Biological invasions are recognized as one of the factors causing biodiversity loss. Incomplete reproductive isolation with a closely related species can result in hybridization when a non-native species is introduced into a new habitat. Management of hybrids is essential for biodiversity conservation; however, the distinction between the two species becomes a challenge in cases of hybrids with similar characteristics to native species. Although image recognition technology can be a powerful tool for identifying hybrids, studies have yet to utilize deep learning approaches. Hence, this study aimed to identify hybrids between native Japanese giant salamanders (Andrias japonicus) and non-native Chinese giant salamanders (Andrias davidianus) using EfficientNet and smartphone images. We used smartphone images of 11 native individuals (with 5 training and 6 test images) and 20 hybrid individuals (with 5 training and 15 test images). In our experimental environment, an AI model constructed with efficientNet-V2 showed 100% accuracy in identifying hybrids. In addition, highlighting the regions that influenced the AI model’s predictions using Grad-CAM revealed that salamander head spots are responsible for correctly classifying native and hybrid species. The results of this study revealed that our approach is one of the methods that enable the identification of hybrids, which was previously considered difficult without identification by the experts. Furthermore, since this study achieved high-performance identification using smartphone images, it is expected to be applied to a wide range of low-cost identification using citizen science.
As climate changes, understanding the genetic basis of local adaptation in plants becomes an ever more pressing issue. Combining Genotype-Environment Association (GEA) with Genotype-Phenotype Association (GPA) analysis has an exciting potential to uncover the genetic basis of environmental responses. We use these approaches to identify genetic variants linked to local adaptation to drought in Pinus ponderosa. Over 4 million SNPs were identified using 223 individuals from across the Sierra Nevada of California. We found 1458 associated with five largely uncorrelated climate variables, with the largest number (1151) associated with April 1st snowpack. We also conducted a greenhouse study with various drought-tolerance traits measured in seedlings grown in control and drought treatments. 817 SNPs were associated with control-condition trait values, while 1154 were associated with responsiveness of these traits to drought. While no individual SNPs were associated with both the environmental variables and the measured traits, several annotated genes were associated with both, particularly those involved in cell wall formation, biotic and abiotic stress responses, and ubiquitination. However, the functions of many of the associated genes have not yet been determined due to the lack of gene annotation information for conifers. Future studies are needed to assess the developmental roles and ecological significance of these unknown genes.
Information on freshwater mussel behavior in the sediment is scarce in the Neotropics, especially in the Amazon. Laboratory experiments were used to measure the responses of the mussel Castalia ambigua in relation to combinations of two different morphotypes (Morphotype I with an elongated shell and Morphotype II with a rounded shell) and three different densities (4, 8 and 16 mussels). Horizontal movements (cm) were calculated by summing changes in the position of each specimen and the shell exposure at the sediment-water interface was obtained by measuring (mm) the exposed part of the shell. Castalia ambigua presents different patterns of shell exposure and horizontal movements linked with shell shape and density. Castalia ambigua Morphotype I remained less exposed with 4 mussels. In contrast, this morphotype was more exposed and tended to aggregate in treatments with 8 and 16 mussels, similar to observations of Morphotype II at all densities. Morphotype II is mainly found in low hydrodynamic energy habitats, suggesting that patches with high densities may stabilize the substrate around the shells of Morphotype I, which is associated with high hydrodynamic energy habitats. We suggest that these patterns may be associated with intrinsic factors of the species, such as reproduction and feeding. Moreover, additional studies using other mussel species belonging to the families Hyriidae and Mycetopodidae are important, since the behavior of these mussels in the sediment may provide useful information on their functional roles in river ecosystems.
A better understanding of the impact of habitat loss on population density can be achieved by evaluating effects of both, parameters within remnant habitat patches and parameters of the landscape surrounding those patches. The integration of predictors at the patch and landscape level is scarce in animal ecological studies, especially for reptiles. In this study, a patch-landscape approach was applied to evaluate the combined effects of within patch habitat quality, patch geometry and landscape configuration and composition on the density of remnant populations of the eastern green lizard, Lacerta viridis, in a highly modified landscape in Bulgaria. Landscape composition variables (proportion of different land covers) were measured at different spatial scales surrounding patches. Single scale models were built to evaluate combined effects of all predictors on density, when including all landscape composition variables at a specific spatial scale. Multiscale models were applied to analyze combined effects when including landscape composition variables at the scale of their strongest effect (scale of effect, SoE). Results showed that the SoE of proportion of cropland and urban areas was small (50 m), while for proportion of habitat was large (1.5 Km). The overall effect of habitat loss was better explained by the multiscale model. Population density increased with patch area and decreased with patch shape irregularity and with the proportion of three land cover types surrounding patches -cropland, urban areas and habitat. Combining patch and landscape parameters is important to identify ecological processes that occur simultaneously at different spatial levels and landscape scales, and which would imply the application of multiscale approaches for the protection of wild animal populations. Results are contrasted with what is known about occupancy patterns of the species in the same region, and approaches to integrate both, occupancy and density, in the field design of animal ecological studies are suggested.
The purpose of inter-animal communication is to allow signals released by the animal to be perceived by others. Scent marking, with its characteristics of specificity and delay, is thought to be the primary mode of communication in giant pandas (Ailuropoda melanoleuca). The “signal detection theory” predicts that animals choose the substrate and location of their scent marks so that the signals released are transmitted more widely and remain longer. As an energetically marginal species, the cost of generating and marking chemical signals is costly for pandas, so they are predicted to make trade-offs in scent marking. However, existing studies do not account for the selective preferences of pandas for marking, as they are only explained by the density of marks at a certain location. Our study wanted to investigate whether the marking behavior of pandas is indeed consistent with signal detection theory. For the first time, we propose to use fecal counts to reflect the intensity of habitat use by pandas, combined with mark counts to determine the selective preference for marking. Our findings show that the scent marking behavior of pandas is consistent with signal detection theory, and that they go out of their way to ensure that their marks are detected. The results of the study will help us to further develop the conservation of pandas and their habitats.
Increasing studies have shown the importance of intraspecific trait variation (ITV) on the ecological process. However, the patterns and sources of ITV are still unclear, especially in the propagule of coastal vegetation. Here, we measured fresh weight (FW), fresh length (FL), maximum transverse diameter (TDmax), minimum transverse diameter (TDmin) and the ratio of TDmax to TDmin (RTD) of the hypocotyl (propagule) of Kandelia obovata for 66 genealogies across 26 sites. By combining multiple factors of climate, ocean and maternal tree to analyze their effects on the intraspecific trait variation of mangrove hypocotyl. The results showed that value of establishment traits (FW, FL, TDmax and TDmin which are related to mass) decreased along increasing latitudinal gradients and they were directly positively regulated by temperature. ITV of dispersal trait (RTD) was unstructured along latitudinal gradients, which was constrained by fitness tradeoff. Our findings indicate that establishment traits mainly varied between populations, whereas dispersal traits mainly varied between individuals. This study provides insights into the ITV of propagule in different functional dimensions on a broad scale and that may help integrate ITV into future analyses of mangrove protection.
The Whooping Crane (Grus americana; WHCR) is a large, long-lived bird endemic to North America. The remnant population migrates between Aransas National Wildlife Refuge, USA, and Wood Buffalo National Park, Canada (AWBP), and has recovered from a nadir of 15-16 birds in 1941 to ~540 birds in 2022. Two ongoing reintroduction efforts in Louisiana and the Eastern Flyway together total ~150 birds. Evidence indicates the U.S. Fish and Wildlife Service (USFWS) is strongly considering downlisting the species from an endangered to a threatened status under the Endangered Species Act (ESA). We examined the current status of the WHCR through the lens of ESA threat factors, the USFWS’s Species Status Assessment (SSA) framework, and other avian downlisting actions to determine if the action is biologically warranted. Our research indicates that WHCRs are facing an intensification of most threat drivers across populations and important ranges. The AWBP is still relatively small compared to other crane species and most birds of conservation concern. To date, only one avian species has been downlisted from an endangered status with an estimated population of <3,000 individuals. Representation in terms of WHCRs historic genetic, geographic, and life history variation remains limited. Also, the lack of spatial connectivity among populations, reliance of the reintroduced populations on supplementation, and continued habitat loss suggest that WHCR populations may not be resilient to large stochastic disturbances. Given that reintroduced populations are not self-sustaining, neither supplies true redundancy for the AWBP. Proposed downlisting before recovery plan population criteria have been met is objectively unwarranted and reflects USFWS inconsistency across ESA actions. Only by incorporating basic quantitative criteria and added oversight into ESA listing decisions can we avoid an action as misguided as downlisting the Whooping Crane without consideration of its recovery plan criteria or ostensibly its population ecology.
Sharks, rays and chimaera form the clade Chondrichthyes, an ancient group of morphologically and ecologically diverse vertebrates that has played an important role in our understanding of gnathostome evolution. Increasingly studies have are seeking to investigate evolutionary processes operating within the chondrichthyan crown group, with the broad aim of understanding the driving forces behind the vast phenotypic diversity observed amongst its constituent taxa. Genetic, morphological and behavioural studies have all contributed to our understanding of phenotypic evolution yet are typically considered in isolation in the context of Chondrichthyes. I argue that integrating these core fields of organismal biology is vital if we are to understand the evolutionary processes operating in contemporary chondrichthyan taxa, and how such processes have contributed to past phenotypic evolution. In light of the global extinction crisis facing this clade, this understanding is crucial if we are to successfully conserve rapidly declining chondrichthyan populations.
Worldwide climate-driven shifts in the distribution of species is of special concern when it involves habitat-forming species. In the coastal environment, large Laminarian algae – kelps – form key coastal ecosystems that support complex and diverse food webs. Among kelps, Macrocystis pyrifera is the most widely distributed habitat-forming species and provides essential ecosystem services. This study aimed to establish the main drivers of future distributional changes on a global scale and use them to predict future habitat suitability with a focus on the southeastern Pacific coast. Using species distribution models (SDM), we examined the changes in global distribution of M. pyrifera under different emission scenarios. To constrain the drivers of our simulations to the most important factors controlling kelp forest distribution across spatial scales, we explored a suite of environmental variables and validated the predictions derived from the SDMs. Minimum sea surface temperature was the most important variable explaining the global distribution of suitable habitat for M. pyrifera. Under different climate change scenarios, we always observed a decrease of suitable habitat at low latitudes, while an increase was detected in other regions, mostly at high latitudes. Along the southeast Pacific, we observed a range contraction of 14.5◦ of latitude for 2100 under the RCP 8.5 scenario, implying a loss of habitat suitability throughout the coast of Peru and poleward to 27.83◦S in Chile. On the northern coast of Chile, the area coinciding with the complete habitat loss predicted by our model is under heavy exploitation with over 11,180 tons harvested every year from natural populations of M. pyrifera. The loss of habitat suitability will likely have significant impacts on marine biodiversity and ecosystem functioning and is a harbinger of massive impacts in the socio-ecological systems of the southeastern Pacific.
The biogeography research of orchids through species distribution models (SDMs), a vital tool in the biogeography field, is critical to understanding the fundamental geographic distribution patterns and identifying conservation priorities. The correspondence between species occurrence and environmental information is crucial to the model’s performance. However, ecological preferences unique to different orchid species, such as their life forms, are often overlooked during the modeling process. This oversight can introduce bias and increase model uncertainty. Additionally, human activities, as an important potential predictor, have not been quantified in any orchid SDMs. Taking the Hengduan Mountains as an example, we preprocessed all orchid species’ occurrences based on physiological characteristics. Choosing five spatial factors related to human activities to quantify the interference and enter into models as HI factor. Using different modeling methods (GLM, MaxEnt, and RF) and evaluation indices (AUC, TSS, and Kappa), diverse modeling strategies have been constructed in the study. A double-ranking method has been adopted to select the critical orchid distribution regions. The results showed that classification models based on physiological characteristics significantly improved the model’s accuracy while adding the HI factor had the same effect but the absence of enough significance. Suitability maps indicated that highly heterogeneous mountainous areas were vital for the distribution of orchids in the Hengduan Mountains. Different distribution patterns and critical regions existed between various orchid life forms geographically - terrestrial orchids were dominant in the mountain, and mycoherterophical orchids were primarily located in the north, more influenced by vegetation and temperature. Critical regions of epiphytic orchids were in the south due to a greater dependence on precipitation and temperature. These studies are informative for understanding the orchids’ geographic distribution patterns in the Hengduan Mountains, promoting conservation, and providing references for similar research beyond orchids.
1. Ice coverage duration on lakes and ponds is decreasing due to climate change, but experimentally testing the effects of decreased ice coverage on aquatic communities is challenging in field settings. 2. To assess whether we could simulate changes predicted to occur in aquatic habitats as climate change progresses including shorter ice duration, warmer temperatures, and thinner ice and associated water chemistry changes, we designed and constructed greenhouses to place over a set of ten experimental ponds, roughly 3x3m in area which slope to a maximum depth of 1m, dug into the ground at the Koffler Scientific Reserve (Ontario, Canada). Half of the wedge-shaped greenhouses were enclosed on all sides (n=5) while the other the other half were open on three sides, with only the top fitted with plastic sheeting (n=5). The open greenhouses provided a less-warmed treatment while controlling for precipitation reduction and light filtering caused by the sheeting. In November 2019 greenhouses were placed over the ponds. Snow was cleared from the greenhouses and water chemistry measures were taken once weekly through the 2019-2020 winter. 3. Ice was thinner across the winter and melted on average 10.6 days earlier in closed greenhouses compared to open greenhouses. Average winter water temperatures were also significantly higher in closed versus open greenhouses although these differences were not significant in all months. Similarly, maximum and minimum water temperatures were also higher in ponds with closed compared with open greenhouses. We successfully demonstrate a method for simulating expected changes in ice conditions as climate change progresses including decreasing ice coverage duration at levels similar to those observed in north temperate ecosystems (per century) and alpine ecosystems (per 36 years) and raising temperatures in a highly manipulatable experimental system.
Changing climate and growing human impacts are resulting in globally rising temperatures and the widespread loss of habitats. How species will adapt to these changes is not well understood. The Northern Goshawk (Accipiter gentilis) can be found across the Holarctic but is coming under more intense pressure in many places. Studies of recent populations in Finland and Denmark have shown a marked decline in body size of Northern Goshawks over the past century. Here we investigate long-term changes to Norwegian populations of Northern Goshawk by including material from the Middle Ages and Viking Age. We measured 240 skeletons of modern Northern Goshawks from Norway, Sweden, Denmark and Finland, and 89 Medieval Goshawk bones. Our results show that Norwegian and Swedish female Goshawks have decreased in size over the past century, whilst males showed little decline. Medieval female Goshawks were larger than contemporary females. The Viking Age specimens showed little difference to modern populations but appeared smaller than specimens from the Medieval period. A decline in forest habitats and a concomitant shift towards smaller prey likely drove a shift to smaller body size in Northern Goshawks. Our study shows that significant body size changes in birds can occur over relatively short time spans in response to environmental factors, and that these effects can sometimes differ between sexes.
The extended phenotype of helical burrowing behavior in animals has evolved independently many times since first appearing after the Cambrian explosion (~540 million years ago). A number of hypotheses have been proposed to explain the evolution of helical burrowing in certain taxa, but no study has searched for a general explanation encompassing all taxa. We reviewed helical burrowing in both extant and extinct animals and from the trace fossil record and compiled from the literature 10 possible hypotheses for why animals construct helical burrows, including our own ideas. Of these, six were post-construction hypotheses—-benefits to the creator or offspring, realized after burrow construction—-and four were construction hypotheses reflecting direct benefits to the creator during construction. We examined the fit of these hypotheses to a total of 21 extant taxa and ichnotaxa representing 59–184 spp. Only two hypotheses—-antipredator, biomechanical advantage—-could not be rejected for any species (possible in 100% of spp.), but six of the hypotheses could not be rejected for most species (possible in 86–100 % of spp.): microclimate buffer, reduced falling sediment (soil), anticrowding, vertical patch, and the above two hypotheses. Four of these six were construction hypotheses, raising the possibility that helical burrowing might have evolved without providing post-construction benefits. Our analysis showed that increased drainage, deposit feeding, microbial farming, and offspring escape could not explain helical burrowing behavior in the majority of taxa (5–48%). Overall, the evidence does not support a general explanation for the evolution of helical burrowing in animals. The function and evolution of the helix as an extended phenotype would seem, at least in some cases, to provide different advantages for different taxa. Although direct tests of many of the hypotheses would be difficult, we nevertheless offer ways to test some of the hypotheses for selected taxa.
Eucalyptus snout beetles (Curculionidae: Gonipterus scutellatus complex), native to mainland Australia and Tasmania, defoliate Eucalyptus trees and are considered important pests. Since the 19th century, species of the G. scutellatus complex have been introduced to other continents. Here, we document the presence of Eucalyptus snout beetles in Ecuador and use ecological niche models to analyze their potential distribution in South America. Phylogenetic analyses of DNA sequences unambiguously demonstrated that the Ecuadorian specimens belong to the species G. platensis, which has low genetic diversity compared with other species in the complex. Ecological niche models revealed several areas of high to intermediate climatic suitability for the pest in South America, even in countries where it has not been registered, like Peru and Bolivia. Accurate identification of species in the Gonipterus scutellatus complex and understanding of their potential distribution are essential tools for improved management and prevention tactics.
Urbanization and the expansion of human activities foster radical ecosystem changes with cascading effects also involving host-pathogen interactions. Urban pollinator insects face several stressors related to landscape and local scale features such as green habitat loss, fragmentation, and availability reduction of floral resources with unpredictable effects on parasite transmission. Furthermore, beekeeping may contribute to the spread of parasites to wild pollinators by increasing the number of parasite hosts. Here we used DNA-based diagnostics tools to evaluate how the occurrence of parasites, namely microsporidians (Nosema spp.), trypanosomatids (Crithidia spp.) and neogregarines (Apicystis bombi), is shaped by the above-mentioned stressors in two bumblebee species (i.e, Bombus terrestris and B. pascuorum). Infection rates of the two species were different and generally higher in B. terrestris. Moreover, they showed different responses towards the same ecological variables, possibly due to differences in body size and foraging habits supposed to affect their susceptibility to parasite infection. The probability of infection was found to be reduced in B. pascuorum by green habitat fragmentation, while increased along with floral resource availability. Unexpectedly, B. terrestris had a lower parasite richness nearby apiaries probably because parasites are prone to be transmitted among the most abundant species. Our finding supports the need to design proper conservation measures based on species-specific knowledge, as suggested by the variation in the parasite occurrence of the two species. Moreover, conservation policies aiming at safeguarding pollinators through flower planting should consider the indirect effects of these measures for parasite transmission together with pollinator biodiversity issues.
1. Otoliths have been widely studied as natural recorders of the entire life cycle of aquatic teleosts. Trace elements and stable isotope rations in otoliths are well understood and used as proxies of migration histories, however few elements have shown the potential to reconstruct the migration history of oceanodromous fish. 2. This study reports the first use of radiocarbon in otolith to reconstruct the horizontal migration history of fish. We analyzed three different stocks of walleye pollock Gadus chalcogrammus around Hokkaido, Japan. 3. Radiocarbon concentration from the outermost edge of otoliths showed a general consistency with seawater radiocarbon concentration of the sampling region, validating the application of otolith radiocarbon concentration to fish migration studies. Pollocks of all three stocks generally inhabited the nearby sampling area throughout their life cycle, though some pollocks of the Okhotsk and Japan Sea stocks respectively showed a possibility of migration between different sea regions. 4. This study confirmed a novel method using radiocarbon concentrations to reconstruct the migration history of marine teleost. Using the high sensitivity of otolith radiocarbon concentration observed in this study, it may be possible to detect fish migration with higher spatial resolution than previous studies using conventional proxies.
Monitoring the effect of ecosystem restoration can be difficult and time consuming. Autonomous sensors, such as acoustic recorders, can aid monitoring across long time scales. This project successfully developed, tested and implemented call recognisers for eight species of frog in the Murray-Darling Basin. Recognisers for all but one species performed well and substantially better than many species recognisers reported in the literature. We achieved this through a comprehensive development phase, which carefully considered and refined the representativeness of training data, as well as the construction (amplitude cut-off) and the similarity thresholds (score cut-offs) of each call template used. Recogniser performance was high for almost all species examined. Recognisers for C. signifera, L. fletcherii, L. dumerilii, L. peronii, and C. parinsignifera all performed well, with most templates having ROC values (the proportion of true positive and true negatives) over 0.7, and some much higher. Recognisers for L. peronii, L. fletcherii and L. dumerilii performed particularly well in the training dataset, which allowed for responses to environmental watering events, a restoration activity, to be clearly observed. While slightly more involved than building recognisers using commercial packages, the workflows ensure that a high quality recogniser can be built and the performance fine-tuned using multiple parameters. Using the same framework, recognisers can be improved in future iterations. We believe that multi-species recognisers are a highly effective and precise way to detect the effects of ecosystem restoration.
The increasing availability of satellite imagery has supported a rapid expansion in forward-looking studies seeking to track and predict how climate change will influence wild population dynamics. However, these data can also be used in retrospect to provide additional context for historical data in the absence of contemporaneous environmental measurements. We used 167 Landsat-5 Thematic Mapper (TM) images spanning 13 years to identify environmental drivers of fitness and population size in a well-characterized population of banner-tailed kangaroo rats (Dipodomys spectabilis) in the southwestern United States. Overall, we found that our specific ecological predictions regarding relationships between environmental measures calculated from Landsat TM data and population demographic trends were supported by our results. However, for surface temperature, we found evidence of two decoupled processes that may be driving population dynamics in opposing directions over distinct time frames. These relationships would not have been identified in the absence of remotely sensed data, indicating that such information can be used to test existing hypotheses and generate new ecological predictions regarding fitness at multiple spatial scales and degrees of sampling effort. To our knowledge, this study is the first to directly link remotely sensed environmental data to individual fitness measures, opening a new avenue for incorporating remote sensing data into eco-evolutionary studies.