A large historical refugium explains spatial patterns of genetic diversity in a Neotropical savanna tree species
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2017
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Background and Aims The relative role of Pleistocene climate changes in driving the geographic distribution
and genetic diversity of South American species is not well known, especially from open biomes such as the
Cerrado, the most diverse tropical savanna, encompassing high levels of endemism. Here the effects of Quaternary
climatic changes on demographic history, distribution dynamics and genetic diversity of Dimorphandra mollis, an
endemic tree species widely distributed in the Cerrado, were investigated.
Methods A total of 38 populations covering most of the distribution of D. mollis were analysed using internal
transcribed spacer (ITS) sequences and nuclear microsatellite variation [simple sequence repeats (SSRs)]. The
framework incorporated statistical phylogeography, coalescent analyses and ecological niche modelling (ENM).
Key Results Different signatures of Quaternary climatic changes were found for ITS sequences and SSRs corresponding
to different time slices. Coalescent analyses revealed large and constant effective population sizes, with
high historical connectivity among the populations for ITS sequences and low effective population sizes and gene
flow with recent population retraction for SSRs. ENMs indicated a slight geographical range retraction during the
Last Glacial Maximum. A large historical refugium across central Brazil was predicted. Spatially explicit analyses
showed a spatial cline pattern in genetic diversity related to the paleodistribution of D. mollis and to the centre of its
historical refugium.
Conclusions The complex genetic patterns found in D. mollis are the result of a slight geographical range
retraction during the Last Glacial Maximum followed by population expansion to the east and south from a large
refugium in the central part of the Cerrado. This historical refugium is coincident with an area predicted to be
climatically stable under future climate scenarios. The identified refugium should be given high priority in conservation
polices to safeguard the evolutionary potential of the species under predicted future climatic changes.
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Cerrado, Refugium, Climatic changes, Coalescent analysis, Demographic history, Phylogeography, Dimorphandra mollis, Neotropical savanna, Ecological niche modelling, Genetic diversity
Citação
SOUZA, Helena Augusta Viana e; COLLEVATTI, Rosane Garcia; LIMA-RIBEIRO, Matheus S.; LEMOS-FILHO, José Pires de; LOVATO, Maria Bernadete. A large historical refugium explains spatial patterns of genetic diversity in a Neotropical savanna tree species. Annals of Botany, Oxford, v. 119, n. 2, p. 239-252, 2017. DOI: 10.1093/aob/mcw096. Epub 2016 Jun 16. Disponível em: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5321056/. Acesso em: 22 mar. 2023.