Abstract

BackgroundDuring past glacial periods, many species of forest-dwelling animals experienced range contractions. In contrast, species living outside such moist habitats appear to have reacted to Quaternary changes in different ways. The Atlantic Forest represents an excellent opportunity to test phylogeographic hypotheses, because it has a wide range of vegetation types, including unforested habitats covered predominantly by herbaceous and shrubby plants, which are strongly influenced by the harsh environment with strong wind and high insolation. Here, we investigated the distribution of genetic diversity in the endemic sand dune ant Mycetophylax simplex across its known range along the Brazilian coast, with the aim of contributing to the understanding of alternative phylogeographic patterns. We used partial sequences of the mitochondrial gene cytochrome oxidase I and nuclear gene wingless from 108 specimens and 51 specimens, respectively, to assess the phylogeography and demographic history of this species. To achieve this we performed different methods of phylogenetic and standard population genetic analyses.ResultsThe observed genetic diversity distribution and historical demographic profile suggests that the history of M. simplex does not match the scenario suggested for other Atlantic Forest species. Instead, it underwent demographic changes and range expansions during glacial periods. Our results show that M. simplex presents a shallow phylogeographic structure with isolation by distance among the studied populations, living in an almost panmictic population. Our coalescence approach indicates that the species maintained a stable population size until roughly 75,000 years ago, when it underwent a gradual demographic expansion that were coincident with the low sea-level during the Quaternary. Such demographic events were likely triggered by the expansion of the shorelines during the lowering of the sea level.ConclusionsOur data suggest that over evolutionary time M. simplex did not undergo dramatic range fragmentation, but rather it likely persisted in largely interconnected populations. Furthermore, we add an important framework about how both glacial and interglacial events could positively affect the distribution and diversification of species. The growing number of contrasting phylogeographic patterns within and among species and regions have shown that Quaternary events influenced the distribution of species in more ways than first supposed.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-015-0383-4) contains supplementary material, which is available to authorized users.

Highlights

  • IntroductionMany species of forest-dwelling animals experienced range contractions

  • During past glacial periods, many species of forest-dwelling animals experienced range contractions

  • Phylogenetic relationships and structure We aligned a total of 108 sequences of the gene cytochrome oxidase subunit I (COI)

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Summary

Introduction

Many species of forest-dwelling animals experienced range contractions. Climate change affected the landscape of continental areas and the sea level, which in turn shaped coastal landscapes by forming land bridges, islands, sand coastal plains, as well as connecting and separating areas [1, 2] All these climatelinked processes may have influenced the evolutionary history of the species, especially those inhabiting coastal areas [3, 4]. Less is known about these phenomena in the Southern hemisphere, where the glacial refugia hypothesis only recently has been formally evaluated [10, 11] It is presently the most frequently suggested mechanism for the current distribution of species diversity in the Brazilian Atlantic Forest (AF), the second largest Neotropical forest after the Amazon rainforest

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