Advertisement

Evidence for nonallopatric speciation among closely related sympatric Heliotropium species in the Atacama Desert

Authors

  • Federico Luebert,

    Corresponding author
    1. Freie Universität Berlin, Institut für Biologie – Botanik, Berlin, Germany
    2. Departamento de Silvicultura, Facultad de Ciencias Forestales y Conservación de la Naturaleza, Universidad de Chile, Santiago, Chile
    Current affiliation:
    1. Nees-Institut für Biodiversität der Pflanzen, Rheinische Friedrich-Wilhelms-Universität, Bonn, Germany
    • Correspondence

      Federico Luebert, Nees-Institut für Biodiversität der Pflanzen, Rheinische Friedrich-Wilhelms-Universität, Meckenheimer Allee 170, D-53115, Bonn, Germany. Tel: +49-228-737025; Fax: +49-228-733120;

      E-mail: fluebert@uni-bonn.de

    Search for more papers by this author
  • Pit Jacobs,

    1. Freie Universität Berlin, Institut für Biologie – Botanik, Berlin, Germany
    Search for more papers by this author
  • Hartmut H. Hilger,

    1. Freie Universität Berlin, Institut für Biologie – Botanik, Berlin, Germany
    Search for more papers by this author
  • Ludo A. H. Muller

    1. Freie Universität Berlin, Institut für Biologie – Botanik, Berlin, Germany
    Search for more papers by this author

Abstract

The genetic structure of populations of closely related, sympatric species may hold the signature of the geographical mode of the speciation process. In fully allopatric speciation, it is expected that genetic differentiation between species is homogeneously distributed across the genome. In nonallopatric speciation, the genomes may remain undifferentiated to a large extent. In this article, we analyzed the genetic structure of five sympatric species from the plant genus Heliotropium in the Atacama Desert. We used amplified fragment length polymorphisms (AFLPs) to characterize the genetic structure of these species and evaluate their genetic differentiation as well as the number of loci subject to positive selection using divergence outlier analysis (DOA). The five species form distinguishable groups in the genetic space, with zones of overlap, indicating that they are possibly not completely isolated. Among-species differentiation accounts for 35% of the total genetic differentiation (FST = 0.35), and FST between species pairs is positively correlated with phylogenetic distance. DOA suggests that few loci are subject to positive selection, which is in line with a scenario of nonallopatric speciation. These results support the idea that sympatric species of Heliotropium sect. Cochranea are under an ongoing speciation process, characterized by a fluctuation of population ranges in response to pulses of arid and humid periods during Quaternary times.

Ancillary