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Abstract A molecular phylogenetic analysis of the Andean genus Tarasa (Malvaceae) and related genera yielded unexpected results regarding generic boundaries, the origins of polyploidy, and the morphological attributes of the polyploid taxa. The polyploid species of Tarasa are particularly unusual because they have life histories and floral morphologies that contradict two traditional polyploid dogmas: they are annuals and have smaller floral features (including pollen) than the diploid species. Typically, polyploids are perennial and larger than their parents. Nuclear (ITS1, 5.8S, and ITS2) and chloroplast (psbA-trnH and trnT-trnL spacers, matK-3′ trnK intron) sequence data were used to reconstruct independent phylogenies to test the monophyly of the genus, determine its sister group(s), and investigate the origin of the polyploid species. Neither the nuclear nor the chloroplast phylogeny supports monophyly of Tarasa as currently circumscribed. The high Andean genus Nototriche, the North/South American disjunct genus Sphaeralcea, and Malacothamnus chilensis are placed within the Tarasa clade. The polyploid species of Tarasa are not monophyletic and thus have been generated multiple times. These findings suggest that the unusual morphological features of the tetraploids are the result of convergent evolution and not shared ancestry.
Tate et al. (Wed,) studied this question.