Beauchamp, Katherine A. , R. Deedee Kathman, Terry S. McDowell, &
Ronald P. Hedrick. 2001. Molecular Phylogeny of Tubificid Oligochaetes
with Special Emphasis on Tubifex tubifex (Tubificidae). - Molecular
Phylogenetics and Evolution 19(2):216-224.
Abstract. "Tubifex tubifex is a cosmopolitan freshwater oligochaete whose
presence has been studied as a health indicator of the aquatic environment
and as a host for several myxozoan parasites of fish. Unfortunately, current
morphological criteria used to distinguish Tubifex spp. (Tubificidae) are
inadequate. We therefore developed mitochondrial 16S ribosomal DNA
markers to examine phylogenetic relationships among aquatic oligochaetes
and to distinguish species of Tubifex that might serve as hosts for a
particular myxozoan parasite, Myxobolus cerebralis. Our phylogenetic
analyses of oligochaetes based on a 378-bp segment yielded one most
parsimonious tree with three major groups that corresponded to the families
Lumbricidae, Sparganophilidae, and Tubificidae. T. tubifex and T. ignotus
formed a monophyletic assemblage, and a sister relationship between the
genera Tubifex and Limnodrilus was strongly supported. A second analysis
of the relationship within the genus Tubifex identified six genetically distinct
lineages of T. tubifex from North America and Europe that were separated
by genetic distances comparable to those found for "well-defined" species
of Limnodrilus. Therefore, the existence of several morphologically
indistinguishable, thus cryptic, species of Tubifex in North America and
Europe is suggested."
--
Geoff Read <g.read at niwa.cri.nz>
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