Dataset Information

Combining species distribution modeling and field surveys to reappraise the geographic distribution and conservation status of the threatened thin-spined porcupine (Chaetomys subspinosus).

ABSTRACT: The threatened thin-spined porcupine (Chaetomys subspinosus), a forest-specialist endemic to the Brazilian Atlantic forest, was rarely detected in the wild during the 20th century. Previous geographic distribution assessments were carried out nearly three decades ago and were based on interview data. We performed extensive field surveys (based on active search and interviews), a literature review, and species distribution modeling to predict and validate a more reliable picture of its geographic distribution and environmental suitability gradient. We identified the main predictors of species' incidence, its conservation status, and pinpointed key areas for species conservation. Our results indicated that C. subspinosus is distributed continuously in the Atlantic forest from southeastern Espirito Santo to central-eastern Sergipe state, totaling 104,326 km2 of occurrence area, although only 3,299 km2 (13.3%) is currently represented by native forests (species habitat). C. subspinosus was absent or at least so rare that it was not detected in more than half of the locations sampled by interviews (53.5%). Our results suggest that populations are sensitive to climatic conditions and habitat loss, becoming abruptly rarer when the remaining forest cover reaches less than 10% area within a region (~ 5,000 km2 scale). This result indicates that the high deforestation level of the Atlantic forest is already close to the limit of regional species resistance. Bahia state still harbors the bulk of the remaining forest with high climatic suitability, and generally under low levels of legal protection. Herein we highlight priority areas and research gaps that could guide decision makers to promote conservation strategies for this threatened species.

SUBMITTER: Gine GAF

PROVIDER: S-EPMC6258534 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Combining species distribution modeling and field surveys to reappraise the geographic distribution and conservation status of the threatened thin-spined porcupine (Chaetomys subspinosus).

Giné Gastón Andrés Fernandez GAF Faria Deborah D

PloS one 20181127 11

The threatened thin-spined porcupine (Chaetomys subspinosus), a forest-specialist endemic to the Brazilian Atlantic forest, was rarely detected in the wild during the 20th century. Previous geographic distribution assessments were carried out nearly three decades ago and were based on interview data. We performed extensive field surveys (based on active search and interviews), a literature review, and species distribution modeling to predict and validate a more reliable picture of its geographic ...[more]

PMID: 30481222

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Project description:BACKGROUND: The thin-spined porcupine, also known as the bristle-spined rat, Chaetomys subspinosus (Olfers, 1818), the only member of its genus, figures among Brazilian endangered species. In addition to being threatened, it is poorly known, and even its taxonomic status at the family level has long been controversial. The genus Chaetomys was originally regarded as a porcupine in the family Erethizontidae, but some authors classified it as a spiny-rat in the family Echimyidae. Although the dispute seems to be settled in favor of the erethizontid advocates, further discussion of its affinities should be based on a phylogenetic framework. In the present study, we used nucleotide-sequence data from the complete mitochondrial cytochrome b gene and karyotypic information to address this issue. Our molecular analyses included one individual of Chaetomys subspinosus from the state of Bahia in northeastern Brazil, and other hystricognaths. RESULTS: All topologies recovered in our molecular phylogenetic analyses strongly supported Chaetomys subspinosus as a sister clade of the erethizontids. Cytogenetically, Chaetomys subspinosus showed 2n = 52 and FN = 76. Although the sexual pair could not be identified, we assumed that the X chromosome is biarmed. The karyotype included 13 large to medium metacentric and submetacentric chromosome pairs, one small subtelocentric pair, and 12 small acrocentric pairs. The subtelocentric pair 14 had a terminal secondary constriction in the short arm, corresponding to the nucleolar organizer region (Ag-NOR), similar to the erethizontid Sphiggurus villosus, 2n = 42 and FN = 76, and different from the echimyids, in which the secondary constriction is interstitial. CONCLUSION: Both molecular phylogenies and karyotypical evidence indicated that Chaetomys is closely related to the Erethizontidae rather than to the Echimyidae, although in a basal position relative to the rest of the Erethizontidae. The high levels of molecular and morphological divergence suggest that Chaetomys belongs to an early radiation of the Erethizontidae that may have occurred in the Early Miocene, and should be assigned to its own subfamily, the Chaetomyinae.

Project description:Species distribution models (SDMs) have become important and essential tools in conservation and management. However, SDMs built with count data, referred to as species abundance models (SAMs), are still less commonly used to date, but increasingly receiving attention. Species occurrence and abundance do not frequently display similar patterns, and often they are not even well correlated. Therefore, only using information based on SDMs or SAMs leads to an insufficient or misleading conservation efforts. How to combine information from SDMs and SAMs and how to apply the combined information to achieve unified conservation remains a challenge. In this study, we introduce and propose a priority protection index (PI). The PI combines the prediction results of the occurrence and abundance models. As a case study, we used the best-available presence and count records for an endangered farmland species, the Great Bustard (Otis tarda dybowskii), in Bohai Bay, China. We then applied the Random Forest algorithm (Salford Systems Ltd. Implementation) with eleven predictor variables to forecast the spatial occurrence as well as the abundance distribution. The results show that the occurrence model had a decent performance (ROC: 0.77) and the abundance model had a RMSE of 26.54. It is noteworthy that environmental variables influenced bustard occurrence and abundance differently. The area of farmland, and the distance to residential areas were the top important variables influencing bustard occurrence. While the distance to national roads and to expressways were the most important influencing abundance. In addition, the occurrence and abundance models displayed different spatial distribution patterns. The regions with a high index of occurrence were concentrated in the south-central part of the study area; and the abundance distribution showed high populations occurrence in the central and northwestern parts of the study area. However, combining occurrence and abundance indices to produce a priority protection index (PI) to be used for conservation could guide the protection of the areas with high occurrence and high abundance (e.g., in Strategic Conservation Planning). Due to the widespread use of SDMs and the easy subsequent employment of SAMs, these findings have a wide relevance and applicability than just those only based on SDMs or SAMs. We promote and strongly encourage researchers to further test, apply and update the priority protection index (PI) elsewhere to explore the generality of these findings and methods that are now readily available.

Dataset Information

Combining species distribution modeling and field surveys to reappraise the geographic distribution and conservation status of the threatened thin-spined porcupine (Chaetomys subspinosus).

Publications

Combining species distribution modeling and field surveys to reappraise the geographic distribution and conservation status of the threatened thin-spined porcupine (Chaetomys subspinosus).

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