During litter decomposition, part of the water-soluble components of the material dissolve (leach) rapidly into available water in the environment. Studies on litter decomposition that quantify mass-loss from litterbags integrate leaching and mineralization. In contrast to Lind et al. (2022), we believe that correcting for leaching in (terrestrial) litterbags studies such as the Tea Bag Index will result in more uncertainties than it resolves. This is mainly because leaching is a continuous process and because leached material can still be mineralized after leaching. Further, amount of material that potentially leaches from tea is comparable to other litter types. When correcting for leaching, it is key to be specific about the employed method, just like being specific about the study specific definition of decomposition.
Eastern wild turkeys (Meleagris gallopavo silvestris) exhibit social hierarchies wherein dominance is established through agnostic interactions within social groups. When dominant individuals effectively monopolize reproductive opportunities, asynchronous breeding can occur, which may disproportionately influence individual fitness within social groups. For females, higher ranked individuals may witness reproductive advantages associated with earlier nesting than subordinate conspecifics. We evaluated reproductive synchrony within and between presumed social groups of GPS-tagged female eastern wild turkeys by inferring female social rank based on timing of nest initiation. We examined 30 social groups with an average of 7 females per group (range 2 - 15) during 2014-2019 in west-central Louisiana. We found that the estimated number of days between first nest initiation across females within social groups varied between 3-7 days across years, and the number of days between nest attempts was lower for successful than failed attempts. Our findings suggest that social hierarchies may influence reproductive success in female wild turkeys, and we postulate that social constraints could cause variation in timing of nest initiation for females within social groups.
Very little is known about factors determining the assemblage structure of megadiverse polyphagous-herbivore scarab chafers in the tropics (Coleoptera: Scarabaeidae). Here, we examined the composition of Sri Lankan chafer assemblages and investigated whether it is influenced more by the general ecoclimatic situation, macrohabitat, of indetermined stochastic biotic and abiotic factors of each locality. We also explored the influence of the latter on separate lineages and general body size. Based on dedicated field surveys conducted during the dry and wet seasons, we examined 4847 chafer individuals of 105 species sampled using multiple UV-light traps in 11 localities covering different forest types and altitudinal zones. Assemblages were assessed for compositional similarity, species diversity, and abundance within four major eco-spatial partitions: forest types, elevational zones, localities, and macrohabitats. Our results revealed that assemblages were shaped mainly by locality stochastics, and to a minor extent by ecoclimatic conditions. Macrohabitat had little effect on the assemblage composition. This was true for the entire chafer assemblage as well as for all single lineages or different body size classes. However, in medium and large specimens the contrasts between localities were less pronounced, which was not the case for individual lineages of the assemblage. Contrasts of assemblage similarity between localities were much more evident than those for forest types and elevation zones. Significant correlation between species composition and geographic distance was found only for the assemblage of small-bodied specimens. Seasonal change (dry-wet) in species composition was minor and only measurable in a few localities.
Diospyros (Ebenaceae) is a widely distributed genus of trees and shrubs native to tropical and subtropical regions, with numerous species valued for their fruits (persimmons), timber, and medicinal values. However, information regarding their plastomes and chloroplast evolution is scarce. The present study performed comparative genomic and evolutionary analyses on plastomes of 18 accepted Diospyros species, including three newly sequenced ones. Our study showed a highly conserved genomic structure across the species, with plastome size ranging from 157,321 bp (D. jinzaoshi) to 157,934 bp (D. deyangensis). These plastomes encoded 134–138 genes, including 89–91 protein-coding genes, 1–2 pseudogenes (Ψycf1 for all, Ψrps19 for a few), 37 tRNA genes, and 8 rRNA genes. Comparative analysis of Diospyros identified the intergenic regions (trnH-psbA, rps16-trnQ, trnT-psbD, petA-psbJ, trnL-trnF-ndhJ) as the mutational hotspots in these species. Phylogenomic analyses identified three main groups within the genus designated as the evergreen, deciduous, and island groups. The codon usage analysis identified 30 codons with relative synonymous codon usage (RSCU) values greater than 1 and 29 codons ending with A and U bases. A total of three codons (UUA, GCU, and AGA) with highest (RSCU) values were identified as the optimal codons. ENC-plot indicated the significant role of mutational pressure in shaping codon usage, while most protein-coding genes in Diospyros experienced relaxed purifying selection (Ka/Ks < 1). Additionally, the ndhG, rpoC1, and ycf3 genes showed positive selection (Ka/Ks > 1) in the island, deciduous, and both deciduous and evergreen species, respectively. Thus, the results provide a foundation for elaborating Diospyros’s genetic architecture and taxonomy, conserving genetic diversity and enriching genetic resources.
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.
Phenotypic divergence is an important consequence of restricted gene flow in insular populations. This divergence can be challenging to detect when it occurs through subtle shifts in morphological traits, particularly in traits with complex geometries, like insect wing venation. Here, we employed geometric morphometrics to assess the extent of variation in wing venation patterns across reproductively isolated populations of the social sweat bee, Halictus tripartitus. We examined wing morphology of specimens sampled from a reproductively isolated population of H. tripartitus on Santa Cruz Island (Channel Islands, Southern California). Our analysis revealed significant differentiation in wing venation in this island population relative to conspecific mainland populations. We additionally found that this population-level variation was less pronounced than the species-level variation in wing venation among three sympatric congeners native to the region, Halictus tripartitus, Halictus ligatus, and Halictus farinosus. Together, these results provide evidence for subtle phenotypic divergence in an island bee population. More broadly, these results emphasize the utility and potential of wing morphometrics for large-scale assessment of insect population structure.
Siraitia grosvenorii, an economically important plant species with high medicinal value, is endemic to subtropical China. To determine the population structure and origin of cultivated S. grosvenorii, we examined the variation in three chloroplast DNA regions (trnR-atpA, trnH-psbA, trnL-trnF) and two nuclear gene orthologs (CHS and EDL2) of S. grosvenorii in 130 individuals, selected from 13 wild populations across its natural distribution range, and 21 cultivated accessions using a phylogeographic approach. The results showed non-overlapping distribution of chlorotypes, three distinct chloroplast genetic groups restricted to different mountain ranges, and comparable nuclear diversity among the distinct geographical groups, suggesting the existence of at least three separate refugia. The current phylogeographic patterns of S. grosvenorii probably resulted from long-term survival in multiple refugia and limited expansion. Our results also demonstrated that wild populations in northeastern Guangxi share the same gene pool as cultivated S. grosvenorii accessions, suggesting that the current cultivars originated from wild populations distributed in northeastern Guangxi. The results of this study provide insight into improving the efficiency of S. grosvenorii breeding using a genetic approach, and outline measures for the conservation of its genetic resources.
Ecuador has both high richness and high endemism of species which are increasingly threatened by anthropic pressures, including roads. However, research evaluating the effects of roads remains scarce, making it difficult to develop mitigation plans. Here we present the first national assessment of wildlife mortality that allow us to 1) identify species and areas where mortality occurs due to collision with vehicles and 2) reveal knowledge gaps. We bring together data from systematic surveys and citizen science efforts in Ecuador to present a dataset with >5000 wildlife roadkill records from 454 species. Systematic surveys were reported by ten studies conducted in five out of the 24 Ecuadorian provinces. Collectively they revealed 282 species with mortality rates ranging from 0.008 to 95.56 ind./km/year. The highest rates were for the yellow warbler Setophaga petechia in Galápagos (95.56 ind./km/year), the cane toad Rhinella marina in Napo (16.91 ind./km/year), and the small ground-finch Geospiza fuliginosa in Galápagos (14.11 ind./km/year). Citizen science and other no systematic monitoring provided 1705 roadkill records representing all the 24 provinces of Ecuador and 299 species. The common opossum Didelphis marsupialis, the Andean white-eared opossum Didelphis pernigra, and the yellow warbler Setophaga petechia were more commonly reported (250, 104, and 81 individuals respectively). Across all sources, we found 15 species listed as Threatened and six as Data Deficient by the IUCN. We suggest stronger research efforts on areas where mortality of endemic or threatened species could be critical for populations, such as in Galápagos. This first assessment of wildlife mortality on Ecuadorian roads represents contributions from several sectors including academia, members of the public, and government underlining the value of wider engagement and collaboration. We hope these findings and the compiled dataset will guide sustainable planning of infrastructure in Ecuador and ultimately, contribute to reduce wildlife mortality on roads.
Characterizing variation and association of plant traits is critical for understanding plant adaptation strategies and community-building mechanisms. However, little is known about the variation in leaf traits and the association between traits in desert plants of different life types. We used principal components analysis, Pearson’s correlation, phylogenetic independent contrasts, linear mixed model, and variance decomposition to explore the variation and association of ten leaf traits in 22 desert plants in the arid area. Our results showed that: (1) Interspecific variation in leaf traits contributed more to total variation than intraspecific variation. (2) Intraspecific and interspecific variation in leaf traits were different among different life forms, except for some traits that showed intraspecific variation higher than interspecific in some functional types, other traits with interspecific variation higher than intraspecific variation. (3) Desert plants have a one-dimensional leaf economic spectrum, in which shrubs are a fast acquisitive resource strategy, and herbs are a conservative resource strategy. (4) There were trade-offs between leaf traits, which were influenced by phylogeny. Our results suggest that variation of leaf traits mainly comes from interspecific variation, but intraspecific variation cannot be ignored. In addition, species with different life forms will adopt different ecological strategies to adapt to arid habitats. Therefore, we should study the variation and association of plant traits according to different functional types, in the future.
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. Describing and explaining patterns of individual animal behaviors in situ, and their repeatability over the annual cycle, is an emerging field in ecology owing largely to advances in tagging technology. 2. We describe individual movements of adult Sakhalin taimen Parahucho perryi, an endangered salmonid fish, in the headwaters of a river in northern Japan during the spring spawning season over two years. 3. Migration timing, separated into stages prior to, during, and following the spawning period, was found to be more consistent and repeatable for females than males. 4. We hypothesized that the observed coordinated movement within seasons, and repeatability in migration timing across seasons, could result from 1) individual-specific responsiveness resulting from endogenous, biological traits that are mediated by environmental factors, or 2) social interactions among comigrating individuals. 5. We found that water temperature and water level experienced by fish near the river mouth approximately a week before arrival at the spawning ground explained variability in run timing between years for females but not males. 6. We found no evidence of conspecific attraction or repulsion resulting from social interactions among the spawners and post-spawners. 7. We conclude that individual-specific responsiveness to environmental cues was the likely mechanism underpinning the observed migration timing and movement patterns. 8. Determining the importance of these environmental and social factors not only during spawning but also during non-breeding life-history stages would contribute to a more comprehensive understanding of migratory connectivity in this species.
Automated 3D-image based tracking systems are new and promising devices to investigate the foraging behaviour of flying animals with great accuracy and precision. 3D analyses can provide accurate assessments of flight performance in regard to speed, curvature, and hovering. However, there have been few applications of this technology in ecology, particularly for insects. We used this technology to analyse the behavioural interactions between the Western honey bee Apis melifera and its invasive predator the Asian hornet, Vespa velutina nigrithorax. We investigated whether predation success could be affected by flight speed, flight curvature, and hovering of the Asian hornet and honey bees in front of one beehive. We recorded a total of 603,259 flight trajectories and 5,175 predator-prey flight interactions leading to 126 successful predation events, representing 2.4% predation success. Flight speeds of hornets in front of hive entrances were much lower than that of their bee prey; in contrast to hovering capacity, while curvature range overlapped between the two species. There were large differences in speed, curvature and hovering between the exit and entrance flights of honey bees. Interestingly, we found hornet density affected flight performance of both honey bees and hornets. Higher hornet density led to a decrease in the speed of honey bees leaving the hive, and an increase in the speed of honey bees entering the hive, together with more curved flight trajectories. These effects suggest some predator avoidance behaviour by the bees. Higher honey bee flight curvature resulted in lower hornet predation success. Results showed an increase of predation success when hornet number increased up to 8 individuals, above which predation success decreased, likely due to competition among predators. Although based on a single colony, this study reveals interesting outcomes derived from the use of automated 3D tracking to derive accurate measures of individual behaviour and behavioural interactions among flying species.
The Masai giraffe has experienced a population decline from 70,000 to 35,000 in the past three decades and was declared an endangered subspecies by the IUCN in 2019. The remaining population is divided into smaller subpopulations dispersed west and east of the Gregory Rift Valley (GRV) in Tanzania, Kenya, and Zambia. The steep escarpments of the GRV are formidable barriers to migration and gene flow and the few remaining natural corridors are now occupied by human settlements. To assess the impact of the GRV on Masai giraffe gene flow, we examined nuclear and mitochondrial DNA variation in subpopulations east and west of the Manyara and Eyasi escarpments of the Rift in northern Tanzania. Strikingly, evidence from mtDNA variation, which measures female-mediated gene flow, suggests that females have not migrated across the GRV between major subpopulations in the Serengeti and Tarangire ecosystems since the approximate time that Masai giraffes emerged as a (sub)species 250kya. In contrast the analysis of nuclear DNA variation shows that male-mediated gene flow across the GVR has occurred over most of the history of Masai giraffes but may have ceased in the recent past as natural migratory routes across the escarpment have been blocked by human activities. These findings suggest that the Masai giraffe is now split into two separate metapopulations and in the absence of gene flow will eventually become separate species with populations of less than 20,000.
The National Forestry Commission of Mexico continuously monitors forest structure within the country’s continental territory by the implementation of the National Forest and Soils Inventory (INFyS). Due to the challenges involved in collecting data exclusively from field surveys, there are spatial information gaps for important forest attributes. This can produce bias or increase uncertainty when generating estimates required to support forest management decisions. Our objective is to predict the spatial distribution of tree height and tree density in all Mexican forests. We performed wall-to-wall spatial predictions of both attributes in 1-km grids, using ensemble machine learning across each forest type in Mexico. Predictor variables include remote sensing imagery and other geospatial data (e.g., vegetation indexes, surface temperature). Training data is from the 2009-2014 cycle (n>26,000 sampling plots). Spatial cross validation suggested that the model had a better performance when predicting tree height r2=0.4 [0.15,0.55] (mean[min, max]) than for tree density r2=0.2[0.10,0.31]. Maximum values of tree height were for coniferous forests, coniferous-broadleaf forests and cloud mountain forest (~36 m, 30 m and 21 m, respectively). Tropical forests had maximum values of tree density (~1370 trees/ha), followed by tropical dry forest (1006 trees/ha) and coniferous forest (988 trees/ha). Although most forests had relatively low values of uncertainty, e.g., values <40%, arid and semiarid ecosystems had high uncertainty in both tree height and tree density predictions, e.g., values >60%. The applied open science approach we present is easily replicable and scalable, thus it is helpful to assist in the decision-making and future of the National Forest and Soils Inventory. This work highlights the need for technical capabilities aimed to use and resignify all the effort done by the Mexican Forestry Commission in implementing the INFyS.
1. Understanding animals’ selection of microhabitats is important in both ecology and biodiversity conservation. However, there is no generally accepted methodology for the characterisation of microhabitats, especially for vegetation structure. 2. Here we present a method that objectively characterises vegetation structure by using automated processing of images taken of the vegetation against a whiteboard under standardised conditions. We developed an R script for automatic calculation of four vegetation structure variables derived from raster data stored in the images: leaf area (LA), height of closed vegetation (HCV), maximum height of vegetation (MHC), and foliage height diversity (FHD). 3. We demonstrate the applicability of this method by testing the influence of vegetation structure on the occurrence of three viperid snakes in three grassland ecosystems: Vipera graeca in mountain meadows in Albania, V. renardi in loess steppes in Ukraine and V. ursinii in sand grasslands in Hungary. 4. We found that the variables followed normal distribution and there was minimal correlation between those. Generalized linear mixed models revealed that snake occurrence was positively related to HCV in V. graeca, to LA in V. renardi and to LA and MHC in V. ursinii, and negatively to FHD in V. renardi, and to HCV in V. ursinii. 5. Our results demonstrate that biologically meaningful vegetation structure variables can be derived from automated image processing. Our method minimises the risk of subjectivity in measuring vegetation structure, allows upscaling if neighbouring pixels are combined, and is suitable for comparison of or extrapolation across different grasslands, vegetation types or ecosystems.
Resource fluctuation is a major driver of animal movement, influencing strategic choices such as residency vs nomadism, or social dynamics. The Arctic tundra is characterized by strong seasonality: resources are abundant during the short summers but scarce in winters. Therefore, expansion of boreal-forest species onto the tundra raises questions on how they cope with winter-resource scarcity. We examined a recent incursion by red foxes (Vulpes vulpes) onto the coastal tundra of western Hudson Bay, an area historically occupied by Arctic foxes (Vulpes lagopus) that lacks access to anthropogenic foods, and compared seasonal shifts in space use of the two species. We used 4 years of telemetry data following 8 red foxes and 11 Arctic foxes to test the hypothesis that the movement strategies of both species are primarily driven by temporal variability of resources. We also predicted that the harsh tundra conditions in winter affect red foxes more than Arctic foxes, which are adapted to this environment. Dispersal was the most frequent winter movement strategy in both fox species, despite its association with high mortality (winter mortality was 9.4 times higher in dispersers than residents). Red foxes consistently dispersed towards the boreal forest, whereas Arctic foxes primarily used sea ice to disperse. Home range size of red and Arctic foxes did not differ in summer, but resident red foxes substantially increased their home range size in winter, whereas home range size of resident Arctic foxes did not change seasonally. As climate changes, abiotic constraints on some species may relax, but associated declines in prey communities may lead to local extirpation of many predators, notably by favoring dispersal during resource scarcity.
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.
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.