Interglacial microrefugia and diversification of a cactus species complex: phylogeography and palaeodistributional reconstructions for Pilosocereus aurisetus and allies |
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Authors: | Isabel A S Bonatelli Manolo F Perez A Townsend Peterson Nigel P Taylor Daniela C Zappi Marlon C Machado Ingrid Koch Adriana H C Pires Evandro M Moraes |
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Institution: | 1. Departamento de Biologia, Universidade Federal de S?o Carlos, , 18052780 Sorocaba, S?o Paulo, Brazil;2. Biodiversity Institute, University of Kansas, , Lawrence, KS, 66045 USA;3. National Parks Board, Singapore Botanic Gardens, , Singapore, 259569 Singapore;4. Royal Botanic Gardens, , Kew, Richmond, Surrey, TW9 3AB UK;5. Gardens by the Bay, , Singapore, Singapore;6. Departamento de Ciências Biológicas, Universidade Estadual de Feira de Santana, , 44031‐460 Feira de Santana, Bahia, Brazil |
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Abstract: | The role of Pleistocene climate changes in promoting evolutionary diversification in global biota is well documented, but the great majority of data regarding this subject come from North America and Europe, which were greatly affected by glaciation. The effects of Pleistocene changes on cold‐ and/or dry‐adapted species in tropical areas where glaciers were not present remain sparsely investigated. Many such species are restricted to small areas surrounded by unfavourable habitats, which may represent potential interglacial microrefugia. Here, we analysed the phylogeographic structure and diversification history of seven cactus species in the Pilosocereus aurisetus complex that are restricted to rocky areas with high diversity and endemism within the Neotropical savannas of eastern South America. We combined palaeodistributional estimates with standard phylogeographic approaches based on two chloroplast DNA regions (trnT‐trnL and trnS‐trnG), exon 1 of the nuclear gene PhyC and 10 nuclear microsatellite loci. Our analyses revealed a phylogeographic history marked by multiple levels of distributional fragmentation, isolation leading to allopatric differentiation and secondary contact among divergent lineages within the complex. Diversification and demographic events appear to have been affected by the Quaternary climatic cycles as a result of isolation in multiple patches of xerophytic vegetation. These small patches presently harbouring P. aurisetus populations seem to operate as microrefugia, both at present and during Pleistocene interglacial periods; the role of such microrefugia should be explored and analysed in greater detail. |
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Keywords: | Cactaceae
campos rupestres
microrefugia Neotropical diversification palaeodistributional modelling
Pilosocereus
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