The transition to pleurocarpy: A phylogenetic analysis of the main diplolepidous lineages based on rbcL sequences and morphology

Hypotheses of character evolution require a phylogeny for polarization of t ransformations and optimization of state changes. Our goal is to provide a phylogenetic hypothesis for diplolepidous mosses to investigate the evoluti on of,morphological features associated with the transition to pleurocarpy. We performed cladistic analyses of morphological and molecular data sets f or exemplars of the main diplolepidous lineages. These analyses were design ed to sample families commonly included in the Leucodontales, Hookeriales, and Hypnales with some exemplars also from the Bryales. Diplolepidous taxa (Bryaceae, Splachnaceae, Orthotrichaceae, Macromitriaceae, and Hedwigiaceae ) were included as close outgroups, and Dicranum scoparium, Grimmia apocarp a, and Funaria hygrometrica were included as distant outgroups. We construc ted a molecular data set derived from sequences of the chloroplast rbcL gen e for 36 species, 22 of which were pleurocarp exemplars. In the molecular a nalysis, the bryalean pleurocarps were the sister group of acrocnrp exempla rs from the Bryales. However, in the analyses of combined morphological and rbcL data, the bryalean pleurocarps were the sister group of a clade that includes the 11 exemplars from the Leucodontales, Hypnales, and Hookeriales , thus pleurocarpy appeared monophyletic. Decay analyses suggested that the grouping of bryalean and hypnobryalean pleurocarps together was weak where as both the hypnobryalean and bryalean pleurocarp clades were individually robust. Present cladistic analyses provide an inferential basis for structu ral investigations of branching systems and the evolution of pleurocarpy in a phylogenetic context.