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A CANDID ASSESSMENT OF SYSTEMATICS IN THE LAMINARIALES: MUDDLED MORPHOLOGIES AND SKETCHY SEQUENCES
Author(s) -
Saunders G.W.,
Lane C.E.,
Mayes C.
Publication year - 2000
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1046/j.1529-8817.1999.00001-180.x
Subject(s) - biology , systematics , kelp , phylogenetic tree , evolutionary biology , internal transcribed spacer , molecular phylogenetics , ribosomal dna , phylogenetics , molecular clock , algae , paleontology , ecology , taxonomy (biology) , genetics , gene
Algae of the Alariaceae, Laminariaceae and Lessoniaceae are the largest, most complex, and, arguably, most fascinating of the seaweeds. It is, therefore, a profound paradox that these species remain in taxonomic chaos despite the contemporary emphases on systematics. Setchell and Gardner established the classification system in 1925, recognizing these families on the basis of clear morphological features. At that time, however, they acknowledged that some species had features consistent with placement in two families, or that obscured logical placement in any of the families. Ironically, the problems noted by Setchell and Gardner have been ignored and the system has become entrenched in kelp literature. Initial molecular studies highlighted the shortcomings noted by Setchell and Gardner, and further indicated that little of the morphology‐based system was natural. It was obvious that the diagnostic morphological features, presence or absence of sporophylls and ontogenetic splitting, were ‘noisy’ being gained and lost independently many times in kelp evolution. Despite the insights of the initial molecular studies, they had limitations and key relationships remained unresolved. The investigations used the Internal Transcribed Spacers (ITS) of the ribosomal cistron that have phylogenetic limitations owing to their short length, which is exacerbated by the many variable regions that can't be aligned confidently and must be removed prior to phylogenetic analyses. Many molecular publications have appeared subsequent to the first ITS results, and their contribution towards elucidating kelp phylogeny will be assessed. Current investigations using the Large Subunit ribosomal DNA (LSU) for kelp systematics will also be discussed.