GLOBAL SYSTEMATIC AND PHYLOGENETIC ANALYSIS OF SARGASSUM IN THE GULF OF MEXICO, CARIBBEAN AND PACIFIC BASIN

Authors: Phillips, N.¹; Smith, C.²; Morden, C.²; Fredericq, S.¹

Source: Journal of Phycology, Volume 36, Supplement 3, December 2000 , pp. 55-55(1)

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Abstract:

Sargassum is one of the most species-rich genera in the brown algae with over 400 described species worldwide. The bulk of these species occurs in Pacific-Indian ocean waters with only a small portion found on the Atlantic side of the Isthmus of Panama. Sargassum also has one of the most subdivided and complex taxonomic systems used within the algae. Systematic distinctions within the genus are further complicated by high rates of phenotypic variability in several key morphological characters. Molecular analyses in such systems should allow testing of systematic concepts while providing insights into speciation and evolutionary patterns. Global molecular phylogenetic analyses using both conserved and variable regions of the Rubisco operon (rbcL and rbcL-IGS-rbcS) were performed with species from the Gulf of Mexico, Caribbean, and Pacific basin. Results confirm earlier analyses based on rbcL-IGS-rbcS from Pacific species at the subgeneric and sectional level while providing additional insights into the systematics and phylogenetics on a global scale. For example, species east of the Isthmus of Panama form a distinct well-resolved clade within the tropical subgenus. This result in sharp contrast to traditional systematic treatments but provides a window into the evolutionary history of this genus in the Pacific and Atlantic Ocean basins and a possible means to time speciation events.

Document Type: Research article

DOI: http://dx.doi.org/10.1046/j.1529-8817.1999.00001-164.x

Affiliations: 1: Department of Biology, University of Louisiana at Lafayette, Lafayette, La. 70504 USA; 2: Botany Department, University of Hawaii, 3190 Maile Way, Honolulu, HI 96822. USA

Publication date: 2000-12-01