title: Phylogeny of Selaginellaceae: There is value in morphology after all!
abstract: OBJECTIVE
  The cosmopolitan lycophyte family Selaginellaceae, dating back to the Late Devonian-Early Carboniferous, is notorious for its many species with a seemingly undifferentiated gross morphology. This morphological stasis has for a long time hampered our understanding of the evolutionary history of the single genus Selaginella. Here we present a large-scale phylogenetic analysis of Selaginella, and based on the resulting phylogeny, we discuss morphological evolution in the group.
  
  
  METHODS
  We sampled about one-third of the approximately 750 recognized Selaginella species. Evolutionary relationships were inferred from both chloroplast (rbcL) and single-copy nuclear gene data (pgiC and SQD1) using a Bayesian inference approach. The morphology of the group was studied and important features mapped onto the phylogeny.
  
  
  RESULTS
  We present an overall well-supported phylogeny of Selaginella, and the phylogenetic positions of some previously problematic taxa (i.e., S. sinensis and allies) are now resolved with strong support. We show that even though the evolution of most morphological characters involves reversals and/or parallelisms, several characters are phylogenetically informative. Seven major clades are identified, which each can be uniquely diagnosed by a suite of morphological features. There is value in morphology after all!
  
  
  CONCLUSIONS
  Our hypothesis of the evolutionary relationships of Selaginella is well founded based on DNA sequence data, as well as morphology, and is in line with previous findings. It will serve as a firm basis for further studies on Selaginella with respect to, e.g., the poorly known alpha taxonomy, as well as evolutionary questions such as historical biogeographic reconstructions.
authors.affiliation: Systematic Biology, Department of Organismal Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden stina.weststrand@ebc.uu.se stinaweststrand@gmail.com.
authors.forename: Stina
authors.initials: S
authors.lastname: Weststrand
authors.affiliation: Systematic Biology, Department of Organismal Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden.
authors.forename: Petra
authors.initials: P
authors.lastname: Korall
mesh_terms: D001499:Bayes Theorem; D005075:Biological Evolution; D002467:Cell Nucleus / Q000235:genetics; D002736:Chloroplasts / Q000235:genetics; D032461:Chromosomes, Plant / Q000235:genetics*; D014644:Genetic Variation; D010802:Phylogeny; D018515:Plant Leaves / Q000033:anatomy & histology / Q000145:classification / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics; D032503:Selaginellaceae / Q000033:anatomy & histology / Q000145:classification* / Q000235:genetics*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
chemical_list: D010940:Plant Proteins
keywords: SQD1; Selaginella; Selaginellaceae; lycophytes; morphology; pgiC; phylogeny; rbcL