Abstract
BackgroundSeveral macroevolutionary hypotheses propose a synchrony between climatic changes and variations in the structure of faunal communities. Some of them focus on the importance of the species ecological specialization because of its effects on evolutionary processes and the resultant patterns. Particularly, Vrba’s turnover pulse hypothesis and resource-use hypothesis revolve around the importance of biome inhabitation. In order to test these hypotheses, we used the Biomic Specialization Index, which is based on the number of biomes occupied by each species, and evaluated the changes in the relative importance of generalist and specialist rodents in more than forty fossil sites from the Iberian Plio-Pleistocene.ResultsOur results indicate that there was a decrease in the specialization degree of rodent faunas during the Pliocene due to the global cooling that triggered the onset of the glacial events of the Cenozoic (around 2.75 Ma). The subsequent faunal transition after this critical paleoenvironmental event was characterized by an increase of specialization related to the adaptation to the new environmental conditions, which was mainly associated with the Pleistocene radiation of Arvicolinae (voles).ConclusionsThe pattern of faunal turnover is correlated with the development of the modern glaciations in the Northern Hemisphere around 2.75 Ma, and represents a reorganization of the rodent communities, as suggested by the turnover pulse hypothesis. Our data also support the resource-use hypothesis, which presumes the role of the degree of specialization in resources specifically related to particular biomes as a driver of differential speciation and extinction rates. These results stress the intimate connection between ecological and evolutionary changes.
Highlights
Several macroevolutionary hypotheses propose a synchrony between climatic changes and variations in the structure of faunal communities
Through the time span considered here, our results show the existence of two opposed patterns with an inflection point coincident with the onset of the Pleistocene glaciations
This is to say; during the Pliocene there was a transition from faunas with a higher prevalence of specialist species to faunas where biome generalists were predominant
Summary
Several macroevolutionary hypotheses propose a synchrony between climatic changes and variations in the structure of faunal communities. Vrba [12,13] is one of the best known of such evolutionary models This theory comprises a set of hypotheses showing the influence of global climatic shifts and the subsequent environmental changes on the turnover of species assemblages as a result of the drifting of geographic distributions, lineage originations and extinctions. The different conditions imposed by the ecological characteristics of species, and especially the biomes that they inhabit, have an effect on the macroevolutionary patterns that are observed through time and space [7,14,15,16,17]. Stochomys longicaudatus (Murinae, Rodentia) has an omnivore diet [22], but it is restricted to the equatorial rainforest of Central Africa [23]
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