Montane birds experience a range of challenges that may limit their breeding success, including nest predation and severe climactic conditions. The continuing effects of climate change are causing shifts in biotic and abiotic factors that may compound these threats to montane bird species. In northeastern montane forests, many bird species are shifting downslope, potentially as the result of increased precipitation and temperature at higher elevations. Although lower elevations might be more favorable in terms of climactic conditions, nest predation is higher at lower elevations. Thus, montane birds might be faced with the opposing pressures of adverse climactic conditions at higher elevations and increased predation at lower elevations. We monitored nests of Swainson’s thrush (Catharus ustulatus) along an elevation gradient in the White Mountain National Forest in New Hampshire in 2016, 2018, 2019 and 2021 to examine the effect of biotic and abiotic factors on nest survival. We found a significant negative effect of rain intensity (millimeters per hour per day) on daily nest survival, suggesting that heavier rain per hour decreases Swainson’s thrush daily daily nest survival. Moreover, we found a negative interaction effect of elevation in conjunction with minimum daily temperature and average daily temperature, suggesting that at higher elevations, temperature, specifically on colder days, decreases Swainson’s thrush nest survival. Our results provide evidence for a potential mechanism of how climate change will affect nesting survival of montane breeding birds as heavier precipitation events become more frequent and intense, a likely outcome due to the changing climate within the White Mountains and other montane ecosystems, putting other passerine species at risk in this system.
Many reef invertebrates reproduce through simultaneous broadcast spawning, with an apparent advantage of overwhelming potential predators and maximizing propagule survival. Although reef fish have been observed to consume coral gamete bundles during spawning events, there are no published records of such predation by benthic invertebrates. Here, we document several instances of the ruby brittle star, Ophioderma rubicundum, capturing and consuming egg-sperm bundles of the mountainous star coral, Orbicella faveolata, and the symmetrical brain coral, Pseudodiploria strigosa, during spawning events in the Cayman Islands in 2012 and the Florida Keys in 2022. These observations are widely separated in space and time (>600 km, 10 years), suggesting that this behavior may be ubiquitous on western Atlantic reefs. Since O. rubicundum spawns on the same or subsequent nights as these coral species, we hypothesize that this opportunistic feeding behavior takes advantage of the coral’s lipid-rich bundles to recover energy reserves expended by the brittle star during gametogenesis. The consumption of coral gametes by adult brittle stars suggests a novel trophic link between reef invertebrates, and also provides evidence that ophiuroid-coral symbioses may oscillate between commensalism and parasitism depending on the ontogeny and reproductive status of both animals. Our observations provide insights into the nuanced, dynamic associations between coral reef invertebrates and may have implications for coral fecundity and resilience.
Avian diet can be affected by site-specific variables, such as habitat, as well as intrinsic factors such as sex. This can lead to dietary niche separation, which reduces competition between individuals, as well as impacting how well avian species can adapt to environmental variation. Estimating dietary niche separation is challenging, due largely to difficulties in accurately identifying food taxa consumed. Consequently, there is limited knowledge of the diets of woodland bird species, many of which are undergoing serious population declines. Here, we show the effectiveness of multi-marker faecal metabarcoding to provide in-depth dietary analysis of a declining passerine, the Hawfinch (Coccothraustes coccothraustes). We collected faecal samples from (n=262) UK Hawfinches prior to, and during the breeding seasons in 2016-2019. We detected 49 and 90 plant and invertebrate taxa, respectively. We found Hawfinch diet varied spatially, as well as between sexes, indicating broad dietary plasticity and the ability of Hawfinches to utilise multiple resources within their foraging environments.
To predict suitable growing regions for Leonurus japonicus and to provide scientific sopport for the habitat conservation and the exploitation and utilization of germplasm resources under climate change conditions, this study combined niche and priority conservation models to assess the future potential distribution of L. japonicus in China. To this end, distribution points and samples of L. japonicus were gathered through online and field surveys. The Maxent model with optimized parameters was used for predicting the suitable habitats of L. japonicus at different stages, and the Marxan model was used to determine the priority of protected areas. The results showed that the highest temperature in the hottest month, the lowest temperature in the coldest month, the precipitation in the wettest month, the precipitation in the driest month, and altitude were the main environmental factors influencing the distribution of L. japonicus. Under the three climate change scenarios, the centroid of the suitable area of L. japonicus migrated northward, and the migration position tended to expand further northwest. In the future, there would be no significant niche differentiation of L. japonicus; the Marxan results showed that priority protected areas for L. japonicus were in southwestern central China, Lingnan, southern east China, and Guizhou. Overall, the results of this research can provide a strategy for the determination of priority protection areas for Leonurus japonicus in China.
The interaction of recent orographic uplift and climate heterogeneity acted as a key role in the East Himalaya-Hengduan Mountains (EHHM) has been reported in many studies. However, how exactly the interaction promotes clade diversification remains poorly understood. Here, we both studied genetic structure of the chloroplast trnT-trnF region and 11 nuclear microsatellite loci in Hippophae gyantsensis and examined what role geological barriers or ecological factors play in the spatial genetic structure. The results showed that this species had a strong east-west phylogeographic structure, with several mixed populations identified from microsatellite data in central location. The intraspecies divergence time was estimated to about 3.59 Ma, corresponding well with the recent uplift of the Tibetan Plateau. Between the two lineages there was significant climatic differentiation without geographic barriers. High consistency between lineage divergence, climatic heterogeneity and Qingzang Movement demonstrated that climatic heterogeneity but not geographic isolation drives the divergence of H. gyantsensis, and the recent regional uplift of the QTP, as the Himalayas, create heterogeneous climates by affecting the flow of the Indian monsoon. The east group of H. gyantsensis experienced population expansion c. 0.12 Ma, closely associated with the last interglacial interval. Subsequently, a genetic admixture event between east and west groups happened at 26.90 ka, a period corresponding to the warm inter-glaciation again. These findings highlight the importance of the Quaternary climatic fluctuations in the recent evolutionary history of H. gyantsensis. Our study will improve the understanding of the history and mechanisms of biodiversity accumulation in the EHHM region.
Seasonal dietary shifts of animals are important ecological adaptation strategies. An increasing number of studies have shown that seasonal dietary shifts can influence or even determine the composition of gut microbiota. The turpan wonder gecko Teratoscincus roborowskii lives in extreme desert environments, which have flexible dietary shift to fruit-eating in warm seasons. But the impact of such shifts on gut microbiota is poorly understood. Here, 16SrRNA sequencing and LC-MS metabolomics we used to examine the changes of gut microbiota composition and metabolic pattern of T. roborowskii. The results demonstrated that the gut microbes of T. roborowskii had significant seasonal changes, the diversity and abundance of gut microbiota in autumn were higher than those of in spring. Firmicutes, Bacteroidetes and Proteobacteria were the core gut microbes of T. roborowskii. Verrucomicrobia and Proteobacteria exhibit dynamic pattern of ebb and flow between spring and autumn.The composition and structure of gut microbes in different seasons perform specific metabolic functions, and this change may be an important adaptation for T. roborowskii to cope with dietary shifts and improve energy acquisition. Our study will provide a theoretical basis for exploring the adaptive evolution to special frugivorous behavior of the T. roborowskii, which is an important supplement to the study of the gut microbiology of desert lizards.
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.