Javier Nori

American bullfrog invasion in Argentina: where should we take urgent measures?

Argentina is the country with the most geographically extended biological invasion of the American bullfrog (Lithobates catesbeianus) in South America after Brazil. Here, we used a maximum entropy ecological niche modeling algorithm (using records of the native range of American bullfrog) to project the model onto the whole of Argentina. We determined the most suitable habitats for this invasive alien species and where we consider urgent measures should be taken. Our projections showed good agreement with known feral populations of American bullfrog in Argentina. By implementing the “Multivariate Environmental Similarity Surface” analysis, we be able to determine that factors such as low precipitations or highest altitudes could be limiting the species’ ability to invade the west and south of the country. We suggest that strategies should focus on detecting established feral populations of the American bullfrog and preventing further introductions or range expansion of feral populations in the northeast portion of the country. Lastly, we report a new feral population of bullfrogs in Argentina.

Biogeographic regions of Central Argentina based on snake distribution: evaluating two different methodological approaches

Regionalization studies attempt to divide an area into regions by studying the distribution of its biota. Here we used snake distribution in Central Argentina to recognize distribution patterns, and then compared two methods (cluster analysis and endemism analysis) and the patterns found with previously defined regions. Both analyses recovered Chaco and, within Chaco, the subregion Chaco Serrano, as well as all the snake species that are threatened or range-restricted occurring only in the Chaco region, which has been severely deforested in the last decades. The Espinal region was not recovered by cluster analysis or NDM software, and may be considered an “impoverished” Chaco or a transition zone. The Pampas was only recovered by cluster analysis. NDM appears to be more robust than cluster analysis, whereas the latter seems to be very sensitive to sampling problems, sometimes identifying spurious areas or areas characterized by having no exclusive species.

On the worrying fate of Data Deficient amphibians.

The ‘Data Deficient’ (DD) category of the IUCN Red List assembles species that cannot be placed in another category due to insufficient information. This process generates uncertainty about whether these species are safe or actually in danger. Here, we give a global overview on the current situation of DD amphibian species (almost a quarter of living amphibians) considering land-use change through habitat modification, the degree of protection of each species and the socio-political context of each country harboring DD species. We found that DD amphibians have, on average, 81% of their ranges totally outside protected areas. Worryingly, more than half of DD species have less than 1% of their distribution represented in protected areas. Furthermore, the percentage of overlap between species’ range and human-modified landscapes is high, at approximately 58%. Many countries harboring a large number of DD species show a worrying socio-political trend illustrated by substantial, recent incremental increases in the Human Development Index and lower incremental increases in the establishment of protected areas. Most of these are African countries, which are located mainly in the central and southern regions of the continent. Other countries with similar socio-political trends are in southeastern Asia, Central America, and in the northern region of South America. This situation is concerning, but it also creates a huge opportunity for considering DD amphibians in future conservation assessments, planning, and policy at different levels of government administration.

Anfibios de las Sierras Pampeanas Centrales de Argentina: diversidad y distribución altitudinal

Las Sierras Pampeanas Centrales (SPC) ocupan parte del territorio de las provincias de Cordoba y San Luis (Argentina) y constituyen un area de singular importancia biogeografica. En este trabajo se presenta una sintesis sobre el conocimiento de la diversidad y distribucion altitudinal de la fauna de anuros de las Sierras de Cordoba y San Luis. El listado de especies de anfibios de las SPC se compilo utilizando diversas fuentes de informacion (datos de campo, colecciones biologicas y registros bibliograficos). Utilizando esta informacion se caracterizo el rango de distribucion altitudinal de cada especie y se analizaron las asociaciones entre la riqueza y composicion de anfibios y el gradiente de altura de las SPC. Se registro un total de 22 especies de anfibios pertenecientes a cinco familias. Dicha fauna se distribuye de forma heterogenea en el gradiente de altura de las SPC observandose una disminucion lineal de la riqueza en funcion de la altura y ensambles asociados a sectores altitudinales definidos. Los resultados obtenidos representan informacion basica y necesaria para evaluar el impacto de diversas actividades humanas en este particular y fragil sistema de montana