DOI: 10.5061/dryad.38h06
title: Data from: Leaf form and photosynthetic physiology of Dryopteris species distributed along light gradients in eastern North America

description: 1.Despite the ubiquity of ferns and at least tacit recognition by
 botanists that their physiology is unique among land plants, most studies
 on fern physiology have focused on only a few, locally distributed,
 usually distantly related species. No previous study has attempted to
 examine physiological adaptations in a group of widespread taxa that are
 closely related and whose relationships are well understood. Here we
 report leaf form and physiological measures for such a group, the eleven
 eastern North American species of Dryopteris (Dryopteridaceae), and
 examine differences in these parameters for evidence of adaptation to
 light availability. 2.Economic theory predicts that species from sunnier
 habitats should have narrower, more steeply inclined leaves, lower
 specific leaf area, higher stomatal density, higher rates of maximum
 photosynthesis, respiration, and stomatal conductance, and require more
 light to saturate photosynthesis. Species should show adaptive cross-over
 in net carbon uptake per unit leaf mass, with a relative advantage by
 sun-associated species at high photon flux densities (PFDs) and by
 shade-associated species at low PFDs. 3.Field studies allow us to begin
 characterizing the range of native light environments occupied by members
 of this group, and to examine interspecific variation in several aspects
 of leaf form and photosynthetic light response for evidence of adaption to
 light availability. We also present a novel means for incorporating
 phylogeny in tests of correlated evolution in a reticulate lineage.
 4.Synthesis. Observed trends in physiology and morphology generally agree
 with qualitative predictions, but are often not statistically significant.
 We found no support for adaptive cross-over in mass-based carbon uptake,
 and thus for light availability being the most important variable driving
 morphological and physiological adaptation in these ferns. We propose that
 hydraulic factors related to water balance may have played a larger role
 in determining their morphological and physiological variation.
 Allopolyploid hybrids did not show transgression in any physiological
 parameter that may have allowed them to coexist regionally with their
 parents. The results of our phylogenetically-structured analyses highlight
 the importance of incorporating phylogeny into comparative studies,
 particularly when hybrid or polyploid taxa are present.
description: Physiological and
 morphological measurements of Dryopteris fernsThis Excel file contains
 data collected in the field for eleven species of Dryopteris ferns in
 eastern North America. Physiological and morphological data include canopy
 transmittance, gas exchange parameters (Amax, Amax-mass, R, Rmass, k, LCP,
 ICP, gs), specific leaf area (SLA), stomatal densities, frond and plant
 narrowness (based on length or height and width measurements), and angles
 of frond inclination. Data for individual plants are given, along with
 means and standard errors reported in the manuscript.SessaGivnishFEdata.xlsx