We studied the phylogenetic history of opossum shrimps of the genus Mysis Latreille, 1802 (Crustacea: Mysida) using parsimony analyses of morphological characters, DNA sequence data from mitochondrial (16S, COI and CytB) and nuclear genes (ITS2, 18S), and eight allozyme loci. With these data we aimed to resolve a long-debated question of the origin of the non-marine (continental) taxa in the genus, i.e., "glacial relicts" in circumpolar postglacial lakes and "arctic immigrants" in the Caspian Sea. A simultaneous analysis of the data sets gave a single tree supporting monophyly of all continental species, as well as monophyly of the taxa from circumpolar lakes and from the Caspian Sea. A clade of three circumarctic marine species was sister group to the continental taxa, whereas Atlantic species had more distant relationships to the others. Small molecular differentiation among the morphologically diverse endemic species from the Caspian Sea suggested their recent speciation, while the phenotypically more uniform "glacial relict" species from circumpolar lakes (Mysis relicta group) showed deep molecular divergences. For the length-variable ITS2 region both direct optimization and a priori alignment procedures gave similar topologies, although the former approach provided a better overall resolution. In terms of partitioned Bremer support (PBS), mitochondrial protein coding genes provided the largest contribution (83%) to the total tree resolution. This estimate however, appears to be partly spurious, due to the concerted inheritance of mitochondrial characters and probable cases of introgression or ancestral polymorphism.

Item Type:	Refereed Article
Keywords:	cladistic analysis, parsimony, 'glacial relicts', Caspian Sea, Mysis
Research Division:	Biological Sciences
Research Group:	Evolutionary Biology
Research Field:	Phylogeny and Comparative Analysis
Objective Division:	Environment
Objective Group:	Flora, Fauna and Biodiversity
Objective Field:	Coastal and Estuarine Flora, Fauna and Biodiversity
UTAS Author:	Audzijonyte, A (Dr Asta Audzijonyte)
ID Code:	121160
Year Published:	2005
Web of Science® Times Cited:	35
Deposited By:	Ecology and Biodiversity
Deposited On:	2017-09-12
Last Modified:	2017-11-13
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