Conservation Assessment of Southern South American Freshwater Ecoregions on the Basis of the Distribution and Genetic Diversity of Crabs from the Genus Aegla

Abstract

We assessed the conservation priority of 18 freshwater ecoregions in southern South America on the basis of Aegla (genus of freshwater crabs) genetic diversity and distribution. Geographical distributions for 66 Aegla species were taken from the literature and plotted against ecoregions and main river basins of southern South America. Species richness and number of threatened and endemic species were calculated for each area. To assess taxonomic and phylogenetic diversity, we generated a molecular phylogeny based on DNA sequences for one nuclear (28S) and 4 mitochondrial (12S, 16S, COI, and COII) genes. All species richness and phylogenetic methods agreed, to a large extent, in their rankings of the importance of conservation areas, as indicated by the Spearman's rank correlation coefficient (p < 0.01); nonetheless, some of the lowest correlations were observed between taxonomic and phylogenetic diversity indices. The 5 ecoregions of the Laguna dos Patos Basin (Eastern Brazil), Central Chile, South Brazilian Coast, Chilean Lakes, and Subtropical Potamic Axis (northern Argentina and southern Uruguay and Paraguay) had the highest biodiversity scores. Conservation of these regions will preserve the largest number of species and the greatest amount of genetic diversity within the South American freshwater Aegla fauna. Biodiversity across rivers and within areas was heterogeneously distributed in the ecoregions of Upper Paraná, Ribeira do Iguape, Upper Uruguay, and South Brazilian Coast (i.e., one river showed significantly more biodiversity than any other river from the same ecoregion), but homogeneously distributed in the other ecoregions. Hence, conservation plans in the former regions will potentially require less effort than plans in the latter regions.

Diversity and conservation status of Aegla spp. (Anomura, Aeglidae): an update

“…This proportion represents a significant increase in relation to previous assessments for the genus Aegla, which estimated nearly half of the present value (Bond-Buckup et al, 2008;Pérez-Losada et al, 2009). Considering the most recent conservation status assessment for each species, from the 32 species previously assessed as LC, only 20 kept the same status; nine species changed the category to some level of threat and three have deficient data.…”

Biodiversity only makes sense in the light of evolution

“…When we consider evolutionary heritage, it is clear that knowledge of phylogenetic relationships can inform conservation priorities (Faith 1992;Whiting et al 2000;Pérez-Losada et al 2009). In this context, the 'phylogenetic diversity' (PD) measure, which incorporates phylogenetic and trait differences among species, is particularly useful (Faith 1992, Forest et al 2007.…”

High genetic differentiation of Aegla longirostri (Crustacea, Decapoda, Anomura) populations in southern Brazil revealed by multi-loci microsatellite analysis

“…Further studies involving other populations of this species and even other molecular markers would help to test this hypothesis. Several species of aeglids are threatened (Bond-Buckup et al, 2008;Pérez-Losada et al, 2009) and cryptic species probably have a very narrow distribution, like most Aegla species, making them of significant conservation concern. This may be the case of the population occurring in Ibicuí-Mirim River, the southern limit of Atlantic Forest, which would be under threat considering its very restricted distribution range, among other factors.…”

“…Species richness is greater than that of both marine and terrestrial ecosystems, when considering the habitat extent in freshwater ecosystems (Silk, 2005). On the other hand, the world's freshwater biodiversity is among the most threatened and deserves urgent conservation care (Abell, 2002;Pérez-Losada et al, 2009).…”