I am mainly interested on the systematics, phylogeography, and historical biography of neotropical taxa using mitochondrial and nuclear DNA sequence data. During the three years that I worked at the Smithsonian Tropical Research Institute I focused on these topics using spiny rats of the genus Proechimys and bees of the tribe Euglossini as model organisms. The work with Proechimys was focused on the Central American species P. Semispinosus, and served as my Bachelor thesis as well. The goal of this project was to study the phylogeographic structure of this cosmopolitan rodent in order to better understand its biogeographic history in Central America. I sequenced two mitochondrial (CytB and D-loop) DNA sequences from several individuals of this species from several localities throughout Panama and Costa Rica, and one locality in Colombia. This project was completely designed and developed by myself during my last years as an undergraduate student at University of Panama, with a lot of help from James Patton (U.C. Berkeley) and Eldredge Bermingham (STRI). My work with orchid bees (Apidae: Euglossini) was done in collaboration with David Roubik, Eldredge Bermingham, and Christopher Dick. The focus of this work the construction of a molecular phylogeny using mitochondrial (CO1) and nuclear (EF-1) DNA sequences from 38 species of euglossines and circa 200 individuals from Panama, Costa Rica, Mexico, Ecuador, French Guiana, Brazil, and Bolivia. The main objectives of this study were to perform a phylogenetic analysis of the tribe Euglossini, to examine the historical biogeography of the group based on species ranges, phylogenetic relationships, and history of the Neotropical landscape and to place the euglossine diversification into a temporal framework through the use of molecular clocks, and finally, to interpret our results in the context of the diversification of Stanhopeinae, a monophyletic subtribe of the Orchidaceae, whose 17 genera and 190 epiphytic species depend entirely on euglossine bees for pollination. I am also interested in several aspects of molecular evolution such as base composition biases, isochore evolution, and adaptive evolution. Currently my Master thesis at the University of Minnesota is focused on the construction of a molecular phylogeny of the subfamily Didelphinae using 2600 bp of nuclear (RAG1) DNA sequences for nearly all the genera of the subfamily. The main objective of this project is to build a well supported phylogeny of this group in order to support previous hypothesis of the intergeneric relationships of Didelphinae. A second theme is oriented toward the effect of bases composition biases in phylogenetic reconstruction, in particular biases toward G-C bases, which is documented to be related with isochore dynamic in mammals and which we think might be operating on several Didelphine taxa. Other interests include the use of Machine learning Algorithms such as Neural Networks for the analysis of DNA sequence Data and the use of GIS base layers with remote sensed data for the study of historical biogeography and species distribution of terrestrial taxa.