CONICET | Buscador de Institutos y Recursos Humanos

Species delimitation is a topic of continuous revision and debate. The objective of this thesis was to examine the taxonomy, systematics and evolution of Eligmodontia using chromosome, morphological and molecular analyses. Four well-differentiated species were identified: E. morgani, E. typus, E. puerulus and E. hirtipes, whereas E. moreni and E. bolsonensis exhibited little differences in some of the analyses. Single chromosome complements were recorded in E. moreni, E. typus, E. bolsonensis, and variable karyotypes in E. morgani and E. puerulus. Four species, excepting E. typus and E. bolsonensis, are separated morphologically. At molecular level (cytochrome-b), species presented intra-specific and inter-specific distances similar to those of other rodents, although E. puerulus has high variability and some individuals are non-distinguishable from E. moreni. The Eligmodontia species showed a strong correlation between the chromosomal differences (from conventional karyotype) and morphology. There was also positive correlation between morphological and molecular divergence, but this correlation was lost when E. moreni is compared with specimens of E. puerulus from Catamarca. In the latter case is observed a lack of differentiation at molecular level but high morphological differentiation. In this genus, three clades were identified (cytochrome-b), one composed of E. hirtipes + E. puerulus - E. moreni. These species have a north-central distribution and karyotypes with high FN. One of the other two clades is composed of E. typus and E. bolsonensis and the other one of E. morgani exclusively. These species have a south-central distribution and low FN. Diversification in Eligmodontia is linked to Andean orogeny and the most recent cladogenesis are associated with later mountain uplifts. (Partially supported by CONICET, PIP 5944, and Agencia, PICT 25778)