Original paper

Unraveling the taxonomic complexity of Eryngium L. (Apiaceae, Saniculoideae): Phylogenetic analysis of 11 non-coding cpDNA loci corroborates rapid radiations

Calviño, Carolina I.; Martínez, Susana G.; Downie, Stephen R.

Abstract

The evolution of the genus Eryngium L. combines a history of rapid radiations, long distance dispersals, and hybridizations. To corroborate whether the polytomies estimated in the phylogeny of Eryngium based on previous analyses of cpDNA trnQ-trnK and nrDNA ITS sequence data are due to rapid radiations, phylogenetic relationships of a subset of Eryngium species representing all major clades identified in our previous study were inferred using sequence data from 11 non-coding cpDNA regions (trnQ-rps16, rps16 intron, rps16-trnK, rpl32-trnL, ndhF-rpl32, psbJ-petA, 3'trnV-ndhC, trnfM-trnS, trnT-trnD, trnC-rpoB, and trnG-trnS). In total, 20 accessions representing seven informal and unranked groups of Eryngium subgenus Monocotyloidea and E. maritimum (E. subgenus Eryngium) were analyzed using maximum parsimony. Analysis of these 11 loci permitted an assessment of the relative utility of these non-coding regions in providing a more resolved and better supported phylogeny of the genus. The combined analysis of all cpDNA regions recovered the same informal groups previously recognized based on trnQ-trnK data alone: "New World s.str.", "North American monocotyledonous", "South American monocotyledonous", "Pacific", "Mexican", and "Eastern USA". The relationships among these groups, however, remained unresolved. Resolution in other portions of the tree and most bootstrap support values increased as a result of simultaneous analysis of all data. A cost/benefit examination indicated that maximum parsimony analysis of trnQ-trnK plus 3 regions (trnG-trnS, rpl32-trnL, and 3'trnV-ndhC) results in the same number of clades and similar bootstrap support values than in the combined analysis of all cpDNA regions. The present study continues to support that the major polytomies of Eryngium are due to rapid radiations, and the screening of 11 non-coding cpDNA regions allowed an efficient selection of the most informative loci and the minimum amount of regions necessary for increasing resolution and support within other portions of the phylogeny.

Keywords

apiaceaeeryngiumcpDNAphylogenyrapid radiation