Get access

Probing the Monophyly of the Sphaeropleales (Chlorophyceae) Using Data From Five Genes

Authors

  • Nicholas P. Tippery,

    1. Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, USA
    Current affiliation:
    1. Department of Biological Sciences, University of Wisconsin—Whitewater, Whitewater, Wisconsin, USA
    Search for more papers by this author
  • Karolina Fučíková,

    1. Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, USA
    Search for more papers by this author
  • Paul O. Lewis,

    1. Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, USA
    Search for more papers by this author
  • Louise A. Lewis

    Corresponding author
    • Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, USA
    Search for more papers by this author

Author for correspondence: e-mail louise.lewis@uconn.edu.

Abstract

Molecular phylogenetic analyses have had a major impact on the classification of the green algal class Chlorophyceae, corroborating some previous evolutionary hypotheses, but primarily promoting new interpretations of morphological evolution. One set of morphological traits that feature prominently in green algal systematics is the absolute orientation of the flagellar apparatus in motile cells, which correlates strongly with taxonomic classes and orders. The order Sphaeropleales includes diverse green algae sharing the directly opposite (DO) flagellar apparatus orientation of their biflagellate motile cells. However, algae across sphaeroplealean families differ in specific components of the DO flagellar apparatus, and molecular phylogenetic studies often have failed to provide strong support for the monophyly of the order. To test the monophyly of Sphaeropleales and of taxa with the DO flagellar apparatus, we conducted a molecular phylogenetic study of 16 accessions representing all known families and diverse affiliated lineages within the order, with data from four plastid genes (psaA, psaB, psbC, rbcL) and one nuclear ribosomal gene (18S). Although single-gene analyses varied in topology and support values, analysis of combined data strongly supported a monophyletic Sphaeropleales. Our results also corroborated previous phylogenetic hypotheses that were based on chloroplast genome data from relatively few taxa. Specifically, our data resolved Volvocales, algae possessing predominantly biflagellate motile cells with clockwise (CW) flagellar orientation, as the monophyletic sister lineage to Sphaeropleales, and an alliance of Chaetopeltidales, Chaetophorales, and Oedogoniales, orders having multiflagellate motile cells with distinct flagellar orientations involving the DO and CW forms.

Get access to the full text of this article

Ancillary