Journal of Molecular Evolution

, Volume 46, Issue 2, pp 188–201

Rapid Diversification of Marine Picophytoplankton with Dissimilar Light-Harvesting Structures Inferred from Sequences of Prochlorococcus and Synechococcus (Cyanobacteria)

  • Ena  Urbach
  • David J.  Scanlan
  • Daniel L.  Distel
  • John B.  Waterbury
  • Sallie W.  Chisholm

DOI: 10.1007/PL00006294

Cite this article as:
Urbach, E., Scanlan, D., Distel, D. et al. J Mol Evol (1998) 46: 188. doi:10.1007/PL00006294

Abstract.

Cultured isolates of the unicellular planktonic cyanobacteria Prochlorococcus and marine Synechococcus belong to a single marine picophytoplankton clade. Within this clade, two deeply branching lineages of Prochlorococcus, two lineages of marine A Synechococcus and one lineage of marine B Synechococcus exhibit closely spaced divergence points with low bootstrap support. This pattern is consistent with a near-simultaneous diversification of marine lineages with divinyl chlorophyll b and phycobilisomes as photosynthetic antennae. Inferences from 16S ribosomal RNA sequences including data for 18 marine picophytoplankton clade members were congruent with results of psbB and petB and D sequence analyses focusing on five strains of Prochlorococcus and one strain of marine A Synechococcus. Third codon position and intergenic region nucleotide frequencies vary widely among members of the marine picophytoplankton group, suggesting that substitution biases differ among the lineages. Nonetheless, standard phylogenetic methods and newer algorithms insensitive to such biases did not recover different branching patterns within the group, and failed to cluster Prochlorococcus with chloroplasts or other chlorophyll b-containing prokaryotes. Prochlorococcus isolated from surface waters of stratified, oligotrophic ocean provinces predominate in a lineage exhibiting low G + C nucleotide frequencies at highly variable positions.

Key words:Prochlorococcus—Synechococcus— Cyanobacteria — Picophytoplankton — Photosynthetic picoplankton — Prochlorophyte — Molecular evolution — Gene clusters

Copyright information

© Springer-Verlag New York Inc. 1998

Authors and Affiliations

  • Ena  Urbach
    • 1
  • David J.  Scanlan
    • 2
  • Daniel L.  Distel
    • 3
  • John B.  Waterbury
    • 3
  • Sallie W.  Chisholm
    • 1
  1. 1.Ralph M. Parsons Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USAUS
  2. 2.Department of Biological Sciences, University of Warwick, Gibbet Hill Rd. Coventry CV4 7AL, United KingdomGB
  3. 3.Woods Hole Oceanographic Institution, Woods Hole MA 02543, USAUS