title: The impact of multiple biogeographic barriers and hybridization on species-level differentiation.
abstract: OBJECTIVE
  The glacial cycles of the Quaternary did not impact Australia in the same way as Europe and North America. Here we investigate the history of population isolation, species differentiation, and hybridization in the southeastern Australian landscape, using five species of Lomatia (Proteaceae). We use a chloroplast DNA phylogeography to assess chloroplast haplotype (chlorotype) sharing among these species and whether species with shared distributions have been affected by shared biogeographic barriers. •
  
  
  METHODS
  We used six chloroplast DNA simple sequence repeats (cpSSR) across five species of Lomatia, sampled across their entire distributional range in southeastern Australia. Resulting size data were combined, presented as a network, and visualized on a map. Biogeographical barriers were tested using AMOVA. To explore hypotheses of chlorotype origin, we converted the network into a cladogram and reconciled with all possible species trees using parsimony-based tree mapping. •
  
  
  RESULTS
  Some chlorotypes were shared across multiple species of Lomatia in the study, including between morphologically differentiated species. Chlorotypes were either widespread in distribution or geographically restricted to specific regions. Biogeographical structure was identified across the range of Lomatia. The most parsimonious reconciled tree incorporated horizontal transfer of chlorotypes. •
  
  
  CONCLUSIONS
  Lomatia shows evidence of both incomplete lineage sorting and extensive hybridization between co-occurring species. Although the species in the study appear to have responded to a number of biogeographic barriers to varying degrees, our findings identified the Hunter River Valley as the most important long-term biogeographic barrier for the genus in southeastern Australia.
authors.affiliation: Evolution, Ecology and Genetics, School of Biology, The Australian National University, Building 116 Daley Road, Canberra, ACT 0200, Australia. Melita.Milner@anu.edu.au
authors.forename: Melita L
authors.initials: ML
authors.lastname: Milner
authors.forename: Maurizio
authors.initials: M
authors.lastname: Rossetto
authors.forename: Michael D
authors.initials: MD
authors.lastname: Crisp
authors.forename: Peter H
authors.initials: PH
authors.lastname: Weston
mesh_terms: D001315:Australia; D018742:DNA, Chloroplast / Q000235:genetics*; D049810:Genetic Speciation; D006239:Haplotypes; D006824:Hybridization, Genetic; D018895:Microsatellite Repeats; D008969:Molecular Sequence Data; D010802:Phylogeny; D058974:Phylogeography; D016133:Polymerase Chain Reaction; D039105:Proteaceae / Q000033:anatomy & histology / Q000145:classification / Q000235:genetics* / Q000502:physiology; D017422:Sequence Analysis, DNA; D017385:Sequence Homology
chemical_list: D018742:DNA, Chloroplast