DOI: 10.5061/dryad.93p7f
title: Data from: Stasis and convergence characterize morphological evolution in eupolypod II ferns

description: Background and Aims: Patterns of morphological evolution at levels above
 family rank remain underexplored in the ferns. The present study seeks to
 address this gap through analysis of 79 morphological characters for 81
 taxa, including representatives of all ten families of eupolypod II ferns.
 Recent molecular phylogenetic studies demonstrate that the evolution of
 the large eupolypod II clade (which includes nearly one-third of extant
 fern species) features unexpected patterns. The traditional ‘athyrioid’
 ferns are scattered across the phylogeny despite their apparent
 morphological cohesiveness, and mixed among these seemingly conservative
 taxa are morphologically dissimilar groups that lack any obvious features
 uniting them with their relatives. Maximum-likelihood and
 maximum-parsimony character optimizations are used to determine characters
 that unite the seemingly disparate groups, and to test whether the
 polyphyly of the traditional athyrioid ferns is due to evolutionary stasis
 (symplesiomorphy) or convergent evolution. The major events in eupolypod
 II character evolution are reviewed, and character and character state
 concepts are reappraised, as a basis for further inquiries into fern
 morphology. Methods: Characters were scored from the literature, live
 plants and herbarium specimens, and optimized using maximum-parsimony and
 maximum-likelihood, onto a highly supported topology derived from
 maximum-likelihood and Bayesian analysis of molecular data. Phylogenetic
 signal of characters were tested for using randomization methods and
 fitdiscrete. Key Results: The majority of character state changes within
 the eupolypod II phylogeny occur at the family level or above. Relative
 branch lengths for the morphological data resemble those from molecular
 data and fit an ancient rapid radiation model (long branches subtended by
 very short backbone internodes), with few characters uniting the
 morphologically disparate clades. The traditional athyrioid ferns were
 circumscribed based upon a combination of symplesiomorphic and homoplastic
 characters. Petiole vasculature consisting of two bundles is ancestral for
 eupolypods II and a synapomorphy for eupolypods II under deltran
 optimization. Sori restricted to one side of the vein defines the recently
 recognized clade comprising Rhachidosoraceae through Aspleniaceae, and
 sori present on both sides of the vein is a synapomorphy for the
 Athyriaceae sensu stricto. The results indicate that a chromosome base
 number of x =41 is synapomorphic for all eupolypods, a clade that includes
 over two-thirds of extant fern species. Conclusions: The integrated
 approach synthesizes morphological studies with current phylogenetic
 hypotheses and provides explicit statements of character evolution in the
 eupolypod II fern families. Strong character support is found for
 previously recognized clades, whereas few characters support previously
 unrecognized clades. Sorus position appears to be less complicated than
 previously hypothesized, and linear sori restricted to one side of the
 vein support the clade comprising Aspleniaceae, Diplaziopsidaceae,
 Hemidictyaceae and Rachidosoraceae – a lineage only recently identified.
 Despite x =41 being a frequent number among extant species, to our
 knowledge it has not previously been demonstrated as the ancestral state.
 This is the first synapomorphy proposed for the eupolypod clade, a lineage
 comprising 67 % of extant fern species. This study provides some of the
 first hypotheses of character evolution at the family level and above in
 light of recent phylogenetic results, and promotes further study in an
 area that remains open for original observation.
description: eupolypodsII_character_matrixIncludes 79 discrete morphological characters scored for 81 taxa and one tree file depicting relationships of eupolypod II fernsfinal_matrix_Eu2_Aug_2013_Dryad.nex