Species distribution patterns are essential for the conservation of biodiversity. The aim of this study was to evaluate the influence of multiple ecological hypotheses on the spatial patterns of rodent species richness in China. First, we divided the geographic region of China into 80 × 80 km2 grid cells and mapped the distribution ranges of the 237 rodent species. Rodent taxa were separated into three response variables based on their distribution: (a) all species, (b) non-endemic species, and (c) endemic species. The predictors were divided into four factor sets: (a) energy-water, (b) climatic seasonality, (c) habitat heterogeneity, and (d) human factors, which were used to represent four different ecological hypotheses. We then performed multiple regression analysis (OLS), spatial autoregressive models (SAR), and variation partitioning analyses to determine the effects of predictors on the spatial patterns of rodent species. The Hengduan Mountains and surrounding mountains in southwest China showed the highest species richness and endemism. Habitat heterogeneity is the most important factor explaining the species richness distribution patterns across all species and non-endemic species. Endemic species richness patterns are most susceptible to seasonal changes in climate and least affected by human factors. The effects of energy and water on the three response variables showed consistent levels of importance.
The eastern tree hyrax is thought to be a solitarily living arboreal species of the forests of East Africa. However, in the coast of Kenya, indigenous forests have been almost entirely cleared, and some of the last tree hyrax populations live in limestone rocky formations and caves. Interestingly, they seem to be living in social groups. Here, we describe and document photographically these unique tree hyrax populations. We also describe their acoustical communication and their calling activity in three different habitats. Based on these animals' physical appearance and acoustic analyses of their calls, they represent the species eastern tree hyrax, Dendrohyrax validus. Due to immence pressure from humans, the future of these small and isolated, cave-living tree hyrax populations does not seem bright.
1. Our understanding of how bees (Apoidea) use temperate forests is largely limited to sampling the understory and forest floor. Studies over the last decade have demonstrated that bee communities are vertically stratified within forests, yet the ecology of bee assemblages immediately above the canopy, the canopy-aerosphere interface, remains unexplored. 2. We sampled and compared bee communities above the canopy of a temperate forest to the understory (1 m), midstory (10 m), and canopy (20 m) on the campus of the University of Massachusetts, in Amherst, Massachusetts, USA from April – August, 2021. 3. Overall, we found that assemblages above the canopy had more bees than in the understory, were distinct in composition from all other strata, and included the greatest proportion of unique species. Bee abundance and species richness were highest in the understory throughout the spring (April and May) and decreased as the season progressed, while bee abundance and species richness at higher strata increased into the summer months. We also found that bees with preferences to nest in moist and rotting wood were largely restricted to canopy and midstory strata. 4. We conclude that bee assemblages occupying the space above the forest canopy are abundant and diverse, and their unique composition suggests that this canopy-aerosphere interface plays an additional role in the bee community of temperate forests. Alternatively, our findings question how forest bee communities should be defined while highlighting the need for research on fundamental processes governing species stratification in and above the canopy.
1. Animal abundance estimation is increasingly based on drone or aerial survey photography. Manual post-processing has been used extensively, however volumes of such data are increasing, necessitating some level of automation, either for complete counting, or as a labour-saving tool. Any automated processing can be challenging when using the tools on species that nest in close formation such as Pygoscelid penguins. 2. We present here an adaptation of state-of-the-art crowd-counting methodologies for counting of penguins from aerial photography. 3. The crowd-counting model performed significantly better in terms of model performance and computational efficiency than standard Faster RCNN deep-learning approaches and gave an error rate of only 0.8 percent. 4. Crowd-counting techniques as demonstrated here have the ability to vastly improve our ability to count animals in tight aggregations, which will demonstrably improve monitoring efforts from aerial imagery.
Understanding the drivers of morphological convergence requires investigation into its relationship with behavior and niche-space, and such investigations in turn provide insights into evolutionary dynamics, functional morphology, and life history. Mygalomorph spiders (trapdoor spiders and their kin) have long been associated with high levels of homoplasy, and many convergent features can be intuitively associated with different behavioral niches. Using genus-level phylogenies based on recent genomic studies and a newly assembled matrix of discrete behavioral and somatic morphological characters, we reconstruct the evolution of burrowing behavior in the Mygalomorphae, compare the influence of behavior and evolutionary history on somatic morphology, and test hypotheses of correlated evolution between specific morphological features and behavior. Our results reveal the simplicity of the mygalomorph adaptive landscape, with opportunistic, web-building taxa at one end, and burrowing/nesting taxa with structurally-modified burrow entrances (e.g., a trapdoor) at the other. Shifts in behavioral niche, in both directions, are common across the evolutionary history of the Mygalomorphae, and several major clades include taxa inhabiting both behavioral extremes. Somatic morphology is heavily influenced by behavior, with taxa inhabiting the same behavioral niche often more similar morphologically than more closely-related but behaviorally-divergent taxa, and we were able to identify a suite of 11 somatic features that show significant correlation with particular behaviors. We discuss these findings in light of the function of particular morphological features, niche dynamics within the Mygalomorphae, and constraints on the mygalomorph adaptive landscape relative to other spiders.
Abstract: Throughout evolutionary history, animals are finely tuned to adjust their behaviors corresponding to environmental variations. Behavioral flexibility represents an important component of a species’ adaptive capacity in the face of rapid anthropogenetic environmental change, and knowledge of animal behaviours is increasingly recognized in conservation biology. In aquatic ecosystem, variation of water depth is a key factor affecting the availability of food, thus the foraging behaviours of many waterbirds, especially piscivores. In this study, we compared the foraging behaviours of Scaly-sided Merganser (Mergus squamatus), an endangered migratory diving duck endemic to east Asia, in habitats with different water depth, using video camera records obtained from the known wintering sites during three winters from 2018-2020. Further, the energy expenditure of foraging behavior profile and energy intake based on fish sizes were calculated to study the foraging energetics. In total, 200 effective video footages that contained 1,086 minutes with 17,995 behaviours and 163 events of catching fish were recorded. Results showed that 1) time length for fishing (including eye-submerging, head-dipping, diving and food handling) of Mergus squamatus in shallow waters was significantly more than in deep waters; 2) Mergus squamatus spent significantly more time for preparing (including vigilance, preening and swimming) in deep waters than in shallow waters; 3) the mean catch rate was 0.28 fish/minute in shallow waters, which is significantly higher than the value of 0.13 fish/minute in deep waters; 4) despite the distinct foraging behaviour profiles and energy intakes, Mergus squamatus showed similar energetics in shallow and deep waters. We concluded that Mergus squamatus is a good example of behavioural flexibility that aligns with expectations of optimum foraging theory, in that it behaves in accordance to resource availability in different environments, resulting in high foraging efficiency. The behavioural flexibility can be related to its evolution history.
DNA barcoding has been used worldwide to identify biological specimens and to delimit species. It represents a cost-effective, fast and efficient way to assess biodiversity with help of the public Barcode of Life Database (BOLD) accounting for more than 236,000 animal species and more than ten million barcode sequences. Here, we performed a meta-analysis of available barcode data of central European Coleoptera to detect intraspecific genetic patterns among ecological groups in relation to geographic distance with the aim to investigate a possible link between infraspecific variation and species ecology. We collected information regarding feeding style, body size as well as habitat and biotope preferences. Mantel tests and two variants of Procrustes analysis, both involving the Principal Coordinates Neighborhood Matrices (PCNM) approach, were applied on genetic and geographic distance matrices. However, significance levels were too low to further use the outcome for further trait investigation: these were in mean for all ecological guilds only 7.5, 9.4, or 15.6 % for PCNM+PCA, NMDS+PCA, and Mantel test, respectively, or at best 28% for a single guild. Our study confirmed that certain ecological traits were associated with higher species diversity and foster stronger genetic differentiation. Results suggest that increased numbers of species, sampling localities, and specimens for a chosen area of interest may give new insights to explore barcode data and species ecology for the scope of conservation on a larger scale.
Flower-visiting insects have co-evolved with flowering plants. While it has been shown that floral traits and environmental factors influence insect visitation during the day, it is still unclear how these factors influence their visitation at night. We sampled a montane meadow located near Jilin in northeastern China in July and August of 2019, for 4 nights each month, and two time periods each night. We sampled 94 flower-visiting insect species in total and documented floral traits and ambient factors. We first allocated all the insects to three functional groups (pollination, predation, and herbivory). Most nocturnal insects exhibited predation behavior, and had the highest species turnover rate. We then focused on environmental factors and found that ambient temperature and relative humidity strongly influenced the diversity of flower-visiting insects. In addition, variation partitioning analysis suggested that ambient temperature had a stronger effect on the flower-visiting insects during the early night hours, whereas relative humidity had a stronger effect on them in the later night hours. Finally, focusing on floral traits, most insects preferred flowers with moderately sized corolla diameters (20 to 30 mm). Furthermore, display size had a strong linear correlation with flower-visiting insect species richness and frequency of presence. In sum, our findings suggest that ambient temperature, relative humidity and floral display size strongly regulate the behavior of nocturnal flower-visiting insects.
Many populations of long-distance migrant shorebirds are declining rapidly. Since the 1970s, the Lesser Yellowlegs (Tringa flavipes) has experienced a pronounced reduction in abundance of ~63%. The potential causes of the species’ decline are complex and interrelated yet understanding the timing of migration and seasonal routes used by this species will aid in directing conservation planning to address potential threats. During 2018–2021, we tracked 118 adult Lesser Yellowlegs using GPS satellite tags deployed on birds from five breeding and two migratory stopover locations spanning the boreal forest of North America from Alaska to eastern Canada. Our objectives were to quantify migratory connectivity and identify key stopover and non-breeding locations. Individuals tagged in Alaska and central Canada followed similar southbound migratory routes through the Prairie Pothole Region of North America, whereas birds tagged in eastern Canada completed multi-day transoceanic flights covering distances of >4,000 km across the Atlantic between North and South America. Upon reaching their non-breeding locations, Lesser Yellowlegs populations overlapped, resulting in weak migratory connectivity. Lastly, freshwater and agricultural habitats of the Prairie Pothole region supported the highest proportion of Lesser Yellowlegs during southbound migration. Our findings suggest that while Lesser Yellowlegs travel long distances and traverse numerous political boundaries each year, the breeding population from which an individual originates likely has the greatest influence on which threats birds experience during migration. Further, the species’ dependence on wetlands in agricultural landscapes during migration may make them vulnerable to threats related to agricultural practices, such as pesticide exposure.
Birds of prey frequently feature in reintroductions and the hacking technique is typically used. Hacking involves removing large nestlings from donor populations, transferring them to captivity, feeding them ad libitum. Potentially, via the hacking method, stress of captivity and disruption of parental feeding may be detrimental. Alternatively, provision of ad libitum food may be advantageous. Although hacking has underpinned reintroduction project successes there has been no research on how the method may affect the health and nutritional status of translocated birds during captivity. We compared blood chemistry data from 55 young White-tailed Eagles, translocated from Norway as part of the species’ reintroduction to Scotland, from sampling soon after arriving in captivity and again (≈ 42 d later) before their release. Numerous significant differences between first and second samples were found, but no significant interactions showed that sexes responded similarly to captivity. According to hematological and biochemical metrics, individuals showed several changes during captivity, including in red blood cell parameters, plasma proteins and white cellular parameters related to the immune system, that indicated improved health status. Captivity with ad libitum food was associated with decreased urea and uric acid values: high values can indicate nutritional stress. Urea values became more normally distributed before release, indicating that ad libitum food had reduced nutritional differences between early nestlings in the season and later ones. Despite plentiful food, both sexes lost body mass before release, suggesting an inherent physiological mechanism to improve flight performance in fledglings. We conclude that hacking improved the health and nutritional status of released eagles which is likely to enable birds to cope with greater costs of exploratory behavior which they may require in reintroduction projects. In this context, we note the absence of survival differences between hacked and wild raptors in previous research.
Camera traps have recently become in-situ sensors for collecting information on animal abundance and occupancy estimates. When deployed over a large landscape, camera traps have become ideal for measuring the health of ecosystems, particularly in unstable habitats where it can be dangerous or even impossible to observe with conventional methods. However, manual processing of imagery is extremely time and labor intensive. Due to this, many studies have started to employ the use of machine learning tools, such as convolutional neural networks (CNNs), with the presumption that a large number of images (millions) is needed to devise an effective identification or classification model. We examined specific factors pertinent to camera trap placement in the field that may influence the accuracy metrics of a deep learning model that has been trained with a small set of images. False negatives and false positives may occur due to a variety of reasons that make it hard even for a human observer to classify, including local weather patterns and degree of light present. We trained a CNN to detect 16 different object classes (14 animal species, humans, and fires) across 9,576 images taken from camera traps placed in the Chernobyl Exclusion Zone. After analyzing wind speed, cloud cover, and temperature, there was a significant relationship with CNN error and temperature. Furthermore, we found that the model was more successful when images were taken during the day as well as when precipitation is not present. Given the relationship between the influencing variables studied and model error rates, it will be important to obtain a wider breadth of events in differing weather and daytime factors for future classification models. This study suggests further exploration into the causes of error in classification modeling is necessary given the unique challenges posed by the analysis of camera trap imagery.
An individual’s size in early stages of life may be an important source of individual variation in lifetime reproductive performance, as size effects on ontogenetic development can have cascading physiological and behavioral consequences throughout life. Here, we explored how natal size influences subsequent reproductive performance in grey seals (Halichoerus grypus) using repeated encounter and reproductive data on a marked sample of 363 females that were measured for length at ~4 weeks of age and eventually recruited to the Sable Island breeding colony. Two reproductive traits were considered: provisioning performance (mass of weaned offspring), modeled using linear mixed effects models; and reproductive frequency (rate at which a female returns to breed), modeled using mixed-effects multistate mark-recapture models. Mothers with the longest natal lengths produced pups 8 kg heavier and were 20% more likely to breed in a given year than mothers with the shortest lengths. Correlation in body lengths between natal and adult life stages, however, is weak: longer pups do not grow to be longer than average adults. Thus covariation between natal length and future reproductive performance appears to be a carry-over effect, where the size advantages afforded in early juvenile stages may allow enhanced long-term performance in adulthood.
Host-gut microbiota interactions are complex and can have a profound impact on the ecology and evolution of both counterparts. Several host traits such as systematics, diet and social behavior, and external factors such as prey availability and local environment are known to influence the composition and diversity of the gut microbiota. In this study, we investigate the influence of systematics, sex, host size, and locality/habitat on gut microbiota diversity in five lizard species from two different sites in Portugal: Podarcis bocagei and Podarcis lusitanicus, living in syntopy in a rural area in northern Portugal (Moledo); the invasive Podarcis siculus and the native Podarcis virescens, living in sympatry in urbanized environment (Lisbon); and the invasive Teira dugesii also living in an urban area (Lisbon). We also infer the potential microbial transmission occurring between species living in sympatry and syntopy. To accomplish these goals, we use a metabarcoding approach to characterize the bacterial communities from the cloaca of lizards, sequencing the V4 region of the 16S rRNA. Habitat/locality was an important factor explaining differences in gut bacterial composition and structure, with species from urbanized environments having higher bacterial diversity. Host systematics (i.e. species) influenced gut bacterial community structure only in lizards from the urbanized environment. We also detected a significant positive correlation between lizard size and gut bacterial alpha-diversity in the invasive species P. siculus, which could be due to its higher exploratory behavior. Moreover, estimates of bacterial transmission indicate that P. siculus may have acquired a high proportion of local microbiota after its introduction. These findings confirm that a diverse array of host and environmental factors can influence lizards gut microbiota.
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.
1. Given the sharp increase in agricultural and infrastructure development and the paucity of widespread data available for making conservation management decisions, a more rapid and accurate tool for identifying fish fauna in the world’s largest freshwater ecosystem, the Amazon, is needed. 2. Current strategies for identification of freshwater fishes require high levels of training and taxonomic expertise for morphological identification or genetic testing for species recognition at a molecular level. 3. To overcome these challenges, we built an image masking model (U-Net) and a convolutional neural net (CNN) to classify Amazonian fish in photographs. Fish used as training data were collected and photographed in tributaries in seasonally flooded forests of the upper Morona River valley in Loreto, Peru in 2018 and 2019. 4. Species identifications in the training images (n = 3,068) were verified by expert ichthyologists. These images were supplemented with photographs taken of additional Amazonian fish specimens housed in the ichthyological collection of the Smithsonian’s National Museum of Natural History. 5. We generated a CNN model that identified 33 genera of fishes with a mean accuracy of 97.9%. Wider availability of accurate freshwater fish image recognition tools, such as the one described here, will enable fishermen, local communities and community scientists to more effectively participate in collecting and sharing data from their territories to inform policy and management decisions that impact them directly.
Habitat divergence among close relatives is a common theme in ecology. While recent studies have frequently found that the abundance and diversity of plant species are regulated by soil microbes, little is known whether soil microbes can also affect the habitat distributions of plants. To fill in this knowledge gap, we investigated whether interactions with soil microbes restrict habitat distributions of closely related oaks (Quercus spp.) in eastern North America. We performed a soil inoculum experiment using two pairs of sister species that show habitat divergence: Quercus alba (local species) vs. Q. michauxii (foreign), and Q. shumardii (local) vs. Q. acerifolia (foreign). To test whether host-specific soil microbes are responsible for habitat restriction, we investigated the impact of local sister live soil (containing soil microbes associated with local sister species) on the survival and growth of local and foreign species. Secondly, to test whether habitat-specific soil microbes are responsible for habitat restriction, we also examined the effect of local habitat live soil (containing soil microbes within local sister’s habitats, but not directly associated with roots of local sister species) on the seedlings of local and foreign species. We found that local sister live soil decreased the survival and biomass of foreign species’ seedlings while increased those of local species, which supports the roles of host-specific microbes in mediating habitat exclusion. In contrast, local habitat live soil did not differentially affect the survival or biomass of the local vs. foreign sister species, providing no support for the roles of habitat-specific microbes. Our study indicates that soil microbes associated with one sister species can suppress the recruitment of the other host species, contributing to habitat partitioning of the closely related oaks. Our findings emphasize that considering the complex interactions with soil microbes is essential for understanding habitat distributions of closely related plants.
Thousands of plant species produce both extrafloral nectaries (EFNs) on their leaves and nutrient-rich appendages on their diaspores (elaiosomes). Although their individual ecology is well-known, any possible functional link between them has been ignored. Here, we recognized their co-presence in the shrub, Adenanthos cygnorum (Proteaceae), and studied their function and interaction. We observed that ants frequently visit both structures, seeds are attractive to vertebrate granivores but are released into a leafy cup from where they are harvested by ants and taken to their nests, from which seeds, lacking elaiosomes, germinate after fire. We showed that juvenile plants do not produce EFNs and are not visited by ants. We conclude that EFNs are not just an indirect adaptation to minimize herbivory via aggressive ants (or parasitoid wasps) but specifically enhance reproductive success by inducing ants to visit the plant throughout the year, promoting discovery of the seasonally available, elaiosome-bearing seeds on the plant and transporting them to their nests, so avoiding the risk of granivory should seeds fall to the ground.
The buffy-tufted-ear marmoset (Callithrix aurita) is a small primate endemic to the Brazilian Atlantic Forest biome, and one of the 25 most endangered primates in the world, due to fragmentation, loss of habitat, and invasion by allochthonous Callithrix species. Using occurrence data for C. aurita from published data papers, we employed model selection and cumulative AICc weight (w+) to evaluate whether fragment size, distance to fragments with allochthonous species, altitude, connectivity, and surrounding matrices influence the occurrence of C. aurita within its distributional range. Distance to fragments with C. jacchus (w+ = 0.94) and non-vegetated areas (w+ = 0.59) correlated negatively with C. aurita occurrence. Conversely, the percentage of agriculture and pasture mosaic (w+ = 0.61) and the percentage of savanna formation (w+ = 0.59) in the surrounding matrix correlated positively with C. aurita occurrence. The findings indicate that C. aurita is isolated in forest fragments surrounded by potentially inhospitable matrices, along with the proximity of a more generalist and invasive species, thereby increasing the possibility of introgressive hybridization. The findings also highlighted the importance of landscape factors and allochthonous congeneric species for C. aurita conservation, besides indicating urgency for allochthonous species management. Finally, the approach used here can be applied to improve conservation studies of other endangered species, such as C. flaviceps, which is also endemic to the Brazilian Atlantic Forest and faces the same challenges.