História Evolutiva de Pequenos Mamíferos em Paleovárzeas da Bacia Amazônica e Variação Genética em Unidades de Conservação do Rio Solimões

Abstract

Notes about Amazon rainforest being composed by several distinct biogeographic units are reported since the first studies about biodiversity. Alongside the strictly allopatric standards, such as those found between endemic areas, different genetic patterns can be found according to the complexity of the landscape and organisms analyzed. Historical events that provided new environments fit to colonization have their influence on genetic and ecological diversity are poorly known. Várzea and paleovárzea forests potentially harbour younger animal lineages within the Amazonian lowlands, colonized as new exploitable niches emerged during their establishment. We investigate the evolutionary history of small mammals in Upper-Middle Solimões’ paleovárzeas, aiming to understand the importance of regional historical environmental processes in West Amazonian megadiversity. We found high genetic diversity among small mammals in paleovárzeas and other adjacent ecoregions. This diversity is related to paleoclimatic events from the Pleistocene. Lineages currently occupying the paleovárzeas originated from lineages that expanded from surrounding highlands. Genetic signatures of demographic events in the small mammals lineages refer mainly to periods of low temperatures in the late Pleistocene and the beginning of Holocene, which potentially allowed colonization of new areas on the lowlands during drier periods, from when they began to diversify independently in the region today known as Paleovárzeas.