The Gempylidae (snake mackerels) family, belonging to the order Perciformes, consists of about 24 species described in 16 genera primarily distributed in tropical, subtropical, and temperate areas worldwide. Despite substantial research on this family utilizing morphological and molecular approaches, taxonomy categorization in this group has remained puzzling for decades prompting the need for further investigation into the underlying evolutionary history among the gempylids using molecular tools. In this study, we characterized and compared eight complete mitochondrial genomes for five Gempylidae species [Neoepinnula minetomai, Neoepinnula orientalis, Rexea antefurcata, Rexea prometheoides, and Thyrsites atun] using Ion-Torrent sequencing. Using Bayesian Inference and Maximum-Likelihood tree search methods, we investigated the evolutionary relationships of seventeen Gempylidae species using mitogenome data. In addition, we estimate divergence times for extant gempylids. We identified two major clades that formed approximately 48.05 (35.89 – 52.04 mya) million years ago; Gempylidae 1 [Lepidocybium flavobrunneum, Ruvettus pretiosus, Neoepinnula minetomai, Neoepinnula orientalis, and Epinnula magistralis], and Gempylidae 2 [Thyrsites atun, Promethichthys prometheus, Nealotus tripes, Diplospinus multistriatus, Paradiplospinus antarcticus, Rexea antefurcata, Rexea nakamurai, Rexea prometheoides, Rexea solandri, Thyrsitoides marleyi, Gempylus serpens, and Nesiarchus nasutus]. The present study demonstrates the superior performance of complete mitogenome data compared to individual genes in phylogenetic reconstruction. In addition to Cytochrome c oxidase subunit 1, NADH dehydrogenase subunit 2, and Cytochrome b, which are frequently employed in phylogenetic investigations, NADH dehydrogenase subunit 5 provided adequate resolving power. Analyses of selection pressure revealed purifying selection is predominant in Gempylidae mitogenomes. By including T. atun individuals from different regions we demonstrate the potential for the application of mitogenomes in species phylogeography.
Aim The Neotropics, particularly South America, holds unparalleled high levels of species richness, when compared to other major biomes. Some neotropical areas are hotspots of a fragmentary known diversity of insects and are under manifest danger of biodiversity loss and climate change. Therefore, prompt estimates methods of its diversity are urgently required to complement slower traditional taxonomic approaches. Despite a variety of algorithms for delimiting species through single-locus DNA barcodes having been developed and applied for rapid estimates of species diversity in a wide array of taxa; however, tree-based and distance-based methods may lead to different group assignments, either overestimating or underestimating the number of putative species. Here, we investigate the performance of different DNA-based species delimitation approaches for a rapid biodiversity estimate of the diversity of Polypedilum (Chironomidae, Diptera) in South America. Location Worldwide Methods We analyze a mtDNA dataset comprising 1,492 specimens from 598 locations worldwide. Molecular operational taxonomic units (MOTUs) ranged from 267 to 520, based on the Barcode Index Number (BIN), Bayesian Poisson tree processes (bPTP), multi-rate Poisson tree processes (mPTP), single-rate Poisson tree processes (sPTP), and generalized mixed Yule coalescent (sGMYC) approaches. Results Our results highlight Polypedilum as a species-rich genus, yet incompletely documented, and found the sGMYC method to be the most adequate to estimate putative species in our dataset. Furthermore, based on these data, we describe the distribution of diversity and some biogeographical patterns of Polypedilum. Main Conclusions Findings imply the genus exhibited high levels of endemism and richness of species in the Neotropics, which confirmed our hypothesis that there are substantial differences in community structure between the Polypedilum fauna in South America and the neighboring regions.
Phoretic mites have been found attached to different body parts of red palm weevil (RPW), Rhynchophorus ferrugineus (Olivier, 1790), to disperse. However, the question of how the patterns of attachment sites are formed remains intriguing. Here, we conducted the first study of RPW-associated phoretic mites in Portugal, particularly in the districts of Viana do Castelo, Braga, Porto and Aveiro in Northern Portugal (macrohabitat), and investigated the patterns of mite distribution on six body parts of RPW (microhabitat). At the macrohabitat level, we detected seven phoretic mite taxa actively using RPW host in each of the four studied districts, all documented for the first time in association with this invasive exotic species in Portugal. However, their relative abundance (species evenness) varied between districts, as did species diversity. All examined weevils carried mites, and the prevalence of the different taxa did not differ between districts or sex of weevils. Measured by mean abundance and degree of aggregation, Centrouropoda sp. proved to be the common dominant taxon, while Acarus sp. and C. rhynchoporus were considered common subordinate taxa and Uroovobella sp., Mesostigmata, N. extremica and Dendrolaelaps sp. sparse taxa. At the microhabitat level, all taxa were present in all body parts of the RPW; the highest abundance was in a region encompassing the inner surface of the elytra and the membranous hind wings (subelytral space). Analysis of niche overlap revealed that the distribution patterns of phoretic mite taxa on the RPW were not randomly structured. In the subelytral space, interspecific coexistence of mites increased as a function of body size difference with the dominant Centrouropoda sp. We conclude that the distribution patterns of RPW-associated phoretic mites show body size-dependent effects that resulted in the dominant taxon displacing similar size taxa and accepting taxa with which it has the greatest size difference as co-habitants.
(Sceloporus undulatus) is a female-larger, sexually-size dimorphic lizard species that is heavily parasitized by chigger mites (Eutrombicula alfreddugesi). In particular, the intensity of mite parasitism is higher in male than in female juveniles during the period of time when sex differences in growth rate lead to the development of sexual size dimorphism (SSD). Sex-biased differences in fitness costs of parasitism have been documented in other species. We tested whether a sex-biased growth cost of parasitism contributes to the development of SSD in S. undulatus. We measured growth and mite loads in two cohorts of unmanipulated, field-active yearlings by conducting descriptive mark-recapture studies during the activity seasons of 2016 and 2019. Yearling males had consistently higher mid-summer mite loads and consistently lower growth rates than females. However, we found that growth rate and body condition were independent of mite load in both sexes. Furthermore, growth rates and mite loads were higher in 2019 than in 2016. Our findings suggest that juveniles of S. undulatus are highly tolerant of chigger mites and that any costs imposed by mites must be at the expense of functions other than growth. We conclude that sex-biased mite ectoparasitism does not contribute to sex differences in growth rate and the development of SSD.
The climate drives species distribution and genetic diversity; the latter defines the adaptability of populations and species. The ongoing climate crisis induces tree decline in many regions, compromising the mitigation potential of forests. Scientific-based strategies for prioritising forest tree populations are critical to managing the impact of climate change. Identifying future climate refugia, which are locations naturally buffering the negative impact of climate change, may facilitate local conservation. In this work, we conducted the populations’ prioritisation for Castanea sativa (sweet chestnut), a Neogene relict growing in the Caucasus global biodiversity hotspot. We generated genetic and ecological metrics for 21 sites in Georgia and Azerbaijan, which cover the natural range of sweet chestnut across the region. We demonstrated that climate primarily drives the pattern of genetic diversity in C. sativa, proved with a significant Isolation-by-Environment model. In future, climate change may significantly reorganise the species genetic diversity, inducing even some genetic loss, especially in the very distinct eastern fringe of the species range in Azerbaijan. Based on our combined approach, we mapped populations suitable for ex-situ and in-situ conservation, accounting for genetic variability and the location of future climate refugia.
Workers in the ant genus Pheidole show an extreme degree of morphological differentiation, with at least two distinct subcastes: minor workers are smaller and perform most of the colony tasks, whereas majors are larger, display disproportionately massive heads, and specialize in roles as defense and food processing. There is considerable interspecific variation in head shape within worker subcastes of Pheidole, which could affect how the stresses generated by the mandibular closing muscle contraction (0md1) spread throughout the head and influence bite force. To assess the role of head shape in stress patterns of Pheidole workers, we solve a set of Finite Element Analysis (FEA) while exploring variation in Pheidole worker head morphospace. We hypothesize that majors possess head shapes optimized for the generation of stronger bites. In addition, we expect that head shapes corresponding to the edges of morphological space in the genus would show mechanical limitations that could prevent further expanding the occupied morphospace. We vectorized Pheidole head shapes based on images of worker heads, considering species that represent mean shapes and the edges of the two main axes of each morphospace, for a total of five head shapes for each worker subcaste. We performed linear static FEA simulating the contraction of 0md1. Our results demonstrate that head shapes of majors are optimized to generate stronger bites given that stress generated on those shapes is distinctly directed towards the mandibles. Head shapes of minors tended to concentrate stresses around the mandibular articulations, with substantially lower and more diffuse stresses spreading throughout the head, indicating that such shapes are associated with weaker bites. Our results agree with the expectations regarding the main colony tasks performed by each worker subcaste, and we find some evidence of biomechanical limitations on extreme head shapes for majors and minors.
1. The structure, composition, and shape of teeth have been related to dietary specialization in many vertebrate species, except snakes. Yet, snakes have diverse dietary habits that may impact the shape of their teeth. We hypothesize that prey properties, such as hardness and shape, as well as feeding behavior, such as aquatic or arboreal predation, or holding vigorous prey, impose constraints on the evolution of tooth shape in snakes. 2. We compared the morphology of the dentary teeth of 63 species that cover the phylogenetic and dietary diversity of snakes, using 3D geometric morphometrics and linear measurements. 3. Our results show that prey hardness, foraging substrate and the main mechanical challenge are important drivers of tooth shape, size, and curvature. 4. Overall, long, slender, curved teeth with a thin layer of hard tissue are observed in species that need to maintain a grip on their prey. Short, stout, less curved teeth are associated with species that undergo high or repeated loads. 5. Our study demonstrates the diversity of tooth morphology in snakes and the need to investigate its underlying functional implications to better understand the evolution of teeth in vertebrates.
1. High latitude ecosystems are experiencing the most rapid warming on earth, expected to trigger a diverse array of ecological responses. Climate warming affects the ecophysiology of fish, and fish close to the cold end of their thermal distribution are expected to increase somatic growth from increased temperatures and a prolonged growth season, which in turn affects maturation schedules, reproduction and survival, boosting population growth. Accordingly, fish species living in ecosystems close to their northern range edge should increase in numerical importance and possibly displace cold-water adapted species. 2. We aim to document if and how population level effects of warming mediated by individual level responses to increased temperatures, shift community structure and composition in high latitude ecosystems. 3. We studied 11 cool-water adapted freshwater fish populations in communities dominated by cold-water adapted species to investigate changes in the relative importance of cool-water fish during the last 30 years of rapid warming in high latitude lakes. In addition, we studied the individual level responses to warming to clarify the potential mechanisms underlying the population effects. 4. Our long-term series‘ (1991-2020) reveal a marked increase in numerical importance of the cool-water fish species, perch, in ten out of eleven populations, and in most fish communities the cool-water species is now dominant. Moreover, we show that climate warming affects population level processes via direct and indirect temperature effects on the individuals. Specifically, the increase in abundance arises from increased survival of 0+ individuals, faster juvenile growth and ensuing earlier maturation, all boosted by climate warming. 5. The speed and magnitude of the response to warming in these high latitude fish communities strongly suggest that cold-water fish will be displaced by fish adapted to warmer water. Consequently, management should focus on climate adaptation limiting future introductions and invasions of cool-water fish and mitigating harvesting pressure on cold-water fish.
Passive acoustic monitoring (PAM) is a cost-effective method for monitoring cetacean populations compared to techniques such as aerial and ship-based surveys. The C-POD (Cetacean POrpoise Detector) has become an integral tool in monitoring programmes globally for over a decade, providing standardised metrics of occurrence that can be compared across time and space. However, the phasing out of C-PODs following development of the new F-POD (Full waveform capture Pod) with increased sensitivity, improved train detection, and reduced false positive rates, represents an important methodological change in data collection, particularly when being introduced into existing monitoring programmes. Here, we compare the performance of the C-POD with that of its successor, the F-POD, co-deployed in a field setting for 15 months, to monitor harbour porpoise (Phocoena phocoena). While similar temporal trends in detections were found for both devices, the C-POD detected only 58% of the detection positive minutes (DPM), recorded by the F-POD. Differences in detection rates were not consistent through time making it difficult to apply a correction factor or directly compare results obtained from the two PODs. To test whether these differences in detection rates would have an effect on analyses of temporal patterns and environmental drivers of occurrence, generalised additive models (GAMs) were applied. No differences were found in seasonal patterns or the environmental correlates of porpoise occurrence (month, diel period, temperature, environmental noise, and tide). However, the C-POD failed to detect sufficient foraging buzzes to identify temporal patterns in foraging behaviour that were clearly shown by the F-POD. Our results suggest that the switch to F-PODs will have little effect on determining broad-scale seasonal patterns of occurrence, but may improve our understanding of fine-scale behaviours such as foraging. We highlight how care must be taken interpreting F-POD results as indicative of increased occurrence when used in time-series analysis.
Connectivity maintains the spatial dynamics of metapopulations by promoting dispersal between habitat patches, potentially buffering populations and communities against continued global change. However, this function is threatened by habitats becoming increasingly fragmented, and habitat matrices becoming increasingly inhospitable, potentially reducing the resilience and persistence of populations. Yet, we lack a clear understanding of how reduced connectivity interacts with rates of environmental change to destabilise populations. Using laboratory microcosms containing metapopulations of the Collembola Folsomia candida, we investigate the impact of habitat connectivity on metapopulation persistence under a range of simulated droughts, a key stressor for this species. We manipulated both drought severity and the number of patches affected by drought across landscapes connected by either good or poor-quality corridors. We measured the time of population extinction, the maximum rate of population decline, and the variability of abundance among patches as criteria to evaluate the persistence ability of metapopulations. We show that whilst drought severity and number of drought-affected patches negatively influenced population persistence, these results were mitigated by increased habitat connectivity, which increased population persistence time and decreased both how fast populations declined and the variability in abundance among patches. Our results suggest that enhancing spatial connectivity can increase the persistence of metapopulations, increasing the time available for conservation actions to take effect, and/or for species to adapt or move in the face of continued stress. Given that fragmentation increases the isolation of habitats, improving habitat connectivity by using good quality corridors may provide a useful strategy to enhance the resistance of spatially structured populations.
An important objective of evolutionary biology has always been to grasp the evolutionary and genetic processes that contribute to speciation. The present work provides the first detailed account of the genetic and physiological adaptation to changing environmental temperatures as well as the reasons causing intraspecific divergence in the Eothenomys miletus from the Hengduan mountain (HM) region, one of the biodiversity hotspots. 161 E. miletus individuals from five populations in the HM region had their genomes simplified sequenced, and one additional individual from each community had their genomes resequenced. We then characterized the genetic diversity and population structure of each population and compared the phenotypic divergence in traits using neutral molecular markers. We detected significant phenotypic and genetic alterations in E. miletus from the HM region that were related to naturally occurring diverse habitats by combining morphometrics and genomic techniques. The E. miletus existed asymmetric gene flow patterns, indicating that five E. miletus populations exhibit a isolation-by-island model, and this was supported by the correlation between FST and geographic distance. Finally, PST estimated by phenotypic measures of most wild traits were higher than differentiation at neutral molecular markers, indicating directional natural selection favouring different phenotypes in different populations must have been involved to achieve this much differentiation. Our findings give information on the demographic history of E. miletus, new insights into their evolution and adaptability, and literature for studies of a similar nature on other wild small mammals from the HM region.
Recent declines in eastern wild turkeys (Meleagris gallopavo silvestris) has prompted increased interest in management and research of this important game species. However, the mechanisms underlying these declines are unclear, leaving uncertainty in how best to manage this species. Foundational to effective management of wildlife species is understanding the biotic and abiotic factors that influence demographic parameters and the contribution of vital rates to population growth. Our objectives for this study were to: 1) conduct a literature review to collect all published vital rates for eastern wild turkey over the last 50 years, 2) perform a scoping review of the biotic and abiotic factors that have been studied relative to wild turkey vital rates and highlight areas that require additional research, and 3) use the published vital rates to populate a life-stage simulation analysis (LSA) and identify the vital rates that make the greatest contribution to population growth. Based on published vital rates for eastern wild turkey, we estimated a mean asymptotic population growth rate (λ) of 0.91 (95% CI = 0.71, 1.12). Vital rates associated with after second year (ASY) females were most influential in determining population growth. Survival of ASY females had the greatest elasticity (0.53), while reproduction of ASY females had lower elasticity (0.21), but high process variance, causing it to explain a greater proportion of variance in λ. Our scoping review found that most research has focused on the effects of habitat characteristics at nest sites and the direct effects of harvest on adult survival, while research on topics such as disease, weather, predators, or anthropogenic activity on vital rates have received less attention. We recommend that future research take a more mechanistic approach to understanding variation in wild turkey vital rates as this will assist managers in determining the most appropriate management approach.
Carnivores participate in forest disturbance recovery by dispersing the seeds that pass through their digestive systems. The objective of this study was to evaluate the capacity of mammals for Juniperus deppeana seed dispersal with an experimental evaluation of endozoochory and diploendozoochory, through indices of recovery, viability, changes in testas, and retention of seeds in the digestive tract. Juniperus deppeana fruits were collected in the Sierra Fría Natural Protected Area, Aguascalientes, Mexico, and were administered in the diet of gray fox (Urocyon cinereoargenteus), coati (Nasua narica) and domestic rabbits (Oryctolagus cuniculus) these three mammals represented the endozoochory. For the diploendozoochory, seeds excreted by rabbits were incorporated into the diets of bobcat (Lynx rufus) and cougar (Puma concolor) in a local zoo. The seeds present in the scats were collected, and recovery rates and retention times were estimated; viability was estimated by X-ray optical densitometry, and testa thicknesses and surfaces were checked by scanning electron microscopy. The results showed a recovery of seeds greater than 70% in all the animals; the retention time was < 24 h in the endozoochory, but the time was longer (24-96 h) in the diploendozoochory (P < 0.05). Seed viability (x ̵̅ ± SD) was decreased in rabbits (74.0 ± 11.5 %) compared to fruits obtained directly from the canopy (89.7 ± 2.0 %), while gray fox, coati, bobcat and puma did not affect viability (P < 0.05). An increase in the thickness of the testas was also observed in seeds excreted from all mammals (P < 0.05). Through evaluation, our results suggest that mammalian endozoochory and diploendozoochory contribute to dispersal of J. deppeana by maintaining viable seeds with adaptive characteristics in the testa to promote resilience and forest restoration. In particular, felines (predators) can provide an ecosystem service through scarification and seed dispersal.
Camera traps have 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 using conventional methods. However, manual processing of imagery is extremely time and labor intensive. Because of the associated expense, many studies have started to employ machine learning tools, such as convolutional neural networks (CNNs). One drawback is that for the majority of networks a large number of images (millions) are needed to devise an effective identification or classification model. This study examines 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 environmental factors that make it difficult for even a human observer to classify, including local weather patterns and daylight. We transfer-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, temperature, and image contrast, there was a significant positive association between CNN success and temperature. Furthermore, we found that the model was more successful when images were taken during the day as well as when precipitation was not present. We show that external variables at camera trap locations have a noticeable effect on CNN accuracy. Qualitative site-specific factors can confuse quantitative classification algorithms such as CNNs. This study suggests that further exploration into the causes of error in classification modeling is necessary given the unique challenges posed by the analysis of camera trap imagery.
Seed dormancy contributes greatly to successful establishment and community stability and shows large variation over a continuous status scale in mountain ecosystems. Although empirical studies have shown that seed dormancy status (SDS) is shaped by elevation and phylogenetic history in mountain ecosystems, few studies have quantified their combined effects on SDS. Here, we collected mature seeds from 51 populations of 11 Impatiens species (Balsaminaceae) along an elevational gradient in the Gaoligong Mountains of southwest China and downloaded 19 bioclimatic variables from WorldClim v.2.1 for each Impatiens population. We used internal transcribed spacer (ITS), atpB-rbcL, and trnL-F molecular sequences from the GenBank nucleotide database to construct a phylogenetic tree of the 11 species of Impatiens. SDS was estimated using mean dormancy percentage of fresh seeds germinated at three constant temperatures (15, 20, and 25 °C). Logistic regression model analysis was performed to quantify the effects of phylogeny and environment on SDS. Results showed that there was a significant phylogenetic signal of SDS in the Impatiens species. Furthermore, elevation and phylogeny accounted for 63.629% of the total variation in SDS among the Impatiens populations. The logistic model indicated that climatic factors accounted for 20.832% of the total variation in SDS among the Impatiens species, and model residuals were significantly correlated with phylogeny, but not with elevation. Our results indicated that seed dormancy is phylogenetically conserved, and climate drives elevational patterns of SDS variation in mountain ecosystems. This study provides new insights into the response of seed plant diversity to climate change.
Quantifying spatiotemporally explicit interactions within animal populations facilitates the understanding of social structure and its relationship with ecological processes. Data from animal tracking technologies (Global Positioning Systems [“GPS”]) can circumvent longstanding challenges in the estimation of spatiotemporally explicit interactions, but the discrete nature and coarse temporal resolution of data mean that ephemeral interactions that occur between consecutive GPS locations go undetected. Here, we developed a method to quantify individual and spatial patterns of interaction using continuous-time movement models (CTMMs) fit to GPS tracking data. We first applied CTMMs to infer the full movement trajectories at an arbitrarily fine temporal scale before estimating interactions, thus allowing inference of interactions occurring between observed GPS locations. Our framework then infers indirect interactions – individuals occurring at the same location, but at different times– while allowing the identification of indirect interactions to vary with ecological context based on CTMM outputs. We assessed the performance of our new method using simulations and illustrated its implementation by deriving disease-relevant interaction networks for two behaviorally differentiated species, wild pigs (Sus scrofa) that can host African Swine Fever and mule deer (Odocoileus hemionus) that can host Chronic Wasting Disease. Simulations showed that interactions derived from observed GPS data can be substantially underestimated when temporal resolution of movement data exceeds 30-minute intervals. Empirical application suggested that underestimation occurred in both interaction rates and their spatial distributions. CTMM-Interaction method, which can introduce uncertainties, recovered the majority of true interactions. Our method leverages advances in movement ecology to quantify fine-scale spatiotemporal interactions between individuals from lower temporal resolution GPS data. It can be leveraged to infer dynamic social networks, transmission potential in disease systems, consumer-resource interactions, information sharing, and beyond. The method also sets the stage for future predictive models linking observed spatiotemporal interaction patterns to environmental drivers.
1. Researchers generally ascribe demographic drivers in a single or few sub-populations and presume they are representative. With this information, practitioners implement blanket conservation measures across metapopulations to reverse declines. However, such approaches may not be appropriate in circumstances where sub-populations are spatiotemporally segregated and exposed to different environmental variation. 2. The Greenland White-fronted Goose Anser albifrons flavirostris is an Arctic-nesting migrant that largely comprises two sub-populations (delineated by northerly and southerly breeding areas in west Greenland). The metapopulation has declined since 1999 but this trend is only mirrored in one sub-population and the causes of this disparity are unclear. Here we compare the drivers and trends of productivity in both sub-populations using population- and individual-level analysis. 3. We examined how temperature and precipitation influenced population-level reproductive success and whether there was a change in the relationship when metapopulation decline commenced. In addition we used biologging devices to reconstruct incubation events and modelled how phenology and environmental conditions influenced individual-level nest survival. 4. Correlations between reproductive success and temperature/precipitation on the breeding grounds have weakened for both sub-populations. This has resulted in lower reproductive success for the northerly, but not southerly breeding sub-population, which at the individual-level appears to be driven by lower in nest survival. Earlier breeding ground arrival and less precipitation during incubation increased nest survival in the northerly breeding population, while no factors examined were important for the southerly breeding sub-population. This suggests reproductive success is now driven by different factor(s) in the two sub-populations. 5. Demographic rates and their environmental drivers differ between the sub-populations examined here and consequently we encourage further decomposition of demography within metapopulations. This is important for conservation practitioners to consider as bespoke conservation strategies, targeting different limiting factors, may be required for different sub-population.
Earthworms modulate the carbon and nitrogen cycling in terrestrial ecosystems, their effect may be affected by deposited compounds due to human activity such as industrial emissions. However, studies investigating how deposited compounds affect the role of earthworms in carbon cycling such as litter decomposition are lacking, although they are important for understanding the influence of deposited compounds on ecosystems and the bioremediation by applying earthworms. For this, we performed a 365-day in situ litterbag decomposition experiment in a deciduous (Quercus variabilis) and coniferous (Pinus massoniana) forest in southeast China. We manipulated nitrogen (N), sodium (Na) and polycyclic aromatic hydrocarbon (PAH) deposited compounds during litter decomposition with and without earthworms (Eisenia fetida). After one year, N, Na and PAH compounds all slowed down litter mass loss, with the effects of Na being the strongest. By contrast, E. fetida generally increased litter mass loss and their positive effects were uniformly maintained irrespective of the type of deposited compounds. Further, the pathways earthworms increasing litter mass loss varied among the types of deposited compounds and forests. As indicated by structural equation modeling, earthworms maintained their positive effects and mitigated the negative effects of deposited compounds by directly increasing litter mass loss and indirectly increasing soil pH and microbial biomass. Overall, the results indicate that the acceleration of earthworms on litter mass loss is not affected by deposited compounds, with the pathways of earthworms increasing litter mass loss varying among the types of deposited compounds and forests. This suggests that the effects of atmospheric deposited compounds and earthworms on terrestrial ecosystem processes need to be taken into account because earthworms may cancel out the detrimental influence of deposited compounds on litter decomposition.