The Laboratory of Evolution is part of the Animal Biology Department in the Biology Institute of the School of Sciences, Universidad de la República (Montevideo, Uruguay). Since its beginning in 1992, the laboratory has worked on diverse topics of evolution and systematic of vertebrates, with emphases on mammals. Whereas our studies commonly analyze molecular data, they normally are used to understand the biology of organisms, species and phylogenetic groups.
Cerro Ventana`s tucu-tucu.
Prov. of Santa Cruz, Argentina.
This long-term line of research focuses on tuco-tucos as a model for the study of diversification.
Tuco-tucos offer interesting opportunities to examine the processes of evolution for several reasons: a) they represent one of the most recent invasions of the subterranean niche, therefore offering a variety of levels of specialization; b) they are allied to octodontids, a group of fossorial rodents that include an independently derived, fully subterranean lineage: the coruro (Spalacopus); c) they have a rich fossil record that includes complete skeletons and burrows; d) they have diverse types of social structure (including the social tuco-tuco, C. sociabilis); and d) they are though to represent a case of recent and explosive speciation.
In collaboration with many colleagues and current and former students, I have been interested in examining processes of diversification at various levels of organization and with different approaches. Population genetic analyses have been used to examine the roles of strict isolation, gene flow, demographic history and natural selection in shaping geographical variation. Phylogenetic analyses have been exploited to understand the rate and tempo of tuco-tuco diversification, the identification of species groups and their biogeographical history, and evidence of neutral and adaptive change at the molecular level. Morphometric and morphological analyses have been used to examine both population-level and larger scale patterns of divergence (including both recent and fossil taxa).
Punta de Vacas hill, Santa Cruz.Collaborators: Guillermo D´Elía, Ulyses Pardiñas, Carolina Abud, Matías Feijoo.
This long-term project aims at understanding the current diversity and history of small mammals of the Patagonian region (including Tierra del Fuego) using systematic and population genetic tools. Extensive field work was carried out on 2005-2006 with support from the National Geographic Society, Committee for Research and Exploration (with CO-PIs: Guillermo D´Elía, Universidad de Concepción, Chile, and Ulyses Pardiñas, Centro Nacional Patagónico, Conicet, Puerto Madryn, Argentina). Standard skins and skeletons were prepared along chromosomal, parasite, and tissue preparations. Currently, DNA sequencing and morphological analyses are under way to determine patterns of variation and evidence of the history of populations and their response to historical climate change since the Pleistocene. Conceptually, the project was motivated by earlier work on the late Pleistocene history of mammals in western Amazonia and Western North America.
Lessa, E. P., J. A. Cook, & J. L. Patton. 2003. Genetic footprints of demographic expansion in North America, but not Amazonia, during the Late Quaternary. PNAS 100:10331-10334.
We have worked on sheep genetics since 1997 in association with SUL (Secretariado Uruguayo de la Lana). Our first project, funded by CSIC (Comisión Sectorial de Investigación Científica, Universidad de la República), was directed towards developing a system of relatedness determination using microsatellites and characterizing allelic frequencies of Uruguayan ovine flocks for those markers. In 1999, we started the study of the Booroola mutation (associated to prolificity) in Uruguay. The study had an initial stage based on microsatellites tightly linked to the gene of interest (which, by that time, had been mapped but not identified), and a more recent stage in which the diagnosis of the mutation and the number of copies in an individual can be obtained directly. The work continues as a service in support of field studies conducted by SUL.
Ongoing work involves collaboration with the laboratory of Alfredo Pereira in DINARA (Dirección Nacional de Recursos Acuáticos). In the case of the white croaker (Micropogonias furnieri), mitochondrial and microsatellite loci data suggest geographic subdivision populations in the Río de la Plata and the Atlantic Ocean are genetically differentiated. Currently, we are expanding our studies to additional coastal species of commercial interest such as king weakfish (Macrodon ancylodon), striped weakfish (Cynoscion guatucupa Cuvier, 1830) and Brazilian codling (Urophycis brasiliensis Kaup, 1858) using both microsatellite and mitochondrial markers. Conceptually, understanding genetic structure and its association with geographical and environmental diversity, history and current gene flow are similar for fishes and for other groups of organisms. Thus, the distinction between basic and applied research lays best in the use (immediate or putative) of results, rather than in their foundations or research methods.
We have conducted studies of marine mammals trying to understand how genetic variation is structured, both geographically and locally, especially in relation to social groups. Current and recent work has involved analysis of population genetic structure of the South American sea lion, Otaria flavescens (Matias Feijoo's master's thesis) and social and population structure analysis of the franciscana dolphin (Paula Costa's master's thesis). We want to establish the degree of genetic differentiation between Uruguayan and Patagonian sea lions using mitochondrial sequences and microsatellites, as a contribution to define management units and understand their biological connections. The second project used microsatellite frequencies to analyze the genetic diversity between Rio de la Plata and Atlantic Ocean populations and kinship relations of individuals within putative social groups.