Monday, November 27, 2017

[Herpetology • 2017] Patterns, Biases and Prospects in the Distribution and Diversity of Neotropical Snakes


 Figure 1. Neotropical region and ecoregion limits adopted here (sensu Olson et al., 2001), together with representative snakes species recorded for
Central America Montane Forests: 1.1 Boa constrictor, 1.2 Oxybelis aeneus;
Amazonia Most Forests: 1.3 Philodryas argentea, 1.4 Rhinobothryum lentiginosum, 1.5 Eunectes murinus, 1.6 Siphlophis compressus, 1.7 Amerotyphlops reticulatus, 1.8 Lachesis muta;
Cerrado: 1.9 Imantodes cenchoa, 1.10 Apostolepis flavotorquata, 1.11 Bothrops lutzi, 1.12 Micrurus frontalis, 1.13 Erythrolamprus typhlus, 1.14 Phalotris lativittatus, 1.15 Xenopholis undulatus, 1.16 Oxyrhopus rhombifer, 1.17 Rhachidelus brazili;
 Chaco: 1.18 Psomophis genimaculatus, 1.19 Philodryas baroni, 1.20 Phimophis vittatus;
Guianian Moist Forests: 1.21 Corallus caninus, 1.22 Anilius scytale, 1.23 Amerotyphlops brongersmianus;
 Caatinga: 1.24 Erythrolamprus viridis, 1.25 Thamnodynastes phoenix, 1.26 Bothrops erythromelas;
and in the Atlantic Forest: 1.27 Atractus maculatus, 1.28 Chironius bicarinatus, 1.29 Tropidodryas striaticeps, 1.30 Liotyphlops beui, 1.31 Oxyrhopus guibei, 1.32 Dipsas albifrons, 1.33 Bothrops jararaca, 1.34 Corallus hortulanus, 1.35 Erythrolamprus atraventer.

 The abbreviations indicate common life habits of the Neotropical snakes: aquatic (Aq), arboreal (Ar), fossorial (F), terrestrial (T).
 Photograph credits: Cristiano C. Nogueira (10, 12), Crizanto C. Brito (27), Henrique B. Braz (14), Ivan Sazima (24, 35), Luiz C. Turci (7), Marcio Martins (4), Marco Sena (6), Martin Jansen (9, 13, 18, 23, 31), Otavio A. V. Marques (2, 3, 5, 15, 16, 17, 19, 20, 21, 22, 28, 30, 32), Ricardo J. Sawaya (33), Thaís B. Guedes (1, 8, 11, 25, 26, 29, 34)

Guedes, Sawaya, Zizka, et al. 2017.  DOI: 10.1111/geb.12679 


Abstract

Motivation
We generated a novel database of Neotropical snakes (one of the world's richest herpetofauna) combining the most comprehensive, manually compiled distribution dataset with publicly available data. We assess, for the first time, the diversity patterns for all Neotropical snakes as well as sampling density and sampling biases.

Main types of variables contained
We compiled three databases of species occurrences: a dataset downloaded from the Global Biodiversity Information Facility (GBIF), a verified dataset built through taxonomic work and specialized literature, and a combined dataset comprising a cleaned version of the GBIF dataset merged with the verified dataset.

Spatial location and grain

Neotropics, Behrmann projection equivalent to 1° × 1°.

Time period

Specimens housed in museums during the last 150 years.

Major taxa studied
Squamata: Serpentes.

Software format
Geographical information system (GIS).

Results

The combined dataset provides the most comprehensive distribution database for Neotropical snakes to date. It contains 147,515 records for 886 species across 12 families, representing 74% of all species of snakes, spanning 27 countries in the Americas. Species richness and phylogenetic diversity show overall similar patterns. Amazonia is the least sampled Neotropical region, whereas most well-sampled sites are located near large universities and scientific collections. We provide a list and updated maps of geographical distribution of all snake species surveyed.

Main conclusions

The biodiversity metrics of Neotropical snakes reflect patterns previously documented for other vertebrates, suggesting that similar factors may determine the diversity of both ectothermic and endothermic animals. We suggest conservation strategies for high-diversity areas and sampling efforts be directed towards Amazonia and poorly known species.


 Figure 1. Neotropical region and ecoregion limits adopted here (sensu Olson et al., 2001), together with representative snakes species recorded for
Central America Montane Forests: 1.1 Boa constrictor, 1.2 Oxybelis aeneus;
Amazonia Most Forests: 1.3 Philodryas argentea, 1.4 Rhinobothryum lentiginosum, 1.5 Eunectes murinus, 1.6 Siphlophis compressus, 1.7 Amerotyphlops reticulatus, 1.8 Lachesis muta;
Cerrado: 1.9 Imantodes cenchoa, 1.10 Apostolepis flavotorquata, 1.11 Bothrops lutzi, 1.12 Micrurus frontalis, 1.13 Erythrolamprus typhlus, 1.14 Phalotris lativittatus, 1.15 Xenopholis undulatus, 1.16 Oxyrhopus rhombifer, 1.17 Rhachidelus brazili;
 Chaco: 1.18 Psomophis genimaculatus, 1.19 Philodryas baroni, 1.20 Phimophis vittatus;
Guianian Moist Forests: 1.21 Corallus caninus, 1.22 Anilius scytale, 1.23 Amerotyphlops brongersmianus;
 Caatinga: 1.24 Erythrolamprus viridis, 1.25 Thamnodynastes phoenix, 1.26 Bothrops erythromelas;
and in the Atlantic Forest: 1.27 Atractus maculatus, 1.28 Chironius bicarinatus, 1.29 Tropidodryas striaticeps, 1.30 Liotyphlops beui, 1.31 Oxyrhopus guibei, 1.32 Dipsas albifrons, 1.33 Bothrops jararaca, 1.34 Corallus hortulanus, 1.35 Erythrolamprus atraventer.

 The abbreviations indicate common life habits of the Neotropical snakes: aquatic (Aq), arboreal (Ar), fossorial (F), terrestrial (T).
 Photograph credits: Cristiano C. Nogueira (10, 12), Crizanto C. Brito (27), Henrique B. Braz (14), Ivan Sazima (24, 35), Luiz C. Turci (7), Marcio Martins (4), Marco Sena (6), Martin Jansen (9, 13, 18, 23, 31), Otavio A. V. Marques (2, 3, 5, 15, 16, 17, 19, 20, 21, 22, 28, 30, 32), Ricardo J. Sawaya (33), Thaís B. Guedes (1, 8, 11, 25, 26, 29, 34)

Guedes, Sawaya, Zizka, et al. 2017.  DOI: 10.1111/geb.12679 

 CONCLUSIONS
Our study demonstrates that Neotropical snake diversity is unevenly distributed, with some ecoregions, such as the Cerrado, containing a disproportionately high diversity. We also showed that merging public and manually compiled data sources is likely to provide the largest taxonomic and geographical coverage for any system under study. However, a proper taxonomic verification, examination and assessment of biases of the public dataset proved crucial. As a result, we can now provide a solid and reliable foundation for any kind of meta-analysis, including the assessment of climate change effects, conservation strategies or design of future research agendas. Conservation priorities should focus on areas of high diversity values as well as high threat by landscape changes. Finally, we found highest diversity values in forested areas, reinforcing the need for general habitat protection compared with actions that are targeting specific species.

In order to increase our knowledge about Neotropical snakes, a geographically and taxonomically focused sampling is required, targeting Amazonia and those species whose distributions are so far largely unknown.


Thaís B. Guedes, Ricardo J. Sawaya, Alexander Zizka, Shawn Laffan, Søren Faurby, R. Alexander Pyron, Renato S. Bérnils, Martin Jansen, Paulo Passos, Ana L. C. Prudente, Diego F. Cisneros-Heredia, Henrique B. Braz, Cristiano de C. Nogueira and Alexandre Antonelli. 2017. Patterns, Biases and Prospects in the Distribution and Diversity of Neotropical Snakes. Global Ecology and Biogeography. DOI: 10.1111/geb.12679
ResearchGate.net/publication/321265035_Patterns_biases_and_prospects_in_the_distribution_and_diversity_of_Neotropical_snakes

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