2Author for correspondence: e-mail email@example.com.
PHYLOGEOGRAPHY OF GRACILARIA TIKVAHIAE (GRACILARIACEAE, RHODOPHYTA): A STUDY OF GENETIC DISCONTINUITY IN A CONTINUOUSLY DISTRIBUTED SPECIES BASED ON MOLECULAR EVIDENCE1
Article first published online: 4 JUN 2004
Journal of Phycology
Volume 40, Issue 4, pages 748–758, August 2004
How to Cite
Gurgel, C. F. D., Fredericq, S. and Norris, J. N. (2004), PHYLOGEOGRAPHY OF GRACILARIA TIKVAHIAE (GRACILARIACEAE, RHODOPHYTA): A STUDY OF GENETIC DISCONTINUITY IN A CONTINUOUSLY DISTRIBUTED SPECIES BASED ON MOLECULAR EVIDENCE. Journal of Phycology, 40: 748–758. doi: 10.1111/j.1529-8817.2004.03070.x
1Received 10 April 2003. Accepted 5 April 2004.
- Issue published online: 4 JUN 2004
- Article first published online: 4 JUN 2004
- Gracilaria tikvahiae;
Gracilaria tikvahiae, a highly morphologically variable red alga, is one of the most common species of Gracilariaceae inhabiting Atlantic estuarine environments and the Intracoastal Waterway of eastern North America. Populations of G. tikvahiae at the extremes of their geographic range (Canada and southern Mexico) are subjected to very different environmental regimes. In this study, we used two types of genetic markers, the chloroplast-encoded rbcL and the nuclear internal transcribed spacer (ITS) region, to examine the genetic variability within G. tikvahiae, for inferring the taxonomic and phylogenetic relationships between geographically isolated populations, and to discuss its distributional information in a phylogeographic framework. Based on rbcL and ITS phylogenies, specimens from populations collected at the extreme distributional ranges reported for G. tikvahiae are indeed part of the same species; however, rbcL- but not ITS-based phylogenies detected phylogenetic structure among the ten G. tikvahiae different haplotypes found in this study. The four distinct rbcL lineages were identified as 1) a Canadian–northeast U.S. lineage, 2) a southeast Florida lineage, 3) an eastern Gulf of Mexico lineage, and 4) a western Gulf of Mexico lineage. We found no evidence for the occurrence of G. tikvahiae in the Caribbean Sea. Observed phylogeographic patterns match patterns of genetic structures reported for marine animal taxa with continuous and quasicontinuous geographic distribution along the same geographic ranges.