Biogeography and evolution of seeder and resprouter forms of Erica coccinea (Ericaceae) in the fire-prone Cape fynbos

The genus Erica represents the epitome of plant biodiversity in the South African Cape fynbos with over 700 species. This genus is composed of seeder and resprouter species, but both species diversity and endemism are strongly linked to the seeder habit and concentrated in the southwestern Cape Floristic Region (CFR). Erica coccinea is a relatively abundant and widespread fynbos species whose most remarkable morphological feature is the existence of distinct seeder and resprouter forms, frequently—but not always—in disjunct populations. Both higher within-population genetic diversity and among-population differentiation have been found in seeders, most likely as a consequence of the shorter generation times and faster population turnovers. Resprouters, despite being less diverse, are suspected to be ancestral. However, no solid evidence has yet been provided for the ancestrality of the resprouter form, or for the demographic processes that have determined the current distribution of genetic diversity in both regeneration forms. Here, we used microsatellites and sequences of the nuclear ribosomal internal transcribed spacers to describe the phylogeographic structure of seeder and resprouter E. coccinea populations and provide good evidence for the ancestral status of the resprouter form and the comparatively high rates of molecular evolution in derived seeder populations. We also reveal that mixed populations, where both seeder and resprouter individuals co-occur, were originated by secondary contacts. This study highlights the role of fire in driving accelerated diversification in seeder lineages of highly speciose CFR fynbos taxa.FO strongly thanks the Spanish Ministerio de Educación (travel Grant PR2010-0365) and the UCA Plan Propio de Investigación for providing travelling bursaries to do fieldwork. KBB acknowledges a PhD scholarship (FPI, BES-2009-015443) of the Spanish Ministry of Science and Innovation (MICINN). MH acknowledges a Ramón y Cajal fellowship (RYC2009-04537) from the Spanish Ministry of Science and Education (MICINN), and funding from the Research Council of Norway (203822/E40) and the Spanish Ministry of Economy and Competitiveness (CGL2012-40129-C02-02). SCGM and MH acknowledge the support of Marie Curie Intra European Fellowships within the 7th European Community Framework Programme (FP7-PEOPLE-2012-IEF, project nos. 328146 and 329088, respectively). JGS-M acknowledges a Ramón y Cajal fellowship (RYC2009-05164) from MICINN.Peer Reviewe