Phylogenetic Analysis of Ophioglossaceae Utilizing Low-Copy, Nuclear Genes

Indianapolis, IN

The fern family Ophioglossaceae is relatively small, with ten genera and around 112 species currently recognized. The family is known for its long, independent evolutionary trajectory resulting in significant morphological differences from other living ferns. Moreover, the family is believed to be descendants of Paleozoic ferns making them one of most ancient, primitive group of plants lineages extant today. In comparison to other ferns the members of Ophioglossaceae have relatively simple morphology with few stable characters on which to build robust classifications. Chloroplast DNA phylogenies of the family have supported the monophyly of most genera, and established hypotheses of evolutionary relationships within the family. Here we used a representative multicontinental sample set across the family to assess generic relationships. We amplified, cloned, and sequenced a transducin-like, low-copy, nuclear gene for 27 accessions representing 24 species in Ophioglossaceae including an outgroup. The nuclear region amplified was ~650 bp. We compared the resulting nuclear parsimony and likelihood phylogeny to published chloroplast DNA-based phylogenies. The nuclear and chloroplast DNA phylogenies supported the monophyly of a ‘botrychioid’ lineage composed of Botrychium s.s., Sceptridium, Japanobotrychium, and Botrypus. However, all three phylogenies differed in the placement of the earliest diverging lineages (i.e., Ophioglossum s.s., Ophioderma, Chieroglossa, Mankyua, and Helminthostachys). All genera except Ophioglossum s.s. and Botrypus were supported as monophyletic groups.