Diversity and zoogeography of continental mysid crustaceans

based on molecular and morphological characters. – Hydro-biologia 544: 89–141. (Crustacea, Mysida): history of continental invasions inferred from molecular and morphological data. – Cladistics 21: 575–596. IV Audzijonytė, A. & Väinölä, R. 2005: Phylogeographic analyses of a circum-arctic coastal and of a boreal lacustrine mysid crustacean, and evidence of fast post-glacial mtDNA rates. – (submitted manuscript).Caspian mysid crustaceans shows isolation and exchange among dynamic inland sea basins. – (submitted manu script). Mysid crustaceans are predominantly marine, but there are two important continental exceptions: (i) the descendants of Arctic marine Mysis in circumboreal lakes and the Baltic Sea ('glacial relicts' of the Mysis relic-ta group) and in the Caspian Sea, and (ii) autochthonous Ponto-Caspian mysids, with about 20 species in the Black, Azov and Caspian seas. The origin and zoogeographical history of these continental taxa have been subject to much controversy. This thesis applied morphological, molecular and physiological data to analyse the evolution of the continental mysid elements and the importance of various factors that have generated and maintained their diversity at different temporal and spatial scales and at different systematic levels. The taxonomic part of the study explored the morphological differences among four species of the Mysis relicta group, earlier only identifi ed on molecular grounds. Formal taxonomic descriptions of three new species and M. relicta s. str., based on both molecular and morphological characters, were presented. A systematic and distributional analysis suggested that different species have colonised continental waters at different times. The stenohaline European M. relicta and the North American M. diluviana have probably lived in lakes of the two continents through most of the Pleistocene. The more euryhaline European M. salemaai and the circumarctic coastal M. segerstralei are more closely related and have penetrated fresh waters later. The phylogeny of the genus Mysis was assessed in a simultaneous analysis of seven molecular and morphological characters sets. The analysis supported the monophyly of the Mysis relicta group, of the four Caspian Mysis endemics, and of these two continental groups together. The diversifi cation of the M. relicta group appears much older than speciation of the morphologically diverse endemic Caspian Sea Mysis. Analyses of mitochondrial DNA variation within each of M. salemaai and M. segerstralei revealed little large-scale phylogeographic structure, except for a local Beringian lineage in the latter species. Overall, the data suggested effi cient (late)glacial long-distance gene fl ow in the supposedly weakly-dispersing crustaceans , across NW …