Phylogeography of the genus Podococcus (Palmae/Arecaceae) in Central African rain forests: Climate stability predicts unique genetic diversity A. Faye a,b,⇑ , V. Deblauwe a,b , C. Mariac a , D. Richard a , B. Sonké b , Y. Vigouroux a , T.L.P. Couvreur a,b,c a Institut de Recherche pour le Développement, UMR-DIADE, BP 64501, F-34394 Montpellier cedex 5, France b Université de Yaoundé I, Ecole Normale Supérieure, Département des Sciences Biologiques, Laboratoire de Botanique systématique et d’Ecologie, B.P. 047, Yaoundé, Cameroon c Naturalis Biodiversity Centre, Botany Section, Darwinweg 2, 2333 CR Leiden, The Netherlands article info Article history: Received 24 October 2015 Revised 8 August 2016 Accepted 9 August 2016 Available online 10 August 2016 Keywords: Phylogeography Africa Palms Plastome Refugia Coastal forests abstract The tropical rain forests of Central Africa contain high levels of species diversity. Paleovegetation or bio- diversity patterns suggested successive contraction/expansion phases on this rain forest cover during the last glacial maximum (LGM). Consequently, the hypothesis of the existence of refugia e.g. habitat stability that harbored populations during adverse climatic periods has been proposed. Understory species are tightly associated to forest cover and consequently are ideal markers of forest dynamics. Here, we used two central African rain forest understory species of the palm genus, Podococcus, to assess the role of past climate variation on their distribution and genetic diversity. Species distribution modeling in the present and at the LGM was used to estimate areas of climatic stability. Genetic diversity and phylogeography were estimated by sequencing near complete plastomes for over 120 individuals. Areas of climatic stabil- ity were mainly located in mountainous areas like the Monts de Cristal and Monts Doudou in Gabon, but also lowland coastal forests in southeast Cameroon and northeast Gabon. Genetic diversity analyses shows a clear North–South structure of genetic diversity within one species. This divide was estimated to have originated some 500,000 years ago. We show that, in Central Africa, high and unique genetic diversity is strongly correlated with inferred areas of climatic stability since the LGM. Our results further highlight the importance of coastal lowland rain forests in Central Africa as harboring not only high spe- cies diversity but also important high levels of unique genetic diversity. In the context of strong human pressure on coastal land use and destruction, such unique diversity hotspots need to be considered in future conservation planning. Ó 2016 Elsevier Inc. All rights reserved. 1. Introduction The tropical rain forests (TRF) of Central Africa represent the second largest continuous extent of this biome after the Amazon basin and contain high levels of species diversity and endemicity (Linder, 2001). Ancient climate change 33–3 million years ago, was shown to be an important driver of diversification in animals and plants (e.g. Couvreur et al., 2008; Couvreur, 2015; Faye et al., 2016; Menegon et al., 2014; Tolley et al., 2013; Voelker et al., 2010). The impact, however, of the last glacial maximum (LGM, 24 k – 12 k years ago) remains debated (Hardy et al., 2013). Our knowledge about the recent dynamics of Central African TRF has mainly been inferred from paleovegetation studies (Bonnefille, 2007; Maley and Brenac, 1998), biodiversity patterns (Diamond and Hamilton, 1980; Sosef, 1996) or past vegetation modeling (Cowling et al., 2008). Most of these studies suggested that African rain forests were affected by successive contraction/expansion events (Bonnefille, 2007) during the glacial cycles of the Pleis- tocene (in particular during the LGM). These repeated sequences of forest dynamics led to the hypothesis of forest refugia (Diamond and Hamilton, 1980; Maley, 1996; Sosef, 1994). Refugia are defined as geographical areas that operate on evolutionary time scales allowing viable populations of a species to persist throughout climatic oscillations. Because this definition is species-specific (Hewitt, 2000; Stewart et al., 2010), refugia refer to areas of species-specific habitat stability rather than to broadly defined climatically-stable regions (Ashcroft, 2010; Stewart et al., 2010). Maley (1996) identified several areas as potential refugia located along the West and Central African coasts and in the Congo Basin, mainly in montane regions (Fig. 1). These are recognized as the ‘‘traditional refugia” against which most data are compared to when discussing the existence of refugia in Africa (Anthony et al., 2007; Dauby et al., 2010; Droissart, 2009; Gomez et al., 2009). http://dx.doi.org/10.1016/j.ympev.2016.08.005 1055-7903/Ó 2016 Elsevier Inc. All rights reserved. ⇑ Corresponding author at: IRD Montpellier, UMR DIADE, Team DYNADIV, 911 avenue Agropolis, 34394 Montpellier cedex 5, France. E-mail address: adamafae@gmail.fr (A. Faye). Molecular Phylogenetics and Evolution 105 (2016) 126–138 Contents lists available at ScienceDirect Molecular Phylogenetics and Evolution journal homepage: www.elsevier.com/locate/ympev