The effect of the Central Andes on the diversification of distinct lineages of South American rodents

The Andes in South America represent the longest continental mountain chain on Earth. Tectonic and climatic changes produced by the Andean uplift shaped the diversification histories of myriad organisms. What role the Andes played is dependent upon time and space. This research combines phylogenetics, genomics, population genetics, and biogeography at different taxonomical and temporal levels, to explore the diversification history of rodents distributed along the central Andes (i.e., from southern Peru to northern Argentina). Caviomorph and sigmodontine rodents, with very different colonization and radiation histories, represent the two main monophyletic lineages in the continent and were the focus of my research. The results of this dissertation provide further support to the notion that the effects of the Andes on the evolution and diversification of rodents vary according to the geological epoch and the predominant events occurring at the time (i.e., tectonic vs climate processes). For older groups inhabiting South America since at least the Eocene (e.g., the family Abrocomidae), the uplift of the Andes and the resulting changes in the landscape had a direct effect on their evolutionary history. On the contrary, processes occurring during the last 2 Ma were related to changes in climate that in turn promoted glaciation cycles in the cordilleras and the expansion and reduction in the size of paleo-lakes in the Altiplano. In this case, the population structure and phylogeographic patterns of Akodon albiventer and Calomys lepidus reveal very different responses to the same historical processes. Other findings include the need to rearrange species of Abrocomidae into new genera for their taxonomy to better reflect their systematics and the true diversity within the family, and the existence of three highly divergent clades within Abrocoma boliviensis that should be treated, at a minimum, as separate evolutionary significant units, emphasizing the urgent need to increase survey efforts and obtain demographic and ecological data to better inform any future conservation efforts.

Embargo status: Restricted until 06/2027. To request the author grant access, click on the PDF link to the left.