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SYSTEMATIC EVALUATION OF THE GENUS HILDENBRANDIA (RHODOPHYTA): A SYNTHESIS OF TECHNIQUES
Author(s) -
Sherwood A.R.,
Sheath R. G.
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.1529-8817.1999.00001-186.x
Subject(s) - biology , phylogenetic tree , taxon , genus , taxonomy (biology) , botany , basionym , maximum parsimony , evolutionary biology , marine fungi , zoology , clade , gene , genetics
The evolutionary relationships among members of the red algal genus Hildenbrandia have not been well understood for several reasons. For example, the genus contains both marine and freshwater representatives, all of which are non‐calcified and crustose, and few have definitive morphological characters for classification. Hildenbrandia is also assumed to be completely asexual (reproduction by tetrasporangia in marine forms and by gemmae in freshwater populations), and characters of the female gametangial system and post‐fertilization structures are not available for comparative studies. Currently there are 14 marine and five freshwater species and infraspecific taxa recognized within the genus. We used phylogenetic analyses (parsimony, distance and maximum likelihood) of DNA sequences of commonly employed genes ( rbc L and 18S rRNA) to examine the evolutionary relationships among representatives of many of these taxa. In addition, we employed morphometrics (principal co‐ordinates and cluster analyses) of several measured characters of these same representatives, as well as all available type specimens, to determine the number of morphologically‐delimited entities within the genus. Thus far our results indicate that some characters traditionally used to distinguish species of Hildenbrandia , such as tetrasporangial division pattern, may not be useful in some cases, and a revision of the taxonomy of the genus will be necessary. Although the marine and freshwater species of Hildenbrandia appear to be well separated in our molecular analyses of European specimens, this trend was not observed for North American specimens. High sequence divergence values were calculated for both the rbc L and 18S rRNA genes of Hildenbrandia , compared to other red algal genera.