Intense fishing pressure and climate change are major threats to coastal fisheries. Larimichthys crocea (large yellow croaker) is a long-lived fish, which performs seasonal migrations from its spawning and nursery grounds along the coast of the East China Sea (ECS) to overwintering grounds offshore. This study used length-based analysis and habitat suitability index (HSI) model to evaluate current life-history parameters and overwintering habitat suitability of L. crocea, respectively. We compared both life-history parameters and overwintering HSI between recent (2019) and historical (between 1971 to 1982) to analyze the fishing pressure and climate change effects on the overall population and overwintering phase of L. crocea. In the context of overfishing, the length-based analysis indicated serious overfishing of L. crocea, characterized by reduced catch yield, size truncation, constrained distribution, and advanced maturation in the ECS, namely recruitment bottleneck. In the context of climate change, the overwintering HSI modeling results indicated that climate change has led to decreased sea surface temperature during L. crocea overwintering phase over the last half-century, which in turn led to area decrease and an offshore-oriented shifting of optimal overwintering habitat. The fishing-caused size truncation may constrain the migratory ability and distribution of L. crocea, subsequently led to the mismatch of the optimal overwintering habitat against climate change background, namely habitat bottleneck. Hence, while heavily fishing was the major cause of L. crocea fishery collapse, climate-induced overwintering habitat suitability may have intensified the fishery collapse of L. crocea population. It is important for management to take both overfishing and climate change issues into consideration when developing stock enhancement activities and policy regulations, particularly for migratory long-lived fish that share a similar life history to L. crocea. Combined with China’s current restocking and stock enhancement initiatives, we propose recommendations for future restocking of L. crocea in China.
Sexual dimorphism (SD) is a main source of intraspecific morphological variation, however sexual shape dimorphism (SShD) was long time neglected in evolutionary research. Especially in cold-blooded animal groups only subtle shape differences are expressed between males and females and the selective forces behind it are poorly understood. Crocodile newts of the genera Echinotriton and Tylototriton are highly polymorphic in their reproductive ecology and hence, are a highly suitable model system to investigate potential evolutionary forces leading to SShD differences. We applied 3D geometric morphometrics to the cranial and humerus morphology of nine species of crocodile newts to investigate patterns of SShD in relation to the different mating modes. Trajectories of shape differences between males and females differ in both, cranium and humerus but mating mode does explain differences in SShD trajectories between species only in cranial morphology. Nevertheless, cranial morphology shape differed between the amplecting and circle dancing species. Hence, other selective forces must act here. Variable interspecific allometric trajectories are a potential source of shape differences whereas these trajectories are quite stable for the sexes irrespective of the species.
Many of the species in decline around the world are subject to different environmental stressors across their range, so replicated large-scale monitoring programmes, are necessary to disentangle the relative impacts of these threats. At the same time as funding for long-term monitoring is being cut, studies are increasingly being criticised for lacking statistical power. For those taxa or environments where a single vantage point can observe individuals or ecological processes, time-lapse cameras can provide a cost-effective way of collecting time series data replicated at large spatial scales that would otherwise be impossible. However, networks of time-lapse cameras needed to cover the range of species or processes create a problem in that the scale of data collection easily exceeds our ability to process the raw imagery manually. Citizen science and machine learning provide solutions to scaling up data extraction (such as locating all animals in an image). Crucially, citizen science, machine learning-derived classifiers, and the intersection between them, are key to understanding how to establish monitoring systems that are sensitive to – and sufficiently powerful to detect –changes in the study system. Citizen science works relatively ‘out of the box’, and we regard it as a first step for many systems until machine learning algorithms are sufficiently trained to automate the process. Using Penguin Watch (www.penguinwatch.org) data as a case study, we discuss a complete workflow from images to parameter estimation and interpretation: the use of citizen science and computer vision for image processing, and parameter estimation and individual recognition for investigating biological questions. We discuss which techniques are easily generalizable to a range of questions, and where more work is needed to supplement ‘out of the box’ tools. We conclude with a horizon scan of the advances in camera technology, such as on-board computer vision and decision making.
1.In this study, the dominant woody plants in different degraded background plots in Puding, Guizhou Province were selected as the research objects. Six leaf functional traits(LT, LA, SLA, LDMC, LTD, Chlc) were measured to analyze the effects of soil characteristics on the leaf functional traits of vegetation in the region. 2.We observed that under the degraded environment of karst area, the plant leaves tended to increase, with the most significant change in the returned land; There were significant differences in plant traits under burning,burning felling and returning farmland, with the largest change range of LA, LTD and SLA, which could reach 121.90%, 118.08% and 86.00% respectively in the corresponding sample plots. 3.In the degraded plots, the leaf traits were significantly different among tree, shrub and liana species. In general, the interspecific variation of shrub and liana species was higher than that of tree species, and the community was in the early and middle stage of succession. 4.Soil properties under different degradation background were quite different,and there was a significant correlation between soil properties and vegetation leaf functional properties. Soil depth, soil nutrients and soil humidity were the key soil characteristic factors of plant leaf functional properties. 5.The results showed that the leaf traits of plant in degraded area showed large LA,small LT, low SLA and LTD, high LDMC and low Chlc, which tended to develop drought character combination. This paper reveals the internal differentiation succession law of degraded karst secondary forest in central Guizhou and provides scientific basis for the management and biodiversity protection of karst secondary forest.
Warming climates provide many species the opportunity to colonise newly-suitable regions at higher latitudes and elevations. Despite becoming warmer, higher latitudes and elevations nevertheless offer novel climatic challenges, such as greater thermal variability and altered frequency of weather events, and these challenges exert selection on expanding populations. However, high gene flow and genetic drift during the expansion phase may limit the degree to which species can adapt to novel climatic conditions at the range front. Here we examine how landscape topographic complexity influences the opportunity for local adaptation to novel conditions during a range shift. Using RAD-seq data, we investigated whether elevation, latitude, climatic niche differentiation, and gene flow across a complex landscape were associated with signatures of adaptation during recent range expansion of the damselfly Ischnura elegans in Northeast Scotland. Our data revealed two distinct routes of colonisation, with admixture between these routes resulting in increased heterozygosity and population density. Expansion rates, assessed as directional rates of gene flow, were greater between more climatically similar sites than between climatically divergent sites. Significant genetic structure and allelic turnover was found to emerge near the range front at sites characterised by high elevation, low directional gene flow, and high spatial differentiation in climate regimes. This predictive combination of factors suggests that landscape complexity may be a prerequisite for promoting differentiation of populations, and providing opportunities for local adaptation, during rapid or contemporary range shifts
Aim: Higher elevation habitats contribute substantially to global biodiversity. Nevertheless, we know comparatively little about how diversity patterns differ among alpine and montane communities across different mountain ranges. Here, we characterized the realized niche space of American seed plants to ask whether or not montane or alpine community compositions define climatically distinct species pools at this regional scale. Location: Americas. Time Period: Contemporary. Major taxa studied: Seed plants. Methods: We assembled a niche model dataset of 72,372 American seed plants based on digitized and georeferenced specimen records. We used this dataset to quantify occupied abiotic niche space with regards to temperature, precipitation, and elevation. This approach further permitted differentiation of higher-elevation specialists (i.e., ranges centered at high elevations) from generalists (i.e., ranges centered at lower elevations but extending into mountain areas). Results: Montane communities did not differ from the regional species pool in terms of richness patterns, occupied climatic niche space, or niche breadth. In contrast, alpine communities were characterized by a bimodal latitudinal diversity gradient, drastically reduced climatic niche space, and broader temperature but narrower precipitation niche breadth. Alpine generalists further showed statistically significant differences in temperature, but not precipitation, niche breadth from both alpine specialists and lowland taxa. We also highlight non-alpine species whose climatic niche space otherwise overlapped with that of alpine plants. These species were geographically concentrated in the southern US and Mexico, tended to have a greater fraction of their ranges in frost-exposed mountain foothills, and less of their range in lowland, frost-free, areas, compared to other non-alpine species. Main conclusions: These results suggest that ecological and physiological barriers, rather than dispersal limitation might better explain alpine community assembly and that alpine, but not montane, communities form a climatically distinct species pool in the Americas.
Maintenance of a desirable mixture of shrubs and grasses is a key issue in sustainable grazing management. The aim of this study was to explore the effect of long-term sheep grazing on desert steppe shrubs. Based on a long-term controlled sheep stocking rate experiment in a desert steppe of north China, combined with long-term random sampling monitoring of above-ground vegetation standing crop (14 years) and short-term systematic sampling monitoring of vegetation cover and individual characteristics of shrubs (3 years), we analyzed plant community changes, the current situation of shrubs and the response of individual shrub characteristics to stocking rate. We found that low stocking rates have increased the cumulative above-ground standing crop of shrubs and herbaceous plants, but the cumulative above-ground standing crop of shrubs under high grazing rates tends to be flat. The cover and height of four shrub species generally showed a decrease with increasing stocking rate, while the response of the four shrubs to the stocking rate gradient varied. Among four shrub species, Artemisia frigida was the most sensitive to stocking rate, followed by Ceratoides latens and Caragana microphylla, while Kochia prostrata was relatively insensitive to stocking rate. These results suggest that grassland managers can use an appropriate stocking rate to maintain desirable plant community composition and configuration in the temperate grassland.
Aim: Wildlife and their interaction human or human-wildlife conflict, though reported throughout human prehistory, its severity and complexity have increased in recent years. The Hindu Kush Himalaya region, rich and biodiversity and known as roof of the world have gained recognition for many conservation success but also with increasing trends of human-wildlife conflict. But, they are sparsely documented and the severity of its impacts are not known for the region. Hence, we present a systematic review on human-wildlife conflict from the roof of the world. Methods: We followed the systematic literature review (SLR) approach of qualitative content analysis, using Search, Appraisal, Synthesis, and Analysis (SALSA) framework and also used VOSViewer for spatial and network analysis.. Results: Our results based on 240 peer-reviewed articles till 2019 showed 57% increase of publications in the last decades but with disproportionate geographical and thematic focus. About 82% of the research reported cases are from protected area with large carnivores and mega-herbivores as major causes of the conflict. About 53% of the studies were questionnaire-based household and the results highlight habitat disturbance through land cover change, urbanization, and human population increase as major drivers of human-wildlife conflict. Traditional management techniques like guarding and fencing along with improvement in plans and policies have been reported. Our analysis of 681 keywords revealed prominent focus on ‘human-wildlife conflict’, ‘Nepal’, ‘Bhutan’, ‘Snow Leopard’ and ‘Leopard’ indicating the issue are linked with these species and countries. The involvement of 640 authors from 36 countries indicates increasing interest and Nepal and India are playing key role from the region. Main conclusions: There is spatial variation in research with limited regional and transboundary focus. Attention is needed on understanding the pattern of interactions including meso animals along with improved management interventions through integrated and transboundary cooperation for tackling the issue.
Identifying factors that influence sea otter (Enhydra lutris) population density can provide insight into why it varies spatially and temporally and when a recovering population has reached an equilibrium density because of food resources (i.e., carrying capacity K). Although food availability is widely recognized as an important extrinsic factor affecting sea otter density, how do we determine when a population has reached K? The goal of this study was to estimate K for Simpson Bay, Alaska by measuring the abundance of edible bivalves, the primary prey for sea otters for over 40 years. We then compared prey abundance and estimated replacement rate (i.e., the mean age of bivalves predated by sea otters) to estimated annual prey consumption based on the mean population density for the past 18 years. On average, 110 adult sea otters (5.2 km−2) have occupied Simpson Bay annually since 2001 consuming an estimated 176,660 kg of bivalves. The total mass (standing stock) of the major bivalves (predominately butter clams and stained macomas) was 785,730 kg, so adult sea otters consumed about 22% annually. Based on these observations and calculations, the estimated annual number of sea otters occupying Simpson Bay appears to be at or near K based on the replacement rate of food resources. However, other intrinsic (e.g., male territoriality and emigration) and extrinsic (e.g., predation, disease, human-related mortality) factors may influence equilibrium density, which varies spatially and temporally, resulting in a mosaic of subpopulations with different densities, rates of growth and discontinuous distributions. Understanding the balance among these factors may be one of the most challenging ecological questions for sea otter conservation and management as populations recover from their range-wide decimation during the Maritime Fur Trade in the late 18th and 19th centuries
1. The Tea Bag Index (Keuskamp et al. 2013) has been developed to allow worldwide comparable data on litter decomposition and has become an important part of several citizen science projects. This commentary shows that it is unsuitable for assessing total decomposition in most environments as it does not account for the role of macrofauna in the decomposition process. 2. Tea bags were placed following the standardised protocol in old growth forest in Borneo (Sabah, East Malaysia). 3. The results shows that more than half of the bags were attacked by termites and they tended to remove the majority of the tea, rendering the Tea Bag Index incalculable. 4. The Tea Bag Index can measure the microbial component of decay, but will significantly underestimate total decay rates in most environments. This method will not give an accurate estimate of decomposition in most biomes.
Study of the carnivore guild is the key to understand quantitative relationship between members of the carnivore community. The aim of the study was to investigate diversity, abundance and population structure of the mongoose in Nech Sar National Park. Ecological data collection on mongoose species has been carried out from September 2017 to August 2018 in Nech Sar National Park (NSNP). Based on the habitat type and topography of NSNP, 10 transects, each of 4-5 km long were sampled to traverse the major habitat types in the park. Line transect distance sampling methodology was used to determine abundance and population status. DISTANCE (Version 6.0, Release 2) Software was used for density and abundance estimation of mongoose populations. The key to distance sampling analyses is to fit a detection function to the observed distances, and hence, the key functions hazard rate + hermite polynomial, unform + cosine polynomial and half normal + hermite polynomial models were chosen over the others on the basis of best fit. Three species of mongoose namely- Egyptian mongoose (Herpestes ichneumon,) Slender mongoose (Herpestessanguineus) and White tailed mongoose (Ichneumiaalbicauda) were identified in the study. The overall density of mongoose in the study area was 2.3048+0.16070 individuals/km2 with population estimate of 943+85.593 individuals. Based on season and habitat type, density and abundance estimates showed variation (P<0.05). However, species composition between seasons and habitats was the same. The highest species diversity (H=1.197) was recorded in bushland habitat. The population was female-baised with 1:1.171 and 1:1.59, male to female ratio during wet and dry seasons, respectively. Adult to young (subadult and juvenile) ratio was1.05:1 and 0.94: 1 during wet and dry seasons, respectively. Further researches on other ecological parameters viz. behavior, feeding habit and activity pattern are important to acquire a complete picture about mongoose ecology in the park.
Light-regime variability is an important environmental factor which shapes a forest community. So far, none focused on the phylogenetic pattern of plant light receptors, which reflects how genes’ evolution influences the coexistence of species in a community. In this study, we analyzed community phylogenetic structure of the south subtropical forest by sequences of plant blue light receptor cryptochrome (CRY) and compared the results of DNA barcodes. Patterns of community assembly was estimated by net relatedness index (NRI) and nearest taxon index (NTI). We found that CRY showed quite different phylogenetic structure as compared to DNA barcoding results, all habitats displayed consistent phylogenetic structure patterns, suggesting a convergent evolution of light sensing system of plant in local adaptation. Also, both NRI and NTI values increased through the time, indicating that the phylogenetic structure of tree community became more overdispersion as succession proceeds; phylogenetic closely-related species tended to co-occur and environmental filtering played a more important role in the community assembly. Furthermore, phylogenetic patterns were more clustering in upper canopy layers, and NTI values of all canopy layers were above zero, suggesting that phylogenetically related species tended to coexist and adapted to similar light conditions.
1. 1. Thermal imaging technology is a developing field in wildlife management. Most thermal imaging work in wildlife science has been limited to larger ungulates and surface-dwelling mammals. Little work has been undertaken on the use of thermal imagers to detect fossorial animals and/or their burrows. Survey methods such as white-light spotlighting can fail to detect the presence of burrows (and therefore the animals within), particularly in areas where vegetation obscures burrows. Thermal imagers offer opportunity to detect the radiant heat from these burrows, and therefore the presence of the animal, particularly in vegetated areas. Thermal imaging technology has become increasingly available through the provision of smaller, more cost-effective units. Their integration with drone technology provides opportunities for researchers and land managers to utilise this technology in their research/management practices. 2. We investigated the ability of both consumer (AUD$65,000) mounted on drones to detect rabbit burrows (warrens) and entrances in the landscape as compared to visual assessment. 3. Both types of imager and visual inspection detected active rabbit warrens when vegetation was scarce. The presence of vegetation was a significant factor in detecting entrances (P<0.001, α=0.05). The consumer imager did not detect as many warren entrances as either the professional imager or visual inspection (P=0.009, α=0.05). Active warren entrances obscured by vegetation could not be accurately identified on exported imagery from the consumer imager and several false-positive detections occurred when reviewing this footage. 4. We suggest that the exportable Hz rate was the key factor in image quality and subsequent false positive detections. This feature should be considered when selecting imagers. Thermal imagers are a useful additional tool to aid in identification of entrances for active warrens and professional imagers detected more warrens and entrances than either consumer imagers or visual inspection.
Accurate determination of animal diets is difficult. Methods such as molecular barcoding or metagenomics offer a promising approach, allowing quantitative and sensitive detection of different taxa. Here we show that rapid and inexpensive diet quantification is possible through metagenomic sequencing with the portable Oxford Nanopore Technologies (ONT) MinION. Using an amplification-free approach, we profiled the stomach contents from 24 wild-caught rats. We conservatively identified diet items from over 50 taxonomic orders, ranging across nine phyla, including plants, vertebrates, invertebrates, and fungi. This highlights the wide range of taxa that can be identified using this simple approach. We calibrated the accuracy of this method by comparing the characteristics of reads matching the ground-truth host genome (rat) to those matching diet items, and show that at the family-level, taxon assignments are approximately 97.5% accurate. Some inaccuracies may arise from database biases; we suggest a way to mitigate for database biases when using metagenomic approaches. Finally, we implemented a constrained ordination analysis and show that we can identify the sampling location of an individual rat within tens of kilometres based on diet content alone. This work establishes proof-of-principle for long-read metagenomic methods in quantitative diet analysis. We show that diet content can be quantified even with limited expertise, using a simple, amplification free workflow and a relatively inexpensive and accessible next generation sequencing method. Continued increases in the accuracy and throughput of ONT sequencing, along with improved genomic databases, suggests that a metagenomic approach for quantification of animal diets will become an important method in the future.
White-tailed bumblebee species, Bombus cryptarum, B. lucorum, B. magnus and B. terrestris are known to be very similar in their morphological characters across the majority of their ranges. This hampers assessment of their status and trends because reliable identification is difficult. In this study, we use a combination of characters and methods to assess how ecologists and citizen scientists can reliably and quickly separate these four species occurring in the Netherlands. Bumblebees (queens, workers and males) were sampled from 10 locations across the Netherlands and specimens were identified based on COI sequence data. Next, the same specimens where scored for morphological traits. We show that a combination of easy to recognise characteristics can separate some specimens of the species depending on caste and sex. Bombus magnus males and queens and B. lucorum males were most reliably separated from the other species using morphological characters. Workers of all four species cannot be separated completely using morphological characters alone. This is the first time standard morphological characters and ecological data has been used to study the differences between the white-tailed bumblebees in the Netherlands. Based on our findings we need to conclude that the status of these bumblebee species in the Netherlands is uncertain due to possible misidentifications in the past and present. People who wish to work with these species should be careful in species identification based on morphology.
Senna didymobotrya is invasive native flowering shrubs mainly grow in Africa. Climate change thought to facilitates the introduction and spread of invasive alien species. The present study aimed at examining the present and future invasion of S. didymobotrya under the changing climatic using species distribution modeling. The mean AUC and TSS value of the model was (95%) and (81%), respectively, which put the model under an excellent category. Our result showed under the current climatic conditions 18.11% of the continent is suitable for S. didymobotrya invasion. Eastern African countries are found the most suitable habitat for S. didymobotrya invasion followed by southern African countries. The total highly suitable area for the species is 3.4% and 3.17% in 2050s under RCP4.5 and RCP8.5, respectively. In the 2070s, the highly suitable area is predicted as 3.18 % and 2.73% in RCP4.5 and RCP8.5, respectively. An area with the category of low to moderate suitability under RCP 4.5 and RCP8.5 in the 2050s is projected as 17.4 % and 20.5 % and this area is increased in the 2070s to19.11% and 22.82 for the RCP 4.5 and RCP 8.5, respectively. The results of this study showed a substantial contraction in the high suitability areas, but a large increase in the low and moderately suitable habitat. Despite the contraction in highly suitable areas, countries which are found suitable in the present climatic condition remains suitable for S. didymobotrya establishment. Our ensemble predicted a significant increase in the vulnerability of habitat for invasion under the future climatic scenarios. Our study suggests the future biodiversity conservation strategy and policy direction should focus on the means and strategy of limiting the rate of expansion of invasion and distribution in different ecosystem types, hence reduce the expected harm in the ecosystem services.
We argue the advantages of field-based learning experiences for undergraduates, the societal imperative for training the next generation of field biologists, and the opportunity to increase the reach of field education dictate that we must meet the challenges of delivering field experiences in the context of a distanced educational environment. We report on our experiences as faculty and students in a spring 2020 Field Ornithology course adapted for remote delivery with an example of a student-centered framework for supporting independent field study. Feedback from students and instructors in this course indicate that remote field instruction is both possible and desirable. We suggest that an instruction model involving guided, independent field study can yield strong learning outcomes and promote self-directed inquiry. Based on reflections of the challenges and successes of our experiences, we provide an prompts for a for assessing the feasibility and desirability of proceeding with field-based education in a distanced environment with an emphasis on supporting student success.
Scientific activities including university classes, wet lab research activities, fieldwork, and seminars/conferences have been cancelled in response to the ongoing COVID-19 pandemics. While the public health priority was to contain and mitigate the outbreak, the science sector swiftly adopted technologies to stay connected and continue the scientific activities as much as possible. Creativity, ingenuity, and resilience abound in the science community manifested in successful examples of truly global activities such as seminar series and conferences. While these platforms were initially concerned with maintaining the continuum of science education and dissemination, they attracted participants beyond the boundaries of their respective institutions and countries and thereby increased the equity. While the communities and countries are easing the societal restrictions and the scientific community returns to on-site work, it is important to learn the lessons and ensure equity in science education and dissemination moving forward.