Radiation of the Australian Salicornioideae (Chenopodiaceae)—based on evidence from nuclear and chloroplast DNA sequences

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Abstract
In phylogenetic analyses of nuclear ITS and chloroplasttrnLDNA sequences, the mostly endemic Australian genera;Halosarcia,Pachycornia,Sclerostegia,Tecticornia, andTegicorniaof the subfamily Salicornioideae (Chenopodiaceae) together form a monophyletic group, congruent with the hypothesis that they evolved from a common ancestor. However, limited genetic differentiation evident in both nrDNA and cpDNA sequences among these taxa suggests a possible rapid radiation. Based on fossil pollen records and climatic models of other authors, it is hypothesized that the expansion of the Australian endemic Salicornioideae most likely occurred during the Late Miocene to Pliocene, when increasing aridity caused the formation of extensive salt lakes along endorheic paleodrainage channels. Moreover, AustralianSarcocorniarepresentatives were supported as monophyletic, nested within a paraphyleticSarcocorniaclade that also comprised EuropeanSalicorniain the ITS analysis. This suggests thatSarcocorniaarrived in Australia subsequent to the ancestor of the Australian endemic genera most likely via long‐distance dispersal.
Funding Information
  • Division of Arctic Sciences
  • Minerals and Energy Research Institute of Western Australia
  • Kalgoorlie Consolidated Gold Mines