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National Science Foundation SPECIATION IN PATAGONIA: Establishing Sustainable International Collaborations in Evolution, Ecology, and Conservation Biology

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 Speciation in Patagonia
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Crabs

Investigators

Freshwater Crabs

The Aeglidae are the most abundant and widely distributed freshwater decapod “crabs” in southern South America. Unlike true brachyuran crabs, however, in aeglids the fifth pair of pereiopods is reduced in size, lacking walking capacity (Martin & Abele, 1988); they also possess tiny chelae with which they groom branchiae and eggs attached to female's pleopods and the abdomen's underbelly (Martin & Felgenahuer, 1986). All aeglids are primarily aquatic and occur in lakes, streams, and caves, at depths of down to 320m in Chilean lakes (Jara, 1977), and at altitudes of up to ~3,500 m of altitude in northeastern Argentinean cordilleras (Bond-Buckup & Buckup, 1994).

Aeglids are the only anomuran family restricted to the Neotropical region of South America. Taxonomically, aeglids are included within the anomuran superfamily Galatheoidea, but there is some morphological evidence (e.g., gill structure and caparace sutures) and molecular data that suggest the Aeglidae should be in their own superfamily (Martin & Abele, 1986; Pérez-Losada et al., 2002b; Tudge & Scheltinga, 2002). From a conservation perspective, several of the known species are very restricted in distribution, and they and their habitats are considered threatened (Pérez-Losada et al., 2002a). From an ecological perspective, aeglids are unique because they are the only anomuran family entirely restricted to freshwater habitats.

The ecological role of Aegla species has not been assessed but their omnivorous diet includes periphyton, decaying allochtonous vegetable matter, aquatic invertebrates (Bahamonde & L, 1961; Burns, 1972; Lara & Moreno, 1995, Castro-Souza & Bond-Buckup, 2004), and fine particulate organic matter (Isler, 1988). Additionally, they constitute a relevant dietary item for the non-native rainbow trout (Oncorhynchus mykiss) in Chile and South Brazil and brown trout (Salmo trutta fario) in Chile (Burns, 1972; Arenas, 1978; Buckup, personal observation), and for the Chilean and Brazilian species of river otter (Medina, 1998).

The present Aeglidae belong to a single genus, Aegla Leach, 1820, consisting of 63 described species (Bond-Buckup & Buckup, 1994; Bond-Buckup, 2003); including, newly described species based on recent molecular phylogenetic analyses (Jara et al., 2003). By our count, there are at least six additional species waiting to be described. Of these species, 57 are found mainly in rivers, only two in lakes, and four in cave habitats.

Our Patagonia study focuses on the phylogeographic patterns of a few selected species for comparisons against one another and to compare to the other organisms in the study. These species include Aegla abtao, Aegla alacalufi, Aegla neuquensis, and Aegla riolimayana.

Related Articles:

Rudolph, E.H. and K. A. Crandall. 2005. A new species of burrowing crayfish Virilastacus rucapihuelensis (Crustacea, Decapoda, Parastacidae) from southern Chile. Proceedings of the Biological Society of Washington 118(4):765-776.

Porter, M. L., M. Perez-Losada, and K. A. Crandall. 2005. Model based multi-locus estimation of Decapod phylogeny and divergence times. Molecular Phylogenetics and Evolution 37:355-367.

Crandall, K. A. and J. Buhay. 2004. Genomic databases and the Tree of Life. Science 306:1144-1145.

Pearse, D. E., and K. A. Crandall. 2004. Beyond FST: Analysis of population genetic data for conservation. Conservation Genetics 5(5):585-602.

Pérez-Losada, M., G. Bond-Buckup, C. G. Jara, and K. A. Crandall. 2004. Molecular systematics and biogeography of the Southern South American freshwater "crabs" Aegla (Decapoda: Anomura: Aeglidae) using multiple heuristic tree search approaches. Systematic Biology 53(5):767-780.

Agapow, P.-M., O. R. P. Bininda-Emonds, K. A. Crandall, J. L. Gittleman, G. M. Mace, J. C. Marshall, and A. Purvis. 2004. The impact of species concept on biodiversity studies. Quarterly Review of Biology 79(2):161-179.

Jara, C. G., M. Pérez-Losada, and K. A. Crandall. 2003. Aegla occidentalis (Crustacea: Decapoda: Aeglidae), a new species of freshwater crab from the Nahuelbuta Coastal Range, Chile. Proceedings of the Biological Society of Washington 116(4):933-942.

Pérez-Losada, M., and K. A. Crandall. 2003. Can taxonomic richness be used as a surrogate for phylogenetic distinctness indices for ranking areas for conservation? Animal Biodiversity and Conservation 26:77-84.

Pérez-Losada, M., C. G. Jara, G. Bond-Buckup, M. L. Porter and K. A. Crandall. 2002. Anomuran phylogenetic relationships: on the taxonomic positioning of Aeglidae freshwater crabs. Journal of Crustacean Biology 22(3):670-676.

Pérez-Losada, M., C. G. Jara, G. Bond-Buckup and K. A. Crandall. 2002. Phylogenetic relationships maong the species of Aegla (Anomura: Aeglidae) freshwater crabs from Chile. Journal of Crustacean Biology 22(2):304-313.

Pérez-Losada, M., C. G. Jara, G. Bond-Buckup and K. A. Crandall. 2002. Conservation phylogenetics of Chilean freshwater crabs Aegla (Anomura, Aeglidae): Assigining priorities for aquatic habitat protection. Biological Conservation 105:345-353.

Further Information:

Copies of the related articles can be found at the Crandall Lab Publications page.