Understudied Species Research Articles

Intrapopulation karyotypic and cranial characterization of Blarinomys breviceps (Rodentia: Sigmodontinae) from Minas Gerais, Brazil

Despite its wide geographical distribution and habit specialization, Blarinomys breviceps is an understudied species. In this work, we analyzed for the first time the intrapopulation variation of the karyotype and cranial measurements of specimens collected in Minas Gerais state, Brazil. We described three new karyotypes with different diploid numbers due to the presence of B chromosomes (2n = 40, 2n = 41, and 2n = 42, with FN = 50), using conventional staining, GTG- and CBG-banding, Ag-NOR, and FISH with a telomeric probe. In addition, morphometric analyses based on twenty-two quantitative cranial characters showed absence of sexual dimorphism contributing to future studies of geographic variation of the species.

Thermoregulatory Strategies of Diving Air-Breathing Marine Vertebrates: A Review

The aquatic habitat of marine “air-breathing” vertebrates provides a significant thermoregulatory challenge due to the high thermal conductivity of water. In addition to temperature changes across their range, air-breathing vertebrates experience temperature changes on the timescale of seconds to minutes as they perform dives to access two critical resources: air at the surface and food at depth. In response to these challenges, air-breathing vertebrates have developed morphological and physiological adaptations that align with their life histories and phylogenies and contribute to homeostasis. However, the physiological and behavioral mechanisms used to maintain thermal balance while diving is still poorly understood. The cardiovascular system is integral to the physiological responses associated with the dive response, exercise, digestion, and thermoregulation. The adjustments required to meet one physiological demand may not be compatible with another and can result in a potential conflict between the various physiological demands imposed on air-breathing divers. We reviewed the literature on thermoregulation while diving in an effort to synthesize our current understanding of the thermoregulatory strategies of diving air-breathing marine vertebrates. Studies have demonstrated that thermoregulatory strategies can involve the temporal separation of two conflicting responses, a compromise in the performance of one response over another, or coordination of synergistic responses. We hope that a review and synthesis of both laboratory and field studies will stimulate future research efforts at the intersection of thermoregulation and diving physiology. Expanding the use of physiological biologgers, particularly to understudied species, will enhance our understanding of how these animals coordinate various physiological demands to maintain homeostasis in a thermally challenging environment.

Identification of bioactive compounds from Rhaponticoides iconiensis extracts and their bioactivities: An endemic plant to Turkey flora

Rhaponticoides iconiensis (Hub.-Mor.) M.V.Agab. & Greuter. (Asteraceae) is an endemic species spread in several small populations in the province of Konya (Turkey). It is critically endangered with an extremely high risk of extinction. Recently, based on the molecular phylogenetic and eco geographical studies on Cardueae-Centaureinae, the genus Rhaponticoides Vaill. was separated from Centaurea L. Antioxidant properties and enzyme inhibition, as well as the phenolic and flavonoid contents, of the methanol (Soxhlet extraction and maceration) and water (infusion) extracts of R. iconiensis leaves, roots, and flower heads were determined. The methanol extracts of R. iconiensis leaves contained the highest amount of phenolic (52.37 and 54.37 mg gallic acid equivalent/g) and flavonoids (74.13 and 80.75 mg rutin equivalent/g). Accordingly, the leaves methanol extracts showed the highest antioxidant potential. Interestingly, the roots methanol extracts were the most potent acetylcholinesterase (4.75 mg galantamine equivalent/g) and butyrylcholinesterase inhibitors (5.26 and 5.14 mg galantamine equivalent/g). The leaves and roots methanol extracts exhibited high α-glucosidase (2.48–3.08 mmol acarbose equivalent/g) and α-amylase (0.17−0.70 mmol acarbose equivalent/g) inhibition. The highest tyrosinase inhibition was recorded for leaves methanol extracts (138.79 and 140.34 mg kojic acid equivalent/g). 87 natural products (including hydroxybenzoic, hydroxycinnamic and acylquinic acids, flavones, flavonols, flavanones and anthocyanins) were unambiguously identified or tentatively annotated in the studied extracts. Findings presented in the present study appraise the bioactivity of R. iconiensis, an understudied species.

A comprehensive and cost-effective approach for investigating passive dispersal in minute invertebrates with case studies of phytophagous eriophyid mites

Dispersal is a fundamental biological process that operates at different temporal and spatial scales with consequences for individual fitness, population dynamics, population genetics, and species distributions. Studying this process is particularly challenging when the focus is on microscopic organisms that disperse passively, whilst controlling neither the transience nor the settlement phase of their movement. In this work we propose a comprehensive approach for studying passive dispersal of microscopic invertebrates and demonstrate it using wind and phoretic vectors. The protocol includes the construction of versatile, modifiable dispersal tunnels as well as a theoretical framework quantifying the movement of species via wind or vectors, and a hierarchical Bayesian approach appropriate to the structure of the dispersal data. The tunnels were used to investigate the three stages of dispersal (viz., departure, transience, and settlement) of two species of minute, phytophagous eriophyid mites Aceria tosichella and Abacarus hystrix. The proposed devices are inexpensive and easy to construct from readily sourced materials. Possible modifications enable studies of a wide range of mite species and facilitate manipulation of dispersal factors, thus opening a new important area of ecological study for many heretofore understudied species.

Under the Radar: Epidemiology of Plasmodium ovale in the Democratic Republic of the Congo.

Plasmodium ovale is an understudied malaria species prevalent throughout much of sub-Saharan Africa. Little is known about the distribution of ovale malaria and risk factors for infection in areas of high malaria endemicity. Using the 2013 Democratic Republic of the Congo (DRC) Demographic and Health Survey, we conducted a risk factor analysis for P. ovale infections. We evaluated geographic clustering of infections and speciated to P. ovale curtisi and P. ovale wallikeri through deep sequencing. Of 18 149 adults tested, we detected 143 prevalent P. ovale infections (prevalence estimate 0.8%; 95% confidence interval [CI], .59%-.98%). Prevalence ratios (PR) for significant risk factors were: male sex PR = 2.12 (95% CI, 1.38-3.26), coprevalent P. falciparum PR = 3.52 (95% CI, 2.06-5.99), and rural residence PR = 2.19 (95% CI, 1.31-3.66). P. ovale was broadly distributed throughout the DRC; an elevated cluster of infections was detected in the south-central region. Speciation revealed P. ovale curtisi and P. ovale wallikeri circulating throughout the country. P. ovale persists broadly in the DRC, a high malaria burden country. For successful elimination of all malaria species, P. ovale needs to be on the radar of malaria control programs.

Taro Genome Assembly and Linkage Map Reveal QTLs for Resistance to Taro Leaf Blight.

Taro (Colocasia esculenta) is a food staple widely cultivated in the humid tropics of Asia, Africa, Pacific and the Caribbean. One of the greatest threats to taro production is Taro Leaf Blight caused by the oomycete pathogen Phytophthora colocasiae. Here we describe a de novo taro genome assembly and use it to analyze sequence data from a Taro Leaf Blight resistant mapping population. The genome was assembled from linked-read sequences (10x Genomics; ∼60x coverage) and gap-filled and scaffolded with contigs assembled from Oxford Nanopore Technology long-reads and linkage map results. The haploid assembly was 2.45 Gb total, with a maximum contig length of 38 Mb and scaffold N50 of 317,420 bp. A comparison of family-level (Araceae) genome features reveals the repeat content of taro to be 82%, >3.5x greater than in great duckweed (Spirodela polyrhiza), 23%. Both genomes recovered a similar percent of Benchmarking Universal Single-copy Orthologs, 80% and 84%, based on a 3,236 gene database for monocot plants. A greater number of nucleotide-binding leucine-rich repeat disease resistance genes were present in genomes of taro than the duckweed, ∼391 vs. ∼70 (∼182 and ∼46 complete). The mapping population data revealed 16 major linkage groups with 520 markers, and 10 quantitative trait loci (QTL) significantly associated with Taro Leaf Blight disease resistance. The genome sequence of taro enhances our understanding of resistance to TLB, and provides markers that may accelerate breeding programs. This genome project may provide a template for developing genomic resources in other understudied plant species.

Genetic Diversity of Anopheles coustani (Diptera: Culicidae) in Malaria Transmission Foci in Southern and Central Africa.

Despite ongoing malaria control efforts implemented throughout sub-Saharan Africa, malaria remains an enormous public health concern. Current interventions such as indoor residual spraying with insecticides and use of insecticide-treated bed nets are aimed at targeting the key malaria vectors that are primarily endophagic and endophilic. Anopheles coustani s.l., an understudied vector of malaria, is a species previously thought to exhibit mostly zoophilic behavior. Like many of these understudied species, An. coustani has greater anthropophilic tendencies than previously appreciated, is often both endophagic and exophagic, and carries Plasmodium falciparum sporozoites. The aim of this study was to explore genetic variation of An. coustani mosquitoes and the potential of this species to contribute to malaria parasite transmission in high transmission settings in Zambia and the Democratic Republic of the Congo (DRC). Morphologically identified An. coustani specimens that were trapped outdoors in these study sites were analyzed by PCR and sequencing for species identification and bloodmeal sources, and malaria parasite infection was determined by ELISA and qPCR. Fifty An. coustani s.s. specimens were confirmed by analysis of mitochondrial DNA cytochrome c oxidase subunit I (COI) and ribosomal internal transcribed spacer region 2 (ITS2). Maximum likelihood phylogenetic analysis of COI and ITS2 sequences revealed two distinct phylogenetic groups within this relatively small regional collection. Our findings indicate that both An. coustani groups have anthropophilic and exophagic habits and come into frequent contact with P. falciparum, suggesting that this potential alternative malaria vector might elude current vector control measures in northern Zambia and southern DRC.

Singing behaviour of ruby‐crowned kinglets Regulus calendula in relation to time‐of‐day, time‐of‐year and social context

Observational field studies provide insight on the multifunctional nature of birdsong. For example, if song production were limited to pre‐fertilization, then that would suggest a mate attraction function. If it were used throughout the breeding season and in response to intruding males, then that would suggest a territorial defence function. In the present study, we determined the daily and seasonal singing patterns of male ruby‐crowned kinglets Regulus calendula in Labrador, Canada, using microphone arrays in two breeding seasons. Using a playback experiment, we simulated a territorial intrusion to compare the structure of songs produced while defending a territory to the structure of songs produced during solo and contest singing. Singing peaked in the early part of the breeding season and then declined continuously for the remainder of the season, which suggests that the songs function in mate attraction. Singing peaked 2–3 h after dawn, and then declined steadily until it stopped at 10 pm. Some nocturnal singing was observed, but no dawn singing was observed. A high probability of signal overlap by heterospecific songs at dawn would hinder signal recognition and explain the observed delay in peak singing activity. Vocal responses to playback suggested a function in territory defence. However, there were no significant differences in the duty cycle, frequency modulation and bandwidth of songs in relation to the context of song production, though songs were shorter in the intrusion context than during solo singing. Overall, the study provides the first quantitative description of the effects of time of day, time of year and social context on singing behaviour in this understudied species.

Transcriptome sequencing reveals signatures of positive selection in the Spot-Tailed Earless Lizard.

The continual loss of threatened biodiversity is occurring at an accelerated pace. High-throughput sequencing technologies are now providing opportunities to address this issue by aiding in the generation of molecular data for many understudied species of high conservation interest. Our overall goal of this study was to begin building the genomic resources to continue investigations and conservation of the Spot-Tailed Earless lizard. Here we leverage the power of high-throughput sequencing to generate the liver transcriptome for the Northern Spot-Tailed Earless Lizard (Holbrookia lacerata) and Southern Spot-Tailed Earless Lizard (Holbrookia subcaudalis), which have declined in abundance in the past decades, and their sister species, the Common Lesser Earless Lizard (Holbrookia maculata). Our efforts produced high quality and robust transcriptome assemblies validated by 1) quantifying the number of processed reads represented in the transcriptome assembly and 2) quantifying the number of highly conserved single-copy orthologs that are present in our transcript set using the BUSCO pipeline. We found 1,361 1-to-1 orthologs among the three Holbrookia species, Anolis carolinensis, and Sceloporus undulatus. We carried out dN/dS selection tests using a branch-sites model and identified a dozen genes that experienced positive selection in the Holbrookia lineage with functions in development, immunity, and metabolism. Our single-copy orthologous sequences additionally revealed significant pairwise sequence divergence (~.73%) between the Northern H. lacerata and Southern H. subcaudalis that further supports the recent elevation of the Southern Spot-Tailed Earless Lizard to full species.

Morphology and life cycle of an epiphytic pherusellid ctenostome bryozoan from the Mediterranean Sea

The epiphytic community on the endemic seagrass Posidonia oceanica from the Mediterranean Sea is well studied, but still harbors some little investigated epiphytic bryozoans. Numerous, yet always small colonies of Pherusella sp. were recently encountered in the Northern Adriatic Sea. The aim of this study was to generate data on the life history, colonial development, and reproduction of the Mediterranean population of this Pherusella species in order to gain a better understanding of the biology of this understudied species. The morphology of adult zooids was also studied due to the lack of recent data on the family with state-of-the-art techniques. Long-term observation shows that this species is highly adapted to an epiphytic life cycle with short generation time throughout the year. First laboratory cultures appear promising in establishing a reliable model system for developmental and ecological studies. Larvae are easily obtainable, and metamorphosis and colonial growth patterns are documented here for the first time. The morphology of adults shows distinct similarities with other pheruselllids and, along with the neuromuscular system, is similar to other alcyonidioideans supporting the close relationship of these taxa. This study constitutes one of the first long-time observations of the life cycle and colonial growth of a pherusellid bryozoan, including morphological data about the neuromuscular system of an otherwise incompletely known group of bryozoans. Pherusella sp. appears to be a promising candidate for future studies since it is easy to collect and maintain under laboratory conditions as well as to obtain different developmental stages.

Trace elements in feathers of Cape Petrel (Daption capense) from Antarctica

The Cape petrel (Daption capense) has circumpolar distribution and potential to be used as sentinels of trace elements levels in the Antarctic environment. This study measured trace elements in carcass feathers (n = 30) of this yet under-studied Procellariiform species, in King George Island, Antarctica. This non-invasive sampling method was useful for quantifying mercury (Hg), cadmium (Cd), selenium (Se), and to perform the sex identification of birds. There were no significant differences between males and females for Hg (mean ± SD, 973 ± 930 ng g−1; 977 ± 570 ng g−1) and Se (3919 ± 637 ng g−1; 3782 ± 799 ng g−1), levels but males had significantly lower Cd levels than females (101 ± 76 ng g−1; 293 ± 251 ng g−1), respectively. Hg concentration in D. capense is lower than other Procellariiformes which indicate interspecific variations that may be related to their proximity to pollution sources. The reason for males having significantly lower Cd levels than females is unknown. This opportunistic and non-invasive sampling strategy can be useful in the environmental monitoring of the trace elements in polar environments.

Ecology of the Western Queen Butterfly Danaus gilippus thersippus (Lepidoptera: Nymphalidae) in the Mojave and Sonoran Deserts.

The purpose of this study was to assess the ecological knowledge surrounding the western queen butterfly, Danaus gilippus thersippus (H. Bates). Specifically, our objectives were to synthesize existing data and knowledge on the ecology of the queen and use results of this assessment to inform the direction of future research on this understudied species. We identified six core areas for assessment: distribution, the biodiversity of plant resources, western queen and their host plant phenology, chemical ecology, and four key life history traits. We mapped the distribution of D. g. thersippus from museum specimen records, citizen science (e.g., iNaturalist) and image sharing app-based observations, along with other observational data enumerating all current known plant resources and long-range movements. We assembled 14 larval food plants, six pyrrolizidine alkaloids plants and six nectar plants distributed in the western Mojave and Sonoran Desert regions of the United States and Baja California. We report on its phenology and its long-range movement. Butterfly species have declined across the western US, and western monarch populations have declined by 97%. Danaus g. thersippus has received little research attention compared with its famous congener D. plexippus L. Danaus g. thersippus’ desert distribution may be at its temperature limits for the species distribution and for its rare host plant Asclepias nyctaginifolia.

Wild dogs at stake: deforestation threatens the only Amazon endemic canid, the short-eared dog (Atelocynus microtis).

The persistent high deforestation rate and fragmentation of the Amazon forests are the main threats to their biodiversity. To anticipate and mitigate these threats, it is important to understand and predict how species respond to the rapidly changing landscape. The short-eared dog Atelocynus microtis is the only Amazon-endemic canid and one of the most understudied wild dogs worldwide. We investigated short-eared dog habitat associations on two spatial scales. First, we used the largest record database ever compiled for short-eared dogs in combination with species distribution models to map species habitat suitability, estimate its distribution range and predict shifts in species distribution in response to predicted deforestation across the entire Amazon (regional scale). Second, we used systematic camera trap surveys and occupancy models to investigate how forest cover and forest fragmentation affect the space use of this species in the Southern Brazilian Amazon (local scale). Species distribution models suggested that the short-eared dog potentially occurs over an extensive and continuous area, through most of the Amazon region south of the Amazon River. However, approximately 30% of the short-eared dog's current distribution is expected to be lost or suffer sharp declines in habitat suitability by 2027 (within three generations) due to forest loss. This proportion might reach 40% of the species distribution in unprotected areas and exceed 60% in some interfluves (i.e. portions of land separated by large rivers) of the Amazon basin. Our local-scale analysis indicated that the presence of forest positively affected short-eared dog space use, while the density of forest edges had a negative effect. Beyond shedding light on the ecology of the short-eared dog and refining its distribution range, our results stress that forest loss poses a serious threat to the conservation of the species in a short time frame. Hence, we propose a re-assessment of the short-eared dog's current IUCN Red List status (Near Threatened) based on findings presented here. Our study exemplifies how data can be integrated across sources and modelling procedures to improve our knowledge of relatively understudied species.

Unravelling the phenology of Ixodes frontalis, a common but understudied tick species in Europe

Unravelling the phenology of Ixodes frontalis, a common but understudied tick species in Europe

Unexpected massive enmeshments of the Sharpchin barracudina Paralepis coregonoides Risso, 1820 in mesopelagic sediment traps in the Levantine Basin, SE Mediterranean Sea

This study reports exceptional penetrations of the Sharpchin Barracudina Paralepis coregonoides into pelagic, open-sea sediment traps in the Levant Basin of the SE Mediterranean Sea. This first substantiated record of the species at the Levant Basin has been observed in two sediment traps at 180 and 280 m depth, 50 km offshore the coast of Israel. Over one year of deployment (November 2016 till November 2017), 483 adult individuals have been repeatedly entrapped inside the automatic sediment traps that were covered with a 25 mm baffler mesh for the first half year and then replaced with a smaller 1 cm mesh for the second half. This undesirable catch of such an elusive and understudied species provided a unique opportunity to revise its distribution, abundance and genetic divergence. The continuous entrapment throughout the year of sexually mature individuals has confirmed that this species is common to the SE Mediterranean. In order to avoid unwanted entrapments that disrupt biogeochemical sediment studies, the installation of small mesh size nets on the conventional sediment trap openings must be considered in the pelagic zone of the SE Mediterranean, and probably elsewhere.

The Genome of Caenorhabditis bovis.

The free-living nematode Caenorhabditis elegans is akey laboratory model for metazoan biology. C.elegans has also become a model for parasitic nematodes despite being only distantly related to most parasitic species. All of the ∼65 Caenorhabditis species currently in culture are free-living, with most having been isolated from decaying plant or fungal matter. Caenorhabditis bovis is a particularly unusual species that has been isolated several times from the inflamed ears of Zebu cattle in Eastern Africa, where it is associated with thedisease bovine parasitic otitis. C.bovis is therefore of particular interest to researchers interested in the evolution of nematode parasitism. However, as C.bovis is not in laboratory culture, it remains little studied. Here, by sampling livestock markets and slaughterhouses in Western Kenya, we successfully reisolated C.bovis from the ear of adult female Zebu. We sequenced the genome of C.bovis using the Oxford Nanopore MinION platform in a nearby field laboratory and used the data to generate a chromosome-scaledraft genome sequence. We exploited this draft genome sequence to reconstruct the phylogenetic relationships of C.bovis to other Caenorhabditis species and reveal the changes in genome size and content that have occurred during its evolution. We also identified expansions in several gene families that have been implicated in parasitism in other nematode species. The high-quality draft genome and our analyses thereof represent a significant advancement in our understanding of this unusual Caenorhabditis species.

Resolving fine-scale population structure and fishery exploitation using sequenced microsatellites in a northern fish.

The resiliency of populations and species to environmental change is dependent on the maintenance of genetic diversity, and as such, quantifying diversity is central to combating ongoing widespread reductions in biodiversity. With the advent of next‐generation sequencing, several methods now exist for resolving fine‐scale population structure, but the comparative performance of these methods for genetic assignment has rarely been tested. Here, we evaluate the performance of sequenced microsatellites and a single nucleotide polymorphism (SNP) array to resolve fine‐scale population structure in a critically important salmonid in north eastern Canada, Arctic Charr (Salvelinus alpinus). We also assess the utility of sequenced microsatellites for fisheries applications by quantifying the spatial scales of movement and exploitation through genetic assignment of fishery samples to rivers of origin and comparing these results with a 29‐year tagging dataset. Self‐assignment and simulation‐based analyses of 111 genome‐wide microsatellite loci and 500 informative SNPs from 28 populations of Arctic Charr in north‐eastern Canada identified largely river‐specific genetic structure. Despite large differences (~4X) in the number of loci surveyed between panels, mean self‐assignment accuracy was similar with the microsatellite loci and the SNP panel (>90%). Subsequent analysis of 996 fishery‐collected samples using the microsatellite panel revealed that larger rivers contribute greater numbers of individuals to the fishery and that coastal fisheries largely exploit individuals originating from nearby rivers, corroborating results from traditional tagging experiments. Our results demonstrate the efficacy of sequence‐based microsatellite genotyping to advance understanding of fine‐scale population structure and harvest composition in northern and understudied species.

Are we overestimating risk of enteric pathogen spillover from wild birds to humans?

ABSTRACTEnteric illnesses remain the second largest source of communicable diseases worldwide, and wild birds are suspected sources for human infection. This has led to efforts to reduce pathogen spillover through deterrence of wildlife and removal of wildlife habitat, particularly within farming systems, which can compromise conservation efforts and the ecosystem services wild birds provide. Further, Salmonella spp. are a significant cause of avian mortality, leading to additional conservation concerns. Despite numerous studies of enteric bacteria in wild birds and policies to discourage birds from food systems, we lack a comprehensive understanding of wild bird involvement in transmission of enteric bacteria to humans. Here, we propose a framework for understanding spillover of enteric pathogens from wild birds to humans, which includes pathogen acquisition, reservoir competence and bacterial shedding, contact with people and food, and pathogen survival in the environment. We place the literature into this framework to identify important knowledge gaps. Second, we conduct a meta‐analysis of prevalence data for three human enteric pathogens, Campylobacter spp., E. coli, and Salmonella spp., in 431 North American breeding bird species. Our literature review revealed that only 3% of studies addressed the complete system of pathogen transmission. In our meta‐analysis, we found a Campylobacter spp. prevalence of 27% across wild birds, while prevalence estimates of pathogenic E. coli (20%) and Salmonella spp. (6.4%) were lower. There was significant bias in which bird species have been tested, with most studies focusing on a small number of taxa that are common near people (e.g. European starlings Sturnus vulgaris and rock pigeons Columba livia) or commonly in contact with human waste (e.g. gulls). No pathogen prevalence data were available for 65% of North American breeding bird species, including many commonly in contact with humans (e.g. black‐billed magpie Pica hudsonia and great blue heron Ardea herodias), and our metadata suggest that some under‐studied species, taxonomic groups, and guilds may represent equivalent or greater risk to human infection than heavily studied species. We conclude that current data do not provide sufficient information to determine the likelihood of enteric pathogen spillover from wild birds to humans and thus preclude management solutions. The primary focus in the literature on pathogen prevalence likely overestimates the probability of enteric pathogen spillover from wild birds to humans because a pathogen must survive long enough at an infectious dose and be a strain that is able to colonize humans to cause infection. We propose that future research should focus on the large number of under‐studied species commonly in contact with people and food production and demonstrate shedding of bacterial strains pathogenic to humans into the environment where people may contact them. Finally, studies assessing the duration and intensity of bacterial shedding and survival of bacteria in the environment in bird faeces will help provide crucial missing information necessary to calculate spillover probability. Addressing these essential knowledge gaps will support policy to reduce enteric pathogen spillover to humans and enhance bird conservation efforts that are currently undermined by unsupported fears of pathogen spillover from wild birds.

Current and future suitable habitat areas for Nasuella olivacea (Gray, 1865) in Colombia and Ecuador and analysis of its distribution across different land uses.

Nasuella olivacea is an endemic mammal from the Andes of Ecuador and Colombia. Due to its rarity, aspects about its natural history, ecology and distribution patterns are not well known, therefore, research is needed to generate knowledge about this carnivore and a first step is studying suitable habitat areas. We performed Ecological Niche Models and applied future climate change scenarios (2.6 and 8.5 RCP) to determine the potential distribution of this mammal in Colombia and Ecuador, with current and future climate change conditions; furthermore, we analysed its distribution along several land covers. We found that N. olivacea is likely to be found in areas where no records have been reported previously; likewise, climate change conditions would increase suitable distribution areas. Concerning land cover, 73.4% of N. olivacea potential distribution was located outside Protected Areas (PA), 46.1% in Forests and 40.3% in Agricultural Lands. These findings highlight the need to further research understudied species, furthering our understanding about distribution trends and responses to changing climatic conditions, as well as informig future PA designing. These are essential tools for supporting wildlife conservation plans, being applicable for rare species whose biology and ecology remain unknown.

Potential distribution and population trends of the smalltail shark Carcharhinus porosus inferred from species distribution models and historical catch data

Abstract Updated distribution ranges are crucial for conservation status assessments. Comprehensive analyses combining published literature and available data on historical catches and species distribution models (SDMs) are effective tools that could improve the prediction of more realistic scenarios for some species, especially those with limited information available and facing multiple threats. The present study aimed at generating an updated distribution for the smalltail shark Carcharhinus porosus, one of the most threatened and understudied shark species of the western Atlantic Ocean. Estimates of the key areas for this species conservation based on the SDMs, and trends in catch probabilities throughout its distribution range are provided. Four algorithms (BIOCLIM, Domain, Mahalanobis, and Maximum Entropy) were used to model the distribution of C. porosus and calculate its habitat suitability based on marine environmental variables. To assess historical catch probability trends, we built a generalized linear model from published and grey literature data. This analysis was used to estimate catch probability as an indication of population trends. SDMs suggest that the northern coast of South America (NCSA) harbours the most suitable habitats for C. porosus in the world, which was expected given its historically high catch rate in this region. In addition, there was a continuously declining catch probability trend starting in the 1970s. However, the decline was smaller for the NCSA as compared with the Gulf of Mexico and the eastern South America coast. Results indicate that the NCSA should be considered the currently most important area in the world for this species conservation. Furthermore, the lack of data throughout Central and South American marine regions hampers the evaluation of extinction risk throughout its updated distribution. Thus, research in these areas is urgently required for a more comprehensive conservation status assessment.