Extinction Risk Research Articles

Examining elevation and thermoregulatory trait differences of endemic tropical swallowtail butterflies to assess their vulnerability to climate change

Abstract Tropical montane insects are vulnerable to climate change if up‐hill range retractions reduce range sizes and increase extinction risk. Endemic species will be particularly at risk if they disproportionately occur at higher elevations, although threats may be ameliorated if they have morphological traits associated with improved thermoregulatory ability. We examine the vulnerability of endemic swallowtail butterflies on Sulawesi (Indonesia) to climate change by quantifying inter‐specific variation in traits associated with thermoregulation (body size and melanism) and whether species' traits are associated with the elevation of species' ranges. We collected data on size, melanism and elevation of 29 swallowtail butterfly species (Lepidoptera: Papilionidae) from 754 specimens at the Natural History Museum (United Kingdom) and the Zoologische Staatssammlung München (Germany). Endemic butterflies were less melanised (16 endemic species, mean = 83% melanised; 13 non‐endemic species = 89% melanised) but similar to non‐endemics in size (endemic, mean = 56 mm; non‐endemic = 53 mm) and elevation (endemic, mean = 345 m.a.s.l.; non‐endemic: 291 m). There was no evidence that species size or melanism patterns were related to elevation in either group. Few differences in elevation of endemic and non‐endemic species imply that endemic swallowtail butterflies are not disproportionately more threatened by climate‐driven mountaintop extirpation than non‐endemic species. Further work is needed to examine whether paler wings alter the ability of endemic species to thermoregulate and adapt to changing climates. In the absence of reductions in anthropogenic global greenhouse gas emissions, on‐going climate warming will continue to threaten tropical montane species.

Cheniella tsoongii (Leguminosae: Cercidoideae), a rare, critically endangered new species from southern China

We describe here a rare, critically endangered new species of the genus Cheniella from Guangdong province of southern China. Cheniella tsoongii is morphologically similar to C. corymbosa, and can be distinguished by having a combination of deeply-bilobed hairy leaves, white flowers, shorter hypanthia, yellow anthers, and densely ferruginous-tomentose inflorescence rachides, pedicles and hypanthia. We suggest assessing the conservation status of the species as Critically Endangered (CR) as it possesses an extremely high risk of extinction based on the rapid population declines during the last century and, only no more than 10 individuals remain in an environmentally unprotected area now. Urgent conservation studies and actions are necessary to prevent the extinction of this species.

Genetic predictors of population resilience: A case study of native Brook Trout in headwater streams

AbstractObjectivePopulations of eastern Brook Trout Salvelinus fontinalis face threats from several sources, such as habitat fragmentation, climate change, and competition with introduced salmonids. As a native species, understanding how these populations will respond to disturbances is paramount to their management and effective conservation. A population's ability to respond to disturbance, its resilience, is influenced by several factors. One such group of factors is population genetics.MethodsWe calculated population resilience metrics based on transient dynamics using population projection matrix models. Long‐term demographic data from 23 headwater stream Brook Trout populations were used to parameterize models. Genetic data were collected, and genetic indices were calculated. Partial redundancy analysis was then used to evaluate relationships between resilience metrics and genetic indices.ResultInbreeding coefficient, rarefied allelic richness, pairwise genetic differentiation (FST), and effective population size were all found to be important variables in predicting resilience.ConclusionOur results suggest that genetic isolation may increase the demographic resilience in Brook Trout through faster generation times and higher juvenile survival, but this likely comes at the cost of increased extinction risk and truncated size structures. Genetic indices can provide insight into gene flow between populations, thus the relationship between population connectivity and resilience. Given the importance of connectivity to population resilience, restoring and maintaining movement corridors could affect resilience in headwater Brook Trout populations.

Tests of evolutionary and genetic rescue using flour beetles, Tribolium castaneum, experimentally evolved to thermal conditions.

Small, isolated populations are often characterised by low levels of genetic diversity. This can result in inbreeding depression and reduced capacity to adapt to changes in the environment, and therefore higher risk of extinction. However, sometimes these populations can be rescued if allowed to increase in size or if migrants enter, bringing in new allelic variation and thus increasing genetic diversity. This study uses experimental manipulation of population size and migration to quantify their effects on fitness in a challenging environment to better understand genetic rescue. Using small, replicated populations of Tribolium castaneum experimentally evolved to different temperature regimes we tested genetic and demographic rescue, by performing large-scale manipulations of population size and migration and examining fitness consequences over multiple generations. We measured fitness in high temperature (38°C) thermal lines maintained at their usual 'small' population size of N = 100 individuals, and with 'large' scaled up duplicates containing N≈10,000 individuals. We compared these large lines with and without migration (m = 0.1) for 10 generations. Additionally, we assessed the effects of outcrossing at an individual level, by comparing fitness of hybrid (thermal line × stock) offspring with within-line crosses. We found that, at the population level, a rapid increase in the number of individuals in the population resulted in reduced fitness (represented by reproductive output and survival through heatwave conditions), regardless of migration. However, at an individual level, the hybrid offspring of migrants with native individuals generally demonstrated increased longevity in high temperature conditions compared with individuals from thermal selection lines. Overall, these populations showed no evidence that demographic manipulations led to genetic or evolutionary rescue. Following the effects of migration in individuals over several generations may be the next step in unravelling these conflicting results. We discuss these findings in the context of conservation intervention.

Synchrony in adult survival is remarkably strong among common temperate songbirds across France.

Synchronous variation in demographic parameters across species increases the risk of simultaneous local extinction, which lowers the probability of subsequent recolonization. Synchrony therefore tends to destabilize meta-populations and meta-communities. Quantifying interspecific synchrony in demographic parameters, like abundance, survival, or reproduction, is thus a way to indirectly assess the stability of meta-populations and meta-communities. Moreover, it is particularly informative to identify environmental drivers of interspecific synchrony because those drivers are important across species. Using a Bayesian hierarchical multisite multispecies mark-recapture model, we investigated temporal interspecific synchrony in annual adult apparent survival for 16 common songbird species across France for the period 2001-2016. Annual adult survival was largely synchronous among species (73%, 95% credible interval [47%-94%] of the variation among years was common to all species), despite species differing in ecological niche and life history. This result was robust to different model formulations, uneven species sample sizes, and removing the long-term trend in survival. Synchrony was also shared across migratory strategies, which suggests that environmental forcing during the 4-month temperate breeding season has a large-scale, interspecific impact on songbird survival. However, the strong interspecific synchrony was not easily explained by a set of candidate weather variables we defined a priori. Spring weather variables explained only 1.4% [0.01%-5.5%] of synchrony, while the contribution of large-scale winter weather indices may have been stronger but uncertain, accounting for 12% [0.3%-37%] of synchrony. Future research could jointly model interspecific variation and covariation in breeding success, age-dependent survival, and age-dependent dispersal to understand when interspecific synchrony in abundance emerges and destabilizes meta-communities.

Searching for nature-based solutions: Molecular ecology of an endangered Himalayan medicinal herb shows roadmap for conservation and sustainable utilization

In recent times, to meet the surging demand of the herbal industry, overharvesting of medicinal herbs from their natural habitats has accelerated. This has posed severe extinction risks to plant species worldwide and therefore requires urgent conservation efforts and long-term sustainable solutions. By employing a molecular ecology approach, here we showcase a sustainable solution model for an endemic Himalayan medicinal herb, Trillium govanianum. The herb, being a rich source of diosgenin, is currently overharvested for its rhizome by extraction of the whole plant from the wild, leading to a drastic decline in its natural populations, and now declared Endangered. In the present study, we investigated whether there is an alternative sustainable source of diosgenin (i.e. leaves) other than rhizome in T. govanianum. We studied the spatial dynamics of diosgenin biosynthesis and accumulation using qRT-PCR-based targeted gene expression and High-Performance Liquid Chromatography-based diosgenin quantification in the leaf and rhizome samples of T. govanianum collected along the elevation gradients in Kashmir Himalaya. Our results revealed a higher diosgenin content in the leaf than in rhizome samples of T. govanianum. Expression analysis showed that, compared to the rhizome, the leaf samples exhibit relatively higher expression of all the seven genes of the diosgenin biosynthesis pathway. We also found a strong positive correlation between the expression of the targeted genes and diosgenin content in the leaf and rhizome samples. Overall, our findings offer a nature-based solution for the conservation and sustainable utilization of this imperiled endemic Himalayan herb, with lessons for elsewhere in the world.

The role of environmental gradients and microclimates in structuring communities and functional groups of lizards in a rainforest-savanna transition area.

Environmental heterogeneity poses a significant influence on the functional characteristics of species and communities at local scales. Environmental transition zones, such as at the savanna-forest borders, can act as regions of ecological tension when subjected to sharp variations in the microclimate. For ectothermic organisms, such as lizards, environmental temperatures directly influence physiological capabilities, and some species use different thermoregulation strategies that produce varied responses to local climatic conditions, which in turn affect species occurrence and community dynamics. In the context of global warming, these various strategies confer different types of vulnerability as well as risks of extinction. To assess the vulnerability of a species and understand the relationships between environmental variations, thermal tolerance of a species and community structure, lizard communities in forest-savanna transition areas of two national parks in the southwestern Amazon were sampled and their thermal functional traits were characterized. Then, we investigated how community structure and functional thermal variation were shaped by two environmental predictors (i.e., microclimates estimated locally and vegetation structure estimated from remote sensing). It was found that the community structure was more strongly predicted by the canopy surface reflectance values obtained via remote sensing than by microclimate variables. Environmental temperatures were not the most important factor affecting the occurrence of species, and the variations in ecothermal traits demonstrated a pattern within the taxonomic hierarchy at the family level. This pattern may indicate a tendency for evolutionary history to indirectly influence these functional features. Considering the estimates of the thermal tolerance range and warming tolerance, thermoconformer lizards are likely to be more vulnerable and at greater risk of extinction due to global warming than thermoregulators. The latter, more associated with open environments, seem to take advantage of their lower vulnerability and occur in both habitat types across the transition, potentially out-competing and further increasing the risk of extinction and vulnerability of forest-adapted thermoconformer lizards in these transitional areas.

Species diversity and extinction risk of vertebrate pollinators in India

AbstractAnimal pollinators underpin the functioning and persistence of ecosystems globally. However, the vital role of pollination is being progressively eroded by the worldwide decline of pollinator species caused by human-induced environmental degradation, resulting in rising costs to biodiversity, agriculture, and economy. Most studies quantifying pollinator diversity and declines have focused on insects, whereas vertebrate pollinators remain comparatively neglected. Here, we present the first comprehensive study quantifying the macroecological patterns of species richness and extinction risk of bird and mammal pollinators in India, a region of extremely high biodiversity and increasing anthropogenic pressure. Our results reveal that hotspots of mammal pollinator diversity are restricted to the south of the Western Ghats, whereas bird pollinator diversity hotspots are scattered throughout the country. Analyses of hotspots of threatened species (based on the IUCN Red List) show that only mammal pollinators are currently classified as threatened in India, whereas multiple hotspots of population declines were observed for birds, and primarily in the Southwest for mammal pollinators. Our analyses failed to identify a role for species traits as drivers of these patterns, whereas most pollinators appear to be threatened by agriculture, logging and hunting for food, and medicinal purposes. Pollinator endangerment has widescale ecological and economic implications such as reduced food production, plant extinction, loss of functional and genetic diversity, and economic damage. We suggest protection of vertebrate pollinators should be emphasised in active conservation agendas in India.

Climate and anthropogenic activities threaten two langur species irrespective of their range size

AbstractAimIf species fail to track the pace of climate change, areas of suitable habitat and population size are likely to decline, threatening species survivorship. Here, we incorporated multiple measures of environmental change and species‐specific habitat requirements to assess the responses of two closely related primate species to future changes in climate and habitat conversion. Specifically, we tested whether the comparatively wider‐ranging and Endangered François' langur (Trachypithecus francoisi) is better suited to withstand future anthropogenic habitat conversion and climate change than is the more narrowly ranging and critically endangered white‐headed langurs (T. leucocephalus).LocationChina.MethodsWe used species distribution models (SDMs) models and population viability analyses, and calculated dispersal velocity and biotic velocity, to predict the impact of climate and anthropogenic activity on the distribution and survivorship of two closely related primate species.ResultsWe found that: (1) by the year 2050, the area of suitable habitat for both primate species is expected to decline by 45% to 47%; (2) the population size of François' langurs is expected to increase to 4000 individuals (129%) and the population size of white‐headed langurs is expected to increase to 1400 individuals (133%); (3) biotic velocity, defined as the minimum migration rate required by a species to track its preferred climatic conditions, was 2.84 and 1.48 km/year for François' langurs and white‐headed langurs, respectively; and (4) dispersal velocity, defined as the distance a species has spread over a given period, was 0.82 km/year for both langur species.Main ConclusionsWe demonstrate that despite expected population growth, by the year 2050, habitat contraction and insufficient opportunities for dispersal will likely prevent both primate species from tracking and adjusting to changing climate conditions. Moreover, the more widely ranging species, T. francoisi, was not found to have a survival advantage over the more narrowly ranging species (T. leucocephalus) under future conditions of climate change and continued anthropogenic habitat conversion, resulting in a high risk of extinction for both langur species. The modelling approach used here is robust and can be successfully applied to other threatened animal taxa.

Evaluation of the diversity and genetic structure of Ceratozamia kuesteriana Regel. (Zamiaceae) in Tamaulipas, Mexico

AbstractGenetic diversity is the most widely used indicator to evaluate the evolutionary potential of a species. In theory, species with limited distribution are more susceptible to diversity loss. However, some species with restricted distribution occasionally present more diversity than expected, as is the case for some cycads. Ceratozamia kuesteriana is a microendemic species in El Cielo Biosphere Reserve in Tamaulipas, Mexico. Several previously reported populations have been eradicated in the last 10 years. The objective of this work was to estimate the levels of diversity and genetic structure in five populations within the reserve. The results show a high structure and differentiation, even when the populations are geographically proximal. However, overall diversity is high, with recent bottlenecks and alleles departing from neutrality, suggesting a broad, well‐adapted genetic base. Unfortunately, this genetic pool has recently become fragmented, posing a high extinction risk if allelic representativeness is absent in collections or botanical gardens.

Forensic genetics associated with hair analysis as a tool for jaguar (Panthera onca) identification

Animal smuggling and illegal wildlife trade comprise one of the most common crimes being committed on an international level. This action can affect biodiversity and most certainly increases the risk of extinction of several endangered species. Wildlife taxonomic identification is becoming routine to forensic experts. The aim of this study was to identify a possible jaguar sample (Panthera onca Linnaeus, 1958) from legal evidence using hair morphology and mitochondrial DNA (mtDNA) to help in an official animal identification. Scanning and optical microscope images of hair samples were used to compare diagnostic characteristics of felines to reference studies. A preserved region, (cytochrome oxidase subunit 1 (COI)), from mtDNA was sequenced and compared to a DNA database (GenBank) to perform genetic identification. Forensic genetic and hair analysis techniques combined positively identified the sample as jaguar. These methods can help practitioners and forensics experts to identify evidence collected in wildlife crimes suspected to involve jaguars.

Wildlife in the Tabuk Region, its Challenges and Protection Mechanisms, from the Islamic and Systemic Perspectives

Purpose: This research endeavors to safeguard the existence and reproductive capacities of beneficial wildlife organisms against the looming risks of extinction and extermination resulting from detrimental human actions. This endeavor is crucial for upholding environmental equilibrium, sequestering significant volumes of carbon emissions in the atmosphere, and mitigating the perils of swift climate changes. The study seeks to address a meticulously crafted set of inquiries, rooted in scientific and logical interpretation, aimed at devising viable and substantiated solutions. Key queries include rationale behind researching this specific topic, wildlife distribution within the Tabuk region, the efficacy of Islamic law mechanisms in averting and tackling these hazards, and the strategies employed by Saudi national environmental systems in safeguarding animal, plant, and aquatic wildlife.   Method: The research methodology involves an exhaustive examination of extant literature in environmental sciences, scrutinizing previous studies that delved into facets or components akin to the present research's domain. This approach contributes to augmenting the information reservoir concerning wildlife, its constituents, and functionalities. Furthermore, it addresses gaps discerned in prior research endeavors, thereby enhancing comprehension of the subject matter and obliterating ambiguities.   Implications of the research: By shedding light on the paramount issues and challenges imperiling wildlife organisms with extinction, the study underscores the imperative of implementing mechanisms outlined in Islamic law and Saudi national environmental systems. It strives to catalyze proactive measures for wildlife conservation, thereby fortifying ecological resilience and sustainability.   Originality/value: This research delineates a comprehensive analysis of wildlife conservation challenges and solutions, particularly within the purview of Islamic law and Saudi national environmental frameworks. It offers novel insights into mitigating threats posed to wildlife, augmenting existing knowledge, and furnishing recommendations to bolster conservation efforts.

Global mismatches between threat mapping research effort and the potential of threat abatement actions to reduce extinction risk.

Threat mapping is a necessary tool for identifying and abating direct threats to species in the ongoing extinction crisis. There are known gaps in the threat mapping literature for particular threats and geographic locations, and it remains unclear if the distribution of research effort is appropriately targeted relative to conservation need. We aimed to determine the drivers of threat mapping research effort and to quantify gaps that, if filled, could inform actions with the highest potential to reduce species' extinction risk. We used a negative binomial generalized linear model to analyze research effort as a function of threat abatement potential (quantified as the potential reduction in species extinction risk from abating threats), species richness, land area, and human pressure. The model showed that threat mapping research effort increased by 1.1 to 1.2 times per standardized unit change in threat abatement potential. However, species richness and land area were stronger predictors of research effort overall. The greatest areas of mismatch between research effort and threat abatement potential, receiving disproportionately low research effort, were related to the threats to species of agriculture, aquaculture, and biological resource use across the tropical regions of the Americas, Asia, and Madagascar. Conversely, the threat of linear infrastructure (e.g., roads and rails) across regions, the threat of biological resource use (e.g., hunting or collection) in sub-Saharan Africa, and overall threats in North America and Europe all received disproportionately high research effort. We discuss the range of methodological and sociopolitical factors that may be behind the overall trends and specific areas of mismatch we found. We urge a stronger emphasis on targeting research effort toward those threats and geographic locations where threat abatement activities could make the greatest contribution to reducing global species extinction risk.

Rising Temperatures, Falling Leaves: Predicting the Fate of Cyprus's Endemic Oak under Climate and Land Use Change.

Endemic island species face heightened extinction risk from climate-driven shifts, yet standard models often underestimate threat levels for those like Quercus alnifolia, an iconic Cypriot oak with pre-adaptations to aridity. Through species distribution modelling, we investigated the potential shifts in its distribution under future climate and land-use change scenarios. Our approach uniquely combines dispersal constraints, detailed soil characteristics, hydrological factors, and anticipated soil erosion data, offering a comprehensive assessment of environmental suitability. We quantified the species' sensitivity, exposure, and vulnerability to projected changes, conducting a preliminary IUCN extinction risk assessment according to Criteria A and B. Our projections uniformly predict range reductions, with a median decrease of 67.8% by the 2070s under the most extreme scenarios. Additionally, our research indicates Quercus alnifolia's resilience to diverse erosion conditions and preference for relatively dry climates within a specific annual temperature range. The preliminary IUCN risk assessment designates Quercus alnifolia as Critically Endangered in the future, highlighting the need for focused conservation efforts. Climate and land-use changes are critical threats to the species' survival, emphasising the importance of comprehensive modelling techniques and the urgent requirement for dedicated conservation measures to safeguard this iconic species.

A novel data-driven reduced order modelling methodology for simulation of humid blowout in wet combustion applications

Computationally inexpensive reduced order models such as Chemical Reactor Networks (CRN) are encouraging tools to obtain fast numerical solutions. However, the accuracy of such models is usually compromised compared to experiments or high-fidelity numerical simulations. Therefore, continued improvement of such models is necessary to ensure reasonable accuracy and fill the need for computationally inexpensive tools. To that end, inputs from computational fluid dynamics simulations have been used to build CRNs in the last 25 years. This can be further improved by the application of data-driven techniques. The present work uses a novel data-driven analysis based on high-fidelity simulation results where the high-dimensional data is first reduced to a low-dimensional manifold and is then clustered into chemically coherent regions. These results along with the high-fidelity simulation results are used to construct a CRN for wet combustion simulations. Wet combustion is a novel clean combustion technique, where an increase in the level of steam dilution distributes the flame, with a risk for flame extinction. This phenomenon, i.e., humid blowout (HBO), was modelled using the above-mentioned CRN. The HBO predicted by the CRN was also tested for thermal power, equivalence ratio, and fuel conditions different from its design point. The error in HBO prediction was quantified by comparing the steam-dilution level at HBO obtained using CRN and that obtained experimentally. The CRN predicted the HBO with an error magnitude less than 5% when the thermal power was unchanged. The maximum error in all tested conditions was 16.65%. Furthermore, a sensitivity analysis revealed that the inclusion of hot gas recirculation through the central recirculation zone, quantified by the mass flow split between the post-flame region and the CRZ, is important in the prediction of HBO, although its accuracy is inconsequential.

Does mutual interference stabilize prey–predator model with Bazykin–Crowley–Martin trophic function?

We investigated a system of ordinary differential equations that describes the dynamics of prey and predator populations, taking into account the Allee effect affecting the reproduction of the predator population, and mutual interference amongst predators, which is modeled with the Bazykin–Crowley–Martin (BCM) trophic function. Bifurcation analysis revealed a rich spectrum of bifurcations occurring in the system. In particular, analytical conditions for the saddle–node, Hopf, cusp, and Bogdanov–Takens bifurcations were derived for the model parameters, quantifying the strength of the predator interference, the Allee effect, and the predation efficiency. Numerical simulations verify and illustrate the analytical findings. The main purpose of the study was to test whether the mutual interference in the model with BCM trophic function provides a stabilizing or destabilizing effect on the system dynamics. The obtained results suggest that the model demonstrates qualitatively the same pattern concerning varying the interference strength as other predator-dependent models: both low and very high interference levels increase the risk of predator extinction, while moderate interference has a favorable effect on the stability and resilience of the prey–predator system.

Genetic insights into Cyphocharax magdalenae (Characiformes: Curimatidae): Microsatellite loci development and population analysis in the Cauca River, Colombia.

Cyphocharax magdalenae, a Colombian freshwater fish species, plays a vital role in nutrients distribution and serves as a significant food source for other fish species and local fishing communities. Considered a short-distance migratory species, C. magdalenae populations face substantial extinction risk due to human activities impacting their habitats. To address the lack of knowledge on genetic diversity and population structure, this study used next-generation sequencing technology to develop species-specific microsatellite loci and conducted a population genetics analysis of C. magdalenae in the middle and lower sections of the Cauca River, Colombia. Out of 30 pairs of microsatellite primers evaluated in 324 individuals, 14 loci were found to be polymorphic, at linkage equilibrium and, in at least one population, their genotypic frequencies were in Hardy-Weinberg equilibrium. Results showed high genetic diversity levels compared to other neotropical Characiformes, with inbreeding coefficients similar to those reported for phylogenetically related species. Moreover, C. magdalenae exhibits seasonal population structure (rainy-dry) consisting of two genetic stocks showing bottleneck signals and high effective population sizes. This information is essential for understanding the current species genetics and developing future management programs for this fishery resource.

Clinging to the top: natal dispersal tracks climate gradient in a trailing-edge population of a migratory songbird.

Trailing-edge populations at the low-latitude, receding edge of a shifting range face high extinction risk from climate change unless they are able to track optimal environmental conditions through dispersal. We fit dispersal models to the locations of 3165 individually-marked black-throated blue warblers (Setophaga caerulescens) in the southern Appalachian Mountains in North Carolina, USA from 2002 to 2023. Black-throated blue warbler breeding abundance in this population has remained relatively stable at colder and wetter areas at higher elevations but has declined at warmer and drier areas at lower elevations. Median dispersal distance of young warblers was 917m (range 23-3200m), and dispersal tended to be directed away from warm and dry locations. In contrast, adults exhibited strong site fidelity between breeding seasons and rarely dispersed more than 100m (range 10-1300m). Consequently, adult dispersal kernels were much more compact and symmetric than natal dispersal kernels, suggesting adult dispersal is unlikely a driving force of declines in this population. Our findings suggest that directional natal dispersal may mitigate fitness costs for trailing-edge populations by allowing individuals to track changing climate and avoid warming conditions at warm-edge range boundaries.

Implications of Climate-Induced Localised Extinction of Bull Kelp (Durvillaea amatheiae) for Holdfast Macrofauna

Globally, work is being undertaken to preserve biodiversity and prevent further species extinctions. Yet, without adequate data about the presence of species within ecosystems, hidden extinctions can occur without our knowledge. Given that poleward range retractions are projected for bull kelp (Durvillaea amatheiae) in southeastern Australia, there is the potential for hidden extinctions to occur in associated macrofaunal species. However, this risk cannot be assessed due to the limited data on the invertebrate macrofauna associated with D. amatheiae. We documented macrofauna within D. amatheiae holdfasts, with the objective of establishing a first analysis of the holdfast fauna for this kelp and identifying, where possible, any host-specific taxa. Holdfasts were collected at six locations, spanning most of the range of D. amatheiae on the southeastern Australian mainland. Macrofauna were removed from holdfasts and identified to the lowest possible taxonomic level. Modelling was applied to determine factors correlated with patterns of assemblages among locations. Holdfast assemblages were found to vary significantly among locations and exhibited a latitudinal gradient in assemblage structure. The northernmost location (Aragunnu), which has the highest risk of D. amatheiae range retractions, was found to have distinct species assemblages and generally higher diversity and abundance than locations further south. However, no host-specific taxa were identified in samples, indicating that there is a low risk of multiple hidden species extinctions occurring in holdfast macrofauna, due to future range retractions of D. amatheiae. Rather, most of the macrofauna taxa in D. amatheiae holdfasts were found to also occur in association with the sympatric golden kelp Ecklonia radiata, which is not expected to undergo range retractions at the latitudes where losses of D. amatheiae are projected. Overall, there is an urgent need to develop strategies to combat projected future range retractions of D. amatheiae to reduce impacts on the species that rely on D. amatheiae for habitat.

Genomic insights into local adaptation and vulnerability of Quercus longinux to climate change

BackgroundClimate change is expected to alter the factors that drive changes in adaptive variation. This is especially true for species with long life spans and limited dispersal capabilities. Rapid climate changes may disrupt the migration of beneficial genetic variations, making it challenging for them to keep up with changing environments. Understanding adaptive genetic variations in tree species is crucial for conservation and effective forest management. Our study used landscape genomic analyses and phenotypic traits from a thorough sampling across the entire range of Quercus longinux, an oak species native to Taiwan, to investigate the signals of adaptation within this species.ResultsUsing ecological data, phenotypic traits, and 1,933 single-nucleotide polymorphisms (SNPs) from 205 individuals, we classified three genetic groups, which were also phenotypically and ecologically divergent. Thirty-five genes related to drought and freeze resistance displayed signatures of natural selection. The adaptive variation was driven by diverse environmental pressures such as low spring precipitation, low annual temperature, and soil grid sizes. Using linear-regression-based methods, we identified isolation by environment (IBE) as the optimal model for adaptive SNPs. Redundancy analysis (RDA) further revealed a substantial joint influence of demography, geology, and environments, suggesting a covariation between environmental gradients and colonization history. Lastly, we utilized adaptive signals to estimate the genetic offset for each individual under diverse climate change scenarios. The required genetic changes and migration distance are larger in severe climates. Our prediction also reveals potential threats to edge populations in northern and southeastern Taiwan due to escalating temperatures and precipitation reallocation.ConclusionsWe demonstrate the intricate influence of ecological heterogeneity on genetic and phenotypic adaptation of an oak species. The adaptation is also driven by some rarely studied environmental factors, including wind speed and soil features. Furthermore, the genetic offset analysis predicted that the edge populations of Q. longinux in lower elevations might face higher risks of local extinctions under climate change.