We use the InVEST model and five periods of land use data from 1980 to 2020 to assess the habitat quality of the Ningxia Hui Autonomous Region in western China, which has characteristics of a typical fragile ecosystem. We further analyze the spatial and temporal characteristics of habitat quality evolution and its relationship with land use and landscape pattern indices to explore the close relationship between regional habitat quality changes and human natural resource conservation and utilization.The research results show that the overall habitat quality of Ningxia Hui Autonomous Region was stable and at a moderate level during the 40 years from 1980 to 2020; Habitat patches with low, high and very high quality occupy a larger proportion of the area, followed by very low and moderate levels. There was a significant spatial aggregation of high and low habitat quality in Ningxia, with high values usually distributed in the northern and southern areas with good natural conditions and low values distributed in areas with frequent human activities and poor natural conditions. The decrease in habitat quality in Ningxia was mainly due to the expansion of cultivated land and construction land, the increase in landscape fragmentation and the resulting decrease in connectivity. On the other hand, due to the implementation of ecological protection measures, such as the project of returning farmland to pasture and grass to forest, the quality of habitats in Ningxia increased. The conclusions of this study support the idea that the conservation of habitat quality in ecologically fragile areas should fully preserve the original natural habitats and reduce the interference of human activities. At the same time, targeted ecological protection policies should be developed to restore the areas where the habitat quality has been damaged and ultimately maintain the stability of biodiversity and ecosystems in ecologically fragile areas.
Plant and soil biodiversity can have significant effects on herbivore resistance mediated by plant metabolites. Here, we disentangled the independent effects of plant diversity and soil legacy on constitutive and herbivore-induced plant metabolomes of three plant species in two complementary microcosm experiments. First, we grew plants in sterile soil with three different plant diversity levels. Second, single plant species were grown on soil with different plant diversity-induced soil legacies. We infested a subset of all plants with Spodoptera exigua larvae, a generalist leaf-chewing herbivore, and assessed foliar and root metabolomes. Neither plant diversity nor soil legacy had significant effects on overall foliar, root, or herbivore-induced metabolome composition. Herbivore-induced metabolomes, however, differed from those of control plants. We also detected 139 significantly regulated metabolites by comparing plants grown in monocultures with conspecifics growing in plant or soil legacy mixtures. Moreover, plant-plant and plant-soil interactions regulated 141 metabolites in herbivore-induced plants. Taken together, plant diversity and soil legacy independently alter the concentration and induction of plant metabolites, thus affecting the plant's defensive capability. This is a first step towards disentangling plant and soil biodiversity effects on herbivore resistance, thereby improving our understanding of the mechanisms that govern ecosystem functioning.
1. Passive Acoustic Monitoring is emerging as a solution for monitoring species and environmental change over large spatial and temporal scales. However, drawing rigorous conclusions based on acoustic recordings is challenging, as there is no consensus over which approaches and indices are best suited for characterizing marine acoustic environments. 2. We present an alternative to the use of ecoacoustic indices and describe the application of multiple machine learning techniques to the analysis of a large PAM dataset. We combine pre-trained acoustic classification models, dimensionality reduction, and random forest algorithms to demonstrate how machine-learned acoustic features capture different aspects of the marine environment. We processed two PAM databases and conducted 13 trials showing how acoustic features can be used to: i) discriminate between the vocalizations of marine mammals, beginning with high-level taxonomic groups, and extending to detecting differences between conspecifics belonging to distinct populations; ii) discriminating amongst different marine environments; and iii) detecting and monitoring anthropogenic and biological sound sources. 3. Acoustic features and their UMAP projections exhibited good performance in the classification of marine mammal vocalizations. Most of the taxonomic levels investigated here could be classified using the UMAP projections, apart from species that were underrepresented. Both anthropogenic (ships and airguns) and biological (humpback whales) sound sources could also be identified in field recordings. 4. We argue that acoustic feature extraction, visualization, and analysis allows the retention of most of the environmental information contained in PAM recordings, overcoming the limitations encountered when using ecoacoustics indices. Acoustic features are universal, permitting comparisons of results collected from multiple environments. Our approach can be used to simultaneously investigate the macro and micro characteristics of marine soundscapes, with a more objective method and with far less human effort.
Background and aims High-intensity grazing in Mongolian grasslands has led to the general deterioration of biodiversity and ecosystem functioning. Abundant evidence shows that grazing affects the structure and function of grassland ecosystems, especially under overgrazing. Methods We examined the effects of three grazing intensities (0, 1.92, and 3.08 sheep ha-1 a-1) on plant commu-nities, plant and soil C, N and P contents, and plant and soil C:N:P stoichiometry in a desert grassland in different years. Results Grazing did not affect plant coverage, richness, or N:P, and the plant community biomass, litter bio-mass and C:N and C:P were highest under a zero grazing intensity. Soil C:N changed with the year and grazing intensity. However, soil C:P and N:P were higher in 2018 than in 2016 and 2017. Conclusions Our study suggested that grazing promoted the flow of N between plants and the soil, especially at 3.08 sheep ha-1 a-1. Under grazing stress, plants maintained the potential for compensatory growth. Further-more, N was shown to be the limiting fertilizer component for plants growing in this area among the three grazing intensities.
The encroachment of freshwater territories by invasive species is a global issue with its associated co-existence, displacement and facilitation of native species. The blackchin tilapia, Sarotherodon melanotheron is one of the most successful biological invasive species. Data on its apparent ecological consequences on native species are rare in Nigerian inland waters. Based on stomach contents analyses, diets, feeding strategies, and dietary niche breadths of two sympatric invasive S. melanotheron and native Nile tilapia Oreochromis niloticus populations in a tropical domestic water supply were assessed for possible convergence. Both species exhibited generalist feeding strategies subsisting mostly on algae but fish eggs and larvae were conspicuous preys of S. melanotheron. Dietary niche of S. melanotheron was wider than that of O. niloticus. Dietary niche overlap was high and significant between these sympatric species. These findings imply that competitive feeding interactions-including predations on vulnerable early life stages may potentially promote invasion success of S. melanotheron in Eleiyele Reservoir.
Phytoplankton plays a fundamental role in the ecology of ocean systems and is the key player in the global carbon cycle. At a time of global warming, understanding the mechanisms of its adaptation to temperature is therefore of paramount importance. Cosmopolitan planktonic species abundant in different marine environments provide both a unique opportunity and an efficient methodological tool to study the genomic bases of their adaptation. This is the case for the eukaryotic picoalga Bathycoccus prasinos, whose genomic variability we chose to study in temperate and polar oceanic waters. Using multiple metagenomic datasets, we found that ~5% of B. prasinos genomic positions are variable, with an overwhelming majority of biallelic motifs. Cold and temperate waters are clearly associated with changes in variant frequencies, whereas in transitional waters we found more balanced polymorphism at most of these positions. Mesophilic and psychrophilic gene variants are distinguished by only a few amino acid changes located at positions critical for physical and functional protein properties. These results provide new information on the genomic diversity of a cosmopolitan eukaryotic planktonic species and suggest “minimal mutational strategies” related to the properties of specific proteins at different temperatures.
For more than three decades, the Asian turtle crisis has resulted in the decline of every native species in China. For some species, such as the yellow pond turtle (Mauremys mutica), wild populations have dwindled to near functional extinction. Previous studies show there is deep genetic divergence of M. mutica sensu lato between populations north and south of the Pearl River Drainage but no data to show if phylogeographic structure occurs within these two main types. In this study, we found clear phylogeographic structure. In northern types, we found two main clades, corresponding to mainland China and island clades (Taiwan and Yaeyema Islands) with uncorrected p values of 0.00-2.0% divergence in our 2353 bp concatenated mtDNA data set. For the southern types, we found three main clades corresponding to Hainan, Mainland (Vietnam/Guangxi) and the Annam pond turtle (Mauremys annamensis) with divergence ranging from 1.0-1.8% among these three groups. Moreover, the identification of northern and southern types by phenotype was roughly 98% accurate, which, coupling with the deep genetic divergence in mtDNA (5.5-6.7%) and in the 6056 bp nuDNA data set (0.16-0.37%) provide sufficient evidence for northern M. mutica to be an independent species, and individuals from the southern clade should be regarded as subspecies of M. annamensis. Finally, we provide the most comprehensive database to date which can be used to determine the region of origin for captive stock. Making the large captive populations of M. mutica, under the right conditions, potentially valuable for restocking or augmentation of wild populations.
Plants in suburban forests of eastern North America face the dual stressors of high white-tailed deer density and invasion by nonindigenous plants. The combination of chronic deer herbivory and strong competition from invasive plants could alter a plant’s stress- and defense-related secondary chemistry, especially for long-lived juvenile trees in the understory, but this has not been studied. We measured foliar total antioxidants, phenolics, and flavonoids in juveniles of two native trees, Fraxinus pennsylvanica (green ash) and Fagus grandifolia (American beech), growing in six forests in the suburban landscape of central New Jersey, USA. The trees grew in experimental plots that had been subject for 2.5 years to factorial treatments of deer access/exclosure X addition/no addition of the nonindigenous invasive grass Microstegium vimineum (Japanese stiltgrass). As other hypothesized drivers of plant secondary chemistry, we also measured non-stiltgrass herb layer cover, light levels, and water availability. Univariate mixed model analysis of the deer and stiltgrass effects and multivariate structural equation modeling (SEM) of all variables showed that both greater stiltgrass cover and greater deer pressure induced antioxidants, phenolics, and flavonoids, with some variation between species. Deer were generally the stronger factor, and stiltgrass effects were most apparent at high stiltgrass density. SEM also revealed that soil dryness directly increased the chemicals; deer had additional positive, but indirect, effects via influence on the soil; in beech PAR positively affected flavonoids; and herb layer cover had no effect. Juvenile trees’ chemical defense/stress responses to deer and invasive plants can be protective, but also could have a physiological cost, with negative consequences for recruitment to the canopy. Ecological implications for species and their communities will depend on costs and benefits of stress/defense chemistry in the specific environmental context, particularly with respect to invasive plant competitiveness, extent of invasion, local deer density, and deer browse preferences.
Comparing life history traits among populations that have been separated genetically for several hundred thousand years, but live in similar habitats on different continents, may help us understand how ecological and anthropomorphic factors shape life histories. We compared patterns of growth in body length and mass, and the influence of population density, habitat quality (NDVI), and reproduction on age-specific length and mass of male and female brown bears between Alberta, Canada, and Sweden. We found that Swedish females were significantly smaller in both length and mass than Alberta females. Swedish females also reached primiparity earlier and at a smaller mass and length. However, there were no continental differences in the patterns of growth in males. We found strong positive effects of NDVI, but only weak negative effects of population density on female mass and length in both areas. Generally, especially mass of Alberta females was more strongly affected by NDVI and density than for Swedish females. Reproduction had stronger negative effects on female mass in Alberta than in Sweden. We found no effects of NDVI and population density on male mass and body length in both areas. The larger variation in female growth and size between the areas, in contrast to males, may be related to differences in female reproductive investment due to differences in population trends, i.e., earlier reproduction in increasing populations or populations below carrying capacity, or to different selection pressures in the past, potentially due to human persecution. Swedish females exhibited characteristics typical of increasing populations, whereas Alberta females exhibited characteristics typical of stable or decreasing populations. The difference in reproduction investment means that Swedish bears can be harvested at higher rates, whereas Alberta bears must be managed more conservatively.
The Timber Rattlesnake (Crotalus horridus) has a large distribution spanning much of the eastern United States. Because temperature, habitat type, prey composition and abundance, and a variety of other factors may dictate reptile behavior, populations of conspecific species may exhibit behavioral differences across latitudinal and elevational gradients. Using radio telemetry, we tracked 10 adult Timber Rattlesnakes (7 males, 3 females) from May 2016 to June 2017 in southeastern Louisiana to examine the spatial ecology of male and non-gravid female snakes. Mean annual and seasonal home ranges of non-gravid female Timber Rattlesnakes were not statistically different from that of males. Mean seasonal home range sizes and average distances travelled of both sexes was smallest in winter, and had a general increasing trend beginning in spring with a peak in fall. These increases seemed to coincide with the breeding season, taking place from early July until the end of November. Comparison of this study with other studies throughout its distribution could have implications towards future management of conservation for other southern populations of Timber Rattlesnakes.
The Yunnan-Guizhou Plateau (YGP) is characterized by the distinctive isolated habitat of limestone Karst Islands and features the Wumeng Mountains (Mts), which divide the YGP into the two Plateaus of Yunnan and Guizhou. This study aims to assess the effects of past geographic and environmental isolation and climate fluctuation on the flora distribution in the YGP. To this effect, we analyzed the phylogeographical pattern and genetic structure for Myrica nana, a vulnerable species endemic to the YGP, based on chloroplast and nuclear ribosomal DNA sequence. The results suggest that the genetic and haplotype network structures are divided into at least two groups—cpDNA haplotype H2 (or nrDNA haplotypes h1, h2, and the native haplotype) mainly distributed to the east of the Wumeng Mts, and cpDNA haplotype H1 and haplotypes H3–H10 (or nrDNA haplotype h3) distributed to the west of the Wumeng Mts. A deep genetic split was noted within the two groups to reach 25 steps, especially for the cpDNA fragment variation. The east–west divergence reveals the existence of a natural geographical isolation boundary in the form of the Wumeng Mts, which divides the YGP into the Yunnan and Guizhou Plateaus. Therefore, there existed at least two glacial refugia during the Quaternary glacial period, along with a genetic diversity center, and at least two large geographic protection units for the vulnerable species of M. nana, distributed throughout the eastern and western sides of the Wumeng Mts. This study not only clarifies that the phylogeographical pattern and genetic structure for M. nana can be attributed to geographic and environmental isolation and climate fluctuation, but it also proposes an effective strategy to protect vulnerable species and the important wild flora of the YGP.
There is much concern about disruption of endocrine physiology regulated by steroid hormones in humans, other terrestrial vertebrates and fish by industrial chemicals, such as bisphenol A, and pesticides, such as DDT. These endocrine-disrupting chemicals influence steroid-mediated physiology in humans and other vertebrates by competing with steroids for receptor binding sites, disrupting diverse responses involved in reproduction, development and differentiation. Here I discuss that due to evolution of the progesterone receptor (PR) and mineralocorticoid receptor (MR) after ray-finned fish and terrestrial vertebrates diverged from a common ancestor, each receptor evolved to respond to different steroids in ray-finned fish and terrestrial vertebrates. In elephant shark, a cartilaginous fish, ancestral to ray-finned fish and terrestrial vertebrates, both progesterone and 17,20b-dihydroxy-progesterone activate the PR. During the evolution of ray-finned fish and terrestrial vertebrates, the PR in terrestrial vertebrates continued responding to progesterone and evolved to weakly respond to 17,20b-dihydroxy-progesterone. In contrast, the physiological progestin for the PR in zebrafish and other ray-finned fish is 17,20b-dihydroxy-progesterone, and ray-finned fish PR responds weakly to progesterone. The MR in fish and terrestrial vertebrates also diverged to have different responses to progesterone. Progesterone is a potent agonist for elephant shark MR, zebrafish MR and other fish MRs, in contrast to progesterone's opposite activity as an antagonist for aldosterone, the physiological 2 mineralocorticoid for human MR. These different physiological ligands for fish and terrestrial vertebrate PR and MR need to be considered in applying data for their disruption by chemicals in fish and terrestrial vertebrates to each other.
1. Latitudinal diversity gradient (LDG) is the increase in species richness towards the equator and is one of the most consistent patterns in biogeography, where current and historical processes contribute to shape the pattern. 2. Despite that LDG patterns have been described for some insects, the underlying mechanisms associated with community assembly and diversification along modern latitudinal diversity gradient pattern remain unknowledge for many groups. 3. Odonata is an old order of insects that originated during the Carboniferous and has diversified through different eras. Here, we defined co-occurrence based on the presence in ecoregions and 1°×1° grid cells of Odonata species in North America NA, to address their species richness, phylogenetic structure, and species diversification rate along the latitudinal gradient. 4. For the whole order, we found the highest species richness at mid-latitudes, while phylogenetic diversity showed a linear positive pattern along the gradient. Our results showed dragonfly assemblages were clustered along all the gradient, suggesting that environmental filtering sorted the assemblages. Whereas damselfly species assemblages were clustered at mid-latitude and overdispersed into both extremes of gradient, probably community assembly is driving by thermal gradients at mid-latitude, by competitive exclusion at south extreme, and by different origins of the biota at the boreal zone. Our results show that apparently most ancestral lineages of Odonata inhabit tropical zones, where diversified and dispersed to the temperate region, although likely also have been diversified into regions of NA, which might be linked with the highest species richness at mid-latitude for both suborders.
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.