that seagrass landscapes are highly dynamic environments, characterized by time and species-specific effects of landscape attributes on animal dispersal and recruitment. A conceptual model illustrating interactions between settling larvae and landscape heterogeneity is presented.     

Impact of landscape and corridor design on primates in a large-scale industrial tropical plantation landscape

Tropical plantations are rapidly expanding as a source of industrial wood. In Indonesia, such large-scale industrial plantations are generally made of large mono-specific blocks interspersed with natural forest remnants. The extent and biodiversity value of these remnants vary as laws and regulations on their design and management are either unclear, without solid scientific basis or left to the interpretation of private companies responsible for the plantations. Our study area comprises of three Acacia mangium plantations, which have on average 18% of their total area set aside from production and conserved as natural forests. These remnant natural forests may, if appropriately designed and managed, be used to mitigate the negative impact of plantations on biodiversity by providing some degree of connectivity with and between remaining natural forest patches (such as the Tesso Nilo conservation area). We sampled natural vegetation in one and primate diversity in all three plantation sector and examined patterns of primate species richness and abundance with relation to spatial arrangement and dimensions of conservation area, which has been set aside from plantation production. We demonstrate unambiguously the critical importance of a well-connected network of natural forest corridors in the plantation landscape to maintain primates and discuss the potential biodiversity value of natural forest remnants in broad-scale industrial landscapes.     

High variation in foliage and leaf litter chemistry among 45 tree species of a neotropical rainforest community

Distinct ecosystem level carbon : nitrogen : phosphorus (C : N : P) stoichiometries in forest foliage have been suggested to reflect ecosystem-scale selection for physiological strategies in plant nutrient use. Here, this hypothesis was explored in a nutrient-poor lowland rainforest in French Guiana. Variation in C, N and P concentrations was evaluated in leaf litter and foliage from neighbour trees of 45 different species, and the litter concentrations of major C fractions were also measured. Litter C ranged from 45.3 to 52.4%, litter N varied threefold (0.68-2.01%), and litter P varied seven-fold (0.009-0.062%) among species. Compared with foliage, mean litter N and P concentrations decreased by 30% and 65%, respectively. Accordingly, the range in mass-based N : P shifted from 14 to 55 in foliage to 26 to 105 in litter. Resorption proficiencies indicated maximum P withdrawal in most species, but with a substantial increase in variation in litter P compared with foliage. These data suggest that constrained ecosystem-level C : N : P ratios do not preclude the evolution of highly diversified strategies of nutrient use and conservation among tropical rainforest tree species. The resulting large variation in litter quality will influence stoichiometric constraints within the decomposer food web, with potentially far-ranging consequences on nutrient dynamics and plant-soil feedbacks.     

Recent history,current status,conservation and management of native mammalian carnivore species in Great Britain

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Linking traits to species diversity and community structure in phytoplankton

In addition to answering Hutchinson’s question “Why are there so many species?”, we need to understand why certain species are found only under certain environmental conditions and not others. Trait-based approaches are being increasingly used in ecology to do just that: explain and predict species distributions along environmental gradients. These approaches can be successful in understanding the diversity and community structure of phytoplankton. Among major traits shaping phytoplankton distributions are resource utilization traits, morphological traits (with size being probably the most influential), grazer resistance traits, and temperature responses. We review these trait-based approaches and give examples of how trait data can explain species distributions in both freshwater and marine systems. We also outline new directions in trait-based approaches applied to phytoplankton such as looking simultaneously at trait and phylogenetic structure of phytoplankton communities and using adaptive dynamics models to predict trait evolution.     

城市新建景观湖泊浮游植物群落结构及其与环境因子的关系

2019年对南通市中央创新区新建湖泊紫琅湖的浮游植物进行了4个季度的调查,旨在研究典型城市新建景观湖泊的浮游植物群落结构特征及其与环境因子关系。紫琅湖全年共鉴定出浮游植物种类7门186种,春季种类数最多,共6门113种,其中蓝藻门（Cyanophyta）占17.7%,绿藻门（Chlorophyta）占19.5%,硅藻门（Bacillariophyta）占39.8%;夏季种类数最少,共7门43种,其中蓝藻门占32.6%,绿藻门占30.2%,硅藻门占16.3%;冬季和春季则硅藻种类多。从丰度来看,各季节浮游植物组成均以蓝藻为主,冬、夏、秋季蓝藻的丰度分别为（26.81±6.70）×10⁶ ind./L、（12.77±1.02）×10⁶ ind./L和（31.99±10.23）×10⁶ ind./L,显著高于其他藻类（P<0.05）。典范对应分析（CCA）表明透明度、pH、总磷和浊度是与浮游植物群落相关性较强的4个环境因子,其中透明度是最主要的环境因子。冬季和春季浮游植物主要与透明度正相关,夏季主要与总磷和浊度呈正相关,秋季主要与pH呈正相关。紫琅湖的浮游植物优势类群以蓝藻门为主,其中伪鱼腥藻（Pseudoanabaena sp.）为全年唯一的优势藻类（优势度指数分别为Y_冬=0.66,Y_春=0.10,Y_夏=0.16,Y_秋=0.26）。综合营养指数表明湖泊处于轻度富营养水平,浮游植物多样性水质评价表明夏季水体污染相对严重。城市新建景观湖泊紫琅湖营养水平较高、透明度低、浮游植物群落结构波动大,暴发蓝藻水华的可能性较高,研究结果可为城市新建景观湖泊水质改善和健康生态系统的构建提供科学依据。