Molecular analysis of a 11 700-year-old rodent midden from the Atacama Desert, Chile


  • Melanie Kuch, Nadin Rohland and Hendrik Poinar develop techniques of extracting DNA from previously untapped sources, and apply the data to answer questions of Pleistocene ecology, species identification and to test various phylogeographic models. Scott Steppan studies rodent phylogenetics with a focus on Muridae and is combining quantitative genetic and phylogenetic approaches to study multivariate evolution in Phyllotis. Claudio Lattore and Julio Betancourt specialize in the macro-analysis of fossil rodent middens from around the world in the attempt to reconstruct palaeoclimates and range shifts.

H. N. Poinar. Fax: + 49 (341) 9952 555; E-mail:


DNA was extracted from an 11 700-year-old rodent midden from the Atacama Desert, Chile and the chloroplast and animal mitochondrial DNA (mtDNA) gene sequences were analysed to investigate the floral environment surrounding the midden, and the identity of the midden agent. The plant sequences, together with the macroscopic identifications, suggest the presence of 13 plant families and three orders that no longer exist today at the midden locality, and thus point to a much more diverse and humid climate 11 700 years ago. The mtDNA sequences suggest the presence of at least four different vertebrates, which have been putatively identified as a camelid (vicuna), two rodents (Phyllotis and Abrocoma), and a cardinal bird (Passeriformes). To identify the midden agent, DNA was extracted from pooled faecal pellets, three small overlapping fragments of the mitochondrial cytochrome b gene were ampli-fied and multiple clones were sequenced. These results were analysed along with com-plete cytochrome b sequences for several modern Phyllotis species to place the midden sequence phylogenetically. The results identified the midden agent as belonging to an ancestral P. limatus. Today, P. limatus is not found at the midden locality but it can be found 100 km to the north, indicating at least a small range shift. The more extensive sampling of modern Phyllotis reinforces the suggestion that P. limatus is recently derived from a peripheral isolate.