High Risk Of Extinction Research Articles

Coleus hakgalensis (Lamiaceae), a new species from Sri Lanka

Coleus hakgalensis, a new species in family Lamiaceae, is described from the central highlands of Sri Lanka. The dry specimens of the new species are morphologically similar to Coleus paniculatus specimens but distinguishable by its much branched habit with arcuate branches, stem up to 1m in height, elongated inflorescence, bracts being occasionally persistent and shortly petiolated, having hairs inside the upper lip of calyx, semi-circular lateral lobes of upper lip of corolla being much shorter than median lobes, navicular lower lip of corolla with densely pilose inside, stamens united at base and anterior projection of the disc equal or shorter than ovary with an acute apex. The new species is under high risk of extinction in the wild thus ex-situ conservation measures have been implemented.

Stable detection frequency of the threatened Christmas Island Boobook Ninox natalis, 2012–2022

ABSTRACT Both island species and raptors are at particularly high risk of extinction but few island raptor populations have been the subject of long-term monitoring. To determine trends in abundance in the Christmas Island Boobook, surveys were conducted annually from 2012–2017, in 2019 and in 2022. Across the survey period the population appears to have been either stable or to have increased slightly. Almost no part of the island lacked owls during the most recent survey. The detection rate averaged 1.56 (out of four surveys at a site); it was lowest in 2013 (1.22) and highest in 2022 (2.38). Detection was more likely on nights with low wind, at wetter sites and in closed vegetation, rather than in open or very low vegetation. In a separate analysis on the same data, the top-ranked dynamic occupancy-detection model found that occupancy increased with increasing elevation and vegetation height. No effect of a suspected threat, the presence of invasive yellow crazy ants Anoplolepis gracilipes at a site, could be detected. We recommend ongoing monitoring and research, potentially using automated recording devices and the tracking of individual owls to understand and refine the assumptions underpinning the interpretation of survey results.

Habitat Fragmentation Affects Richness—A View Through a Metacommunity Lens

Habitat fragmentation is often assumed to negatively impact species diversity because smaller, more isolated populations on smaller habitat patches are at a higher extinction risk. However, some empirical and theoretical studies suggest that landscapes with numerous small habitat patches may support higher species richness, although the circumstances remain elusive. We used an agent-based metacommunity model to investigate this and simulate landscapes of the same total area but diverse patch sizes. Our model, as generic and unbiased by specific assumptions as possible, aimed to explore which circumstances may be more conducive to supporting higher biodiversity. To this end, most parameters and behaviors were random. The model included generalized species traits, dispersal, and interactions to explore species richness dynamics in fragmented landscapes of distinct patch sizes. Our results show that landscapes with many small patches maintain higher species richness than those with fewer large patches. Moreover, the relationship between patch connectivity and species richness is more pronounced in landscapes with smaller patches. High connectivity in these landscapes may support species diversity by preventing local extinctions and facilitating recolonization. In contrast, connectivity is less significant in large-patch landscapes, where generalist species dominate. The findings highlight the complex interplay between patch size quality, connectivity, species traits, and diverse interactions among species in determining species richness. We suggest the patterns produced by the model represent null predictions and may be useful as a reference for a diversity of more specialized questions and predictions. These insights may also have specific implications for conservation strategies, suggesting that maintaining a mosaic of small, well-connected patches could enhance biodiversity in fragmented landscapes.

Conservation priorities for functionally unique and specialized terrestrial vertebrates threatened by biological invasions.

Invasive non-native species (INS) continue to pose a significant threat to biodiversity, including native population declines, which can ultimately disrupt ecosystem processes. Although there is growing evidence of the impacts of INS on functional diversity, most of the existing approaches to prioritization of species for conservation still focus on taxonomic diversity, neglecting the ecological role of species. We developed the functionally unique, specialized, and endangered by invasive non-native species (FUSE INS) score to fill this gap by combining functional irreplaceability (i.e., uniqueness and specialization) of species with their extinction risk due to INS. We calculated this score for 3642 terrestrial vertebrates exposed to INS by assessing how INS affected them based on the IUCN Red List and by evaluating their specialization and uniqueness in a multidimensional functional space. Thirty-eight percent of native species were both at high extinction risk because of INS and functionally unique and specialized, making them priority species for INS impact mitigation. Priority species of amphibians concentrated in Central America and Madagascar and of lizards in the Caribbean islands, northern Australia, New Zealand, and New Caledonia. Priority bird and mammal species were more widespread (birds, mostly in coastal areas, on Pacific islands, and in northern India and New Zealand; mammals, in southwestern Europe, Central Africa, East Africa, Southern Africa, Southeast Asia, and eastern Australia). Seventy-eight species were also highly irreplaceable but not yet threatened by INS, suggesting that preventive conservation measures may help protect these species. For the 50 birds of the highest priority, 64% required conservation actions to mitigate the INS threat. The FUSE INS score can be used to help prioritize indigenous species representing large amounts of functional diversity. Incorporating functional diversity into the conservation prioritization of species and associated areas is key to accurately reducing and mitigating the impacts of INS on native biodiversity.

The state of the bats in North America.

The world's rich diversity of bats supports healthy ecosystems and important ecosystem services. Maintaining healthy biological systems requires prompt identification of threats to biodiversity and immediate action to protect species, which for wide-ranging bat species that span geopolitical boundaries warrants international coordination. Anthropogenic forces drive the threats to bats throughout North America and the world. We conducted an international expert elicitation to assess the status of 153 bat species in Canada, the United States, and Mexico. We used expert assessment to determine the conservation status, highest impact threats, and recent population trends for these species. We found that 53% of North American bat species have moderate to very high risk of extinction in the next 15 years. The highest impact threats varied with species and country, and four IUCN threat categories had the greatest overall impacts: Climate Change, Problematic Species (including disease), Agriculture, and Energy Production. Experts estimated that 90% of species assessed had decreasing population trends over the past 15 years, demonstrating the need for conservation action. Although the state of North American bats is concerning, we identify threats that can be addressed through internationally collaborative, proactive, and protective actions to support the recovery and resilience of North American bat species.

Population isolation in the Plains spadefoot toad: causes and conservation implications.

Range disjunctions appear to be common in nature, although they may be caused by various factors. They may simply be an artefact of inadequate sampling. If real, they may be the result of colonization events or habitat change. With natural habitats showing increasing fragmentation because of human activity, understanding the cause of a disjunction can have important conservation implications. We investigate the geographical range of the Plains spadefoot toad, Spea bombifrons, a widely distributed species in the midwestern and southwestern United States, with a putative disjunct population in southern Texas. We combine GIS mapping, species distribution modeling, and population genetic analysis to investigate this putative disjunction. We establish that this southern Texas population is truly geographically disjunct and genetically distinct. Further, using climate projections we show that this unique population is at high risk of local extinction.

The role of protected areas in the Balkan freshwater biodiversity conservation: The case of Blidinje Nature Park (Southwestern Bosnia-Herzegovina)

Freshwaters of the Balkan Peninsula show high levels of endemism and relict species, which are still little studied and are threatened by numerous anthropogenic stressors. Protected areas could give special opportunities to improve knowledge of their biodiversity and develop proper conservation measures for the most at-extinction risk species. The aims of this research were to: i) fill the knowledge gap regarding fish and crustaceans occurring in the main water bodies of the Blidinje Nature Park (Southwestern Bosnia-Herzegovina); ii) assess the population abundance and growth, for the species of conservational interest; iii) identify fish biodiversity hotspots in Bosnia-Herzegovina; iv) identify anthropogenic pressures and suggest proper conservation measures. Fish and crayfish data were collected in four sampling sites located on the main water bodies, using electrofishing and gillnets, in three sampling phases over the period July 2022-August 2023. The presence of three species at high extinction risk has been detected: Squalius tenellus, Aulopyge huegelii and Astacus astacus. Their populations were abundant, with balanced age structure and good growth performance. A spatial analysis allowed to quantify the fractions of the endemic species range covered by the Blidinje Nature Park, which were 6.1% and 2.3% for S. tenellus and A. huegelii, respectively. The presence of invasive Atlantic trout and overharvesting of crayfish seem to represent the main anthropogenic pressures on freshwater biota. The obtained information allowed to expand the knowledge on the distribution and population status of threatened species and to highlight diversity hotspots as valuable tools for their conservation and management.

Verifying the Diet of the Slender Racer, <i>Orientocoluber spinalis</i> (Peters, 1866), Rare, Threatened, and Endangered Across Northeast Asian Countries

Understanding the diet of a species provides important information on various aspects of its ecology. Diet studies are few on the reptile species, of which observation frequency is very low, due to the great difficulty of sampling. We investigated the diet of Orientocoluber spinalis, a long and slender small grassland snake with high rarity and a high extinction risk across northeast Asian countries, by applying regurgitated stomach content analysis and metabarcoding analysis using a developed O. spinalis blocking primer. Among 19 diet samples, which were mainly collected on islands along the west coast of the Korean Peninsula, we determined the food sources of 13 samples, which consisted of four small vertebrate species, the Tsushima smooth skink (Scincella vandenburghi), mountain grass lizard (Takydromus wolteri), Japanese keelback (Hebius vibakari), and lesser white-toothed shrew (Crocidura shantungensis). Among them, O. spinalis most frequently fed on S. vandenburghi (10 of 13 cases). Our results show that O. spinalis mainly forages small reptiles and mammals in grasslands adjoining to lowland forests and could be beneficial for conservation in the field and rearing of this vulnerable species in the facilities.

High extinction risk in large foraminifera during past and future mass extinctions.

There is a strong relationship between metazoan body size and extinction risk. However, the size selectivity and underlying mechanisms in foraminifera, a common marine protozoa, remain controversial. Here, we found that foraminifera exhibit size-dependent extinction selectivity, favoring larger groups (>7.4 log10 cubic micrometer) over smaller ones. Foraminifera showed significant size selectivity in the Guadalupian-Lopingian, Permian-Triassic, and Cretaceous-Paleogene extinctions where the proportion of large genera exceeded 50%. Conversely, in extinctions where the proportion of large genera was <45%, foraminifera displayed no selectivity. As most of these extinctions coincided with oceanic anoxic events, we conducted simulations to assess the effects of ocean deoxygenation on foraminifera. Our results indicate that under suboxic conditions, oxygen fails to diffuse into the cell center of large foraminifera. Consequently, we propose a hypothesis to explain size distribution-related selectivity and Lilliput effect in animals relying on diffusion for oxygen during past and future ocean deoxygenation, i.e., oxygen diffusion distance in body.

Species richness, composition, distribution and conservation status of herpetofauna in a global hotspot: The Mountains of Southwest China

Herpetofauna have attracted considerable global attention due to their high risk of extinction. The Mountains of Southwest China are among the 36 global biodiversity hotspots due to their high biodiversity and irreplaceability, and the Shaluli Mountains are the core area of this region. However, the diversity and conservation status of herpetofauna in the Shaluli Mountains remain unclear. In this study, we updated the species richness and composition information of herpetofauna in the Shaluli Mountains based on extensive field expeditions, published literature, and museum specimens. In addition, we identified the local hotspots and key environmental factors limiting species distribution using environmental niche models (ENMs). Furthermore, we evaluated the conservation status of the key species via the Red List Index and gap analysis. Our results revealed a total of 68 herpetofauna species, representing 30 amphibians (21 genera in nine families) and 38 reptiles (19 genera in six families). The amphibian richness showed a hump-shaped pattern along the elevational gradient, while the reptile richness showed a monotonically decreasing pattern. The dry-hot river valley was identified as a local hotspot, and the key environmental factors limiting the richness of herpetofauna species differed. Moreover, the regional Red List indices for amphibians and reptiles were 0.87 and 0.8, respectively, showing that the overall threat level of this region was low. However, there are large conservation gaps in the protection of key species. Our study indicated that new protected areas should be established and the existing protected areas should be upgraded to protect herpetofauna with a large conservation gap.

Low human interest for the most at-risk reef fishes worldwide.

Human interest in biodiversity is essential for effective conservation action but remains poorly quantified at large scales. Here, we investigated human interest for 2408 marine reef fishes using data obtained from online public databases and social media, summarized in two synthetic dimensions, research effort and public attention. Both dimensions are mainly related to geographic range size. Research effort is also linked to fishery importance, while public attention is more related to fish aesthetic value and aquarium trade importance. We also found a strong phylogenetic bias, with certain fish families receiving disproportional research effort and public attention. Most concerningly, species at the highest risk of extinction and those most vulnerable to future climate change tend to receive less research effort and public attention. Our results provide a lens through which examining the societal attention that species garner, with the ultimate goals to improve conservation strategies, research programs, and communication plans.

Conservation status of sharks and rays caught in Indonesian Fisheries Management Area 712

Abstract. Lelono TD, Bintoro G, Setyanto A, Setyahadi D, Sutjipto DO, Adhihapsari W, Aliviyanti D, Isdianto A. 2024. Conservation status of sharks and rays caught in Indonesian Fisheries Management Area 712. Biodiversitas 25: 2603-2614. Elasmobranchs, including sharks and rays, are some of the most vulnerable marine fish and are particularly at risk from fishing pressure. Sharks and rays landing data that listed in the Convention on International Trade in Endangered Species (CITES) appendices and/or assessed as in The International Union for Conservation of Nature (IUCN) Red List threatened categories were collected from July to October 2023 at two sites in Indonesian Fisheries Management Area (FMA) 712, East Java, Indonesia, namely Pelabuhan Perikanan Nusantara (PPN) Brondong at Lamongan District and Pelabuhan Perikanan Pantai (PPP) Muncar at Banyuwangi. Stingray species designated as Critically Endangered (CR), Endangered (EN), or Vulnerable (VU) were recorded at both landing sites. More IUCN Red List threatened ray species were recorded at Brondong than at Muncar. Based on Brondong's international trade status, ray species landed at Brondong are at higher risk of extinction than those landed at PPP Muncar. Six shark species are currently listed in CITES Appendix II: A pelagicus, A. superciliosus, S. lewini, S. zygaena, C. falciformis, and I. oxyrinchus. At PPP Muncar, two of these species were traded. Sharks landing at Muncar included species in IUCN Red List categories, while those landing at Brondong were in four categories. Two CITES categories regulate the capture of sharks landed at PPP Muncar and PPN Brondong. At both sites, numerous species with conservation statuses of CR, EN, VU, and NT are still caught. In conclusion, exploitation and insufficient control threaten the shark and ray populations in PPP Muncar and PPN Brondong. To save these species, conservation efforts should prioritize trade monitoring, habitat protection, and stricter laws.

Diverse Circular DNA Viral Communities in Blood, Oral, and Fecal Samples of Captive Lemurs.

Few studies have addressed viral diversity in lemurs despite their unique evolutionary history on the island of Madagascar and high risk of extinction. Further, while a large number of studies on animal viromes focus on fecal samples, understanding viral diversity across multiple sample types and seasons can reveal complex viral community structures within and across species. Groups of captive lemurs at the Duke Lemur Center (Durham, NC, USA), a conservation and research center, provide an opportunity to build foundational knowledge on lemur-associated viromes. We sampled individuals from seven lemur species, i.e., collared lemur (Eulemur collaris), crowned lemur (Eulemur coronatus), blue-eyed black lemur (Eulemur flavifrons), ring-tailed lemur (Lemur catta), Coquerel's sifaka (Propithecus coquereli), black-and-white ruffed lemur (Varecia variegata variegata), and red ruffed lemur (Varecia rubra), across two lemur families (Lemuridae, Indriidae). Fecal, blood, and saliva samples were collected from Coquerel's sifaka and black-and-white ruffed lemur individuals across two sampling seasons to diversify virome biogeography and temporal sampling. Using viral metagenomic workflows, the complete genomes of anelloviruses (n = 4), cressdnaviruses (n = 47), caudoviruses (n = 15), inoviruses (n = 34), and microviruses (n = 537) were determined from lemur blood, feces, and saliva. Many virus genomes, especially bacteriophages, identified in this study were present across multiple lemur species. Overall, the work presented here uses a viral metagenomics approach to investigate viral communities inhabiting the blood, oral cavity, and feces of healthy captive lemurs.

Future trends of marine fish biomass distributions from the North Sea to the Barents Sea

Climate warming is one of the facets of anthropogenic global change predicted to increase in the future, its magnitude depending on present-day decisions. The north Atlantic and Arctic Oceans are already undergoing community changes, with warmer-water species expanding northwards, and colder-water species retracting. However, the future extent and implications of these shifts remain unclear. Here, we fitted a joint species distribution model to occurrence data of 107, and biomass data of 61 marine fish species from 16,345 fishery independent trawls sampled between 2004 and 2022 in the northeast Atlantic Ocean, including the Barents Sea. We project overall increases in richness and declines in relative dominance in the community, and generalised increases in species’ ranges and biomass across three different future scenarios in 2050 and 2100. The projected decline of capelin and the practical extirpation of polar cod from the system, the two most abundant species in the Barents Sea, drove an overall reduction in fish biomass at Arctic latitudes that is not replaced by expanding species. Furthermore, our projections suggest that Arctic demersal fish will be at high risk of extinction by the end of the century if no climate refugia is available at eastern latitudes.

Conservation genomics of the critically endangered Chinese pangolin.

The Chinese pangolin (Manis pentadactyla, MP) has been extensively exploited and is now on the brink of extinction, but its population structure, evolutionary history, and adaptive potential are unclear. Here, we analyzed 94 genomes from three subspecies of the Chinese pangolin and identified three distinct genetic clusters (MPA, MPB, and MPC), with MPB further divided into MPB1 and MPB2 subpopulations. The divergence of these populations was driven by past climate change. For MPB2 and MPC, recent human activities have caused dramatic population decline and small population size as well as increased inbreeding, but not decrease in genomic variation and increase in genetic load probably due to strong gene flow; therefore, it is crucial to strengthen in situ habitat management for these two populations. By contrast, although human activities have a milder impact on MPA, it is at high risk of extinction due to long-term contraction and isolation, and genetic rescue is urgently needed. MPB1 exhibited a relatively healthy population status and can potentially serve as a source population. Overall, our findings provide novel insights into the conservation of the Chinese pangolin and biogeography of the mammals of eastern Asia.

Ecological genetics of isolated loach populations indicate compromised adaptive potential

Many endangered species live in fragmented and isolated populations with low genetic variability, signs of inbreeding, and small effective population sizes - all features elevating their extinction risk. The flat-headed loach (Oreonectes platycephalus), a small noemacheilid fish, is widely across southern China, but only in the headwaters of hillstreams; as a result, they are spatially isolated from conspecific populations. We surveyed single nucleotide polymorphisms in 16 Hong Kong populations of O. platycephalus to determine whether loach populations from different streams were genetically isolated from each other, showed low levels of genetic diversity, signs of inbreeding, and had small contemporary effective population sizes. Estimates of average observed heterozygosity (HO = 0.0473), average weighted nucleotide diversity (πw = 0.0546) and contemporary effective population sizes (Ne = 10.2 ~ 129.8) were very low, and several populations showed clear signs of inbreeding as judged from relatedness estimates. The degree of genetic differentiation among populations was very high (average FST = 0.668), even over short geographic distances (<1.5 km), with clear patterns of isolation by distance. These results suggest that Hong Kong populations of O. platycephalus have experienced strong genetic drift and loss of genetic variability because sea-level rise after the last glaciation reduced connectedness among paleodrainages, isolating populations in headwaters. All this, together with the fact that the levels of genetic diversity and contemporary effective population sizes within O. platycephalus populations are lower than most other freshwater fishes, suggests that they face high local extinction risk and have limited capacity for future adaptation.

The complete female mitogenome of Potomida semirugata (Lamarck, 1819)

Freshwater mussels perform important ecological functions in ecosystems, such as water filtration and energy cycling. Unlike marine bivalves, freshwater mussels have unique characteristics including internal fertilization and parental care. Some freshwater mussels are facing a high risk of extinction due to several factors such as climate change and habitat loss. Potomida semirugata (Lamarck, 1819) is one of the freshwater mussel species with a high risk of extinction and listed as Endangered in the Red List of the International Union for Conservation of Nature. Here, we present the first F-type mitogenome sequence of P. semirugata. The genome was sequenced on an Illumina high-throughput platform from a P. semirugata specimen collected from the Tersakan River (Turkey). The 16,093 bp mitochondrial genome sequence contains 13 protein-coding genes, 22 transfer RNAs, and two ribosomal RNAs. Phylogenetic analysis placed P. semirugata in the Lamprotulini clade with Potomida littoralis, as expected. Potomida semirugata is a poorly studied species and the genomic resource provided here will contribute to a better understanding of its biological characterization.

Evaluating sustainability of Thalictrum petaloideum L., a peripheral population in Korea

Conservation of rare plants, both at the national level and the regional level is important to maintain and conserve plant diversity. This study focused on Thalictrum petaloideum L., an endangered species, for which the Korean peninsula represents the rear edge of the global distribution. T. petaloideum is distributed in isolated populations across four regions. Yeongwol, in Gangwon, had the largest extent of distribution (27,663 m2), the highest number of sub-populations (204), and the highest total population size (87,681), followed by Danyang, in Chungbuk (3970 m2/28/10,285), Samcheok, in Gangwon (3390 m2/13/3871), and Yeosu, in Jeolanam (800 m2/10/816), in descending order. The most stable population structure was found in Yeongwol. Yeosu was found to have the most unstable population structure and the highest risk of extinction. To ensure the sustainability of the population in Yeosu, artificial management of climbing plants, such as Pueraria lobata, is recommended to maintain spaces suitable for regeneration. In Yeongwol, the population is likely to be sustained over a long period. The maintenance of traditional graveyards is necessary to ensure the population’s sustainability. Further studies should assess the genetic characteristics of each regional population for an in-depth characterization of plant distribution on the Korean peninsula.

Population genomics of the endangered freshwater mussel, Arcidens wheeleri (Unionoidea: Unionidae: Anodontini), in the Little River, Arkansas, USA

ABSTRACT North America is a hotspot of freshwater mussel diversity. However, over the last century, many anthropogenic stressors have led to substantial declines in freshwater mussels of the families Unionidae and Margaritiferidae in North America. Conserving the remaining mussel fauna is a priority, as they play an integral role in freshwater ecosystems. The Little River in Arkansas is home to one of the last remaining populations of the federally endangered freshwater mussel, Arcidens wheeleri (Unionidae: Anodontini). Population dynamics information is lacking for A. wheeleri, and no population genetics study has been conducted on this species. A greater understanding of the genetic diversity within a population can serve as a benchmark for developing an effective management plan. We sampled A. wheeleri from three locations in the Little River. Genomic data were generated with a single-enzyme restriction-site-associated DNA sequencing approach to assess genetic diversity and structure of A. wheeleri in the Little River. Genetic structure analyses indicated one genetic population among the three locations, with limited, fine-scale subpopulation structure. Observed heterozygosity values were considerably lower than expected heterozygosity values, with Ho = 0.14 and He = 0.22, likely indicating a genetic bottleneck. Demographic analysis of the Little River population of A. wheeleri also suggests a historical bottleneck. Furthermore, a high inbreeding coefficient (FIS = 0.33) indicates A. wheeleri in the Little River is losing genetic diversity. Data generated indicate considerable risk of extirpation for A. wheeleri from the Little River and should serve as a baseline for future monitoring. Given its high risk of extinction, we recommend increased study of A. wheeleri across its range and on-the-ground conservation actions that include habitat protection and restoration, which are the only options until a successful host fish and protocols are identified for propagation.

Assessing the extinction risk of the spontaneous flora in urban tree bases.

As the spatial arrangement of trees planted along streets in cities makes their bases potential ecological corridors for the flora, urban tree bases may be a key contributor to the overall connectivity of the urban ecosystem. However, these tree bases are also a highly fragmented environment in which extinctions are frequent. The goal of this study was to assess the plant species' ability to survive and spread through urban tree bases. To do so, we developed a Bayesian framework to assess the extinction risk of a plant metapopulation using presence/absence data, assuming that the occupancy dynamics was described by a Hidden Markov Model. The novelty of our approach is to take into account the combined effect of low-distance dispersal and the potential presence of a seed bank on the extinction risk. We introduced a metric of the extinction risk and examined its performance over a wide range of metapopulation parameters. We applied our framework to yearly floristic inventories carried out in 1324 tree bases in Paris, France. While local extinction risks were generally high, extinction risks at the street scale varied greatly from one species to another. We identified 10 plant species that could survive and spread through urban tree bases, and three plant traits correlated with the extinction risk at the metapopulation scale: the maximal height, and the beginning and end of the flowering period. Our results suggest that some plant species can use urban tree bases as ecological corridors despite high local extinction risks by forming a seed bank. We also identified other plant traits correlated with the ability to survive in tree bases, related to the action of gardeners. Moreover, our findings demonstrate that our Bayesian estimation framework based on percolation theory has the potential to be extended to more general metapopulations.