Untangling generic limits in Azorella, Laretia, and Mulinum (Apiaceae: Azorelloideae): Insights from phylogenetics and biogeography

• Published in: TAXON
• Main Authors: Nicolas, Antoine N., Plunkett, Gregory M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2012
• Subjects: Antarctic; Austral; New Zealand; Patagonia; Antarc*
• Online Access: http://dx.doi.org/10.1002/tax.614008; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Ftax.614008; https://onlinelibrary.wiley.com/doi/pdf/10.1002/tax.614008

Abstract The taxonomic histories and generic delimitations of the Andean–Subantarctic genera Azorella, Laretia, and Mulinum are among the most complex in Apiaceae subfam. Azorelloideae. To understand the evolutionary underpinnings of this complexity, we reconstructed the phylogenetic and biogeographic relationships of these genera, using for the first time a sampling strategy that includes all of their recognized species as well as representatives from the related genera Huanaca, Schizeilema, and Stilbocarpa. Sequences from the plastid rpl16 intron and trnD–trnT region were generated and phylogenies based on maximum likelihood, parsimony, and Bayesian inference were compared. The resulting phylogenies show many areas of disagreement with the current taxonomic circumscription of the genera. Four genera (Azorella, Mulinum, Huanaca, Schizeilema) are not monophyletic, and a fifth, Laretia, is embedded in one of the Azorella subclades. Each of the two large clades, informally named the “Mulinum clade” and the “Schizeilema clade”, include species currently placed in Azorella. The “Mulinum clade” is further divided into six subclades, which collectively include 23 of 26 species of Azorella, the monotypic Laretia and all species of Mulinum. Biogeographic reconstructions, conducted using RASP, suggest that the group most likely has an Austral–Antarctic origin, with subantarctic South America as the ancestral area of the ingroup. The “Mulinum clade” and the “Schizeilema clade” appear to have followed opposite dispersal routes out of subantarctic South America either across the Subantarctics into New Zealand and Australia (“Schizeilema clade”), or into Patagonia and then to the upper Andes (“Mulinum clade”).