The Utility of Nuclear ITS, aLEAFYHomolog Intron, and ChloroplastatpB-rbcLSpacer Region Data in Phylogenetic Analyses and Species Delimitation in Isoëtes

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Abstract
Despite its ancient origins, its worldwide distribution, and adaptation to diverse habitats, Isoëtes has a highly conserved morphology. This feature has made it difficult to resolve species and species relationships using morphological characters. In this paper, we report the utility of nucleotide sequences from the nuclear internal transcribed spacer (ITS) regions, chloroplast atpB/rbcL intergenic spacer region, and second intron of a LEAFY (LFY) homolog for identifying species relationships, delimiting basic diploid species, and determining hybrid origins. Variation in the ITS regions and atpB/rbcL spacer is most useful at the family level in Isoëtes and the LFY second intron is appropriate at the species and population level. The tree resulting from an analysis of the combined nuclear ITS and chloroplast atpB/rbcL spacer contains three major well supported clades (bootstrap ≥ 99%): an Old-World/California clade (I. abyssinica, I. longissima, I. velata, I. nuttallii, and I. orcuttii), an Asian/...