ИСТИНА

Today it is believed that the genus Aurelia comprises three species: A. limbata, A. labiata and A. aurita. Perhaps due to its ubiquity, A. aurita has become a popular research organism for studies as diverse as protein chemistry, development, ecology, ethology, and hydrodynamics (Arai, 1997). A. aurita also is economically important because worldwide it preys on or competes with larvae of commercial fisheries and because swarms of medusae may impede trawling or block power-plant intakes (Möller, 1980). The systematics of A. aurita therefore is of considerable scientific, economic, and general interest. Aurelia has a typical bipartite scyphozoan life history in which benthic scyphopolyps asexually strobilate ephyrae that grow into sexual medusae, the females of which brood larvae that settle into the shallow coastal benthos within a few days of being released. Of these life stages, the medusa probably is the principal dispersal phase because only the medusa is both long-lived (several months to more than one year; (Hamner and Jenssen, 1974)) and planktonic (Arai, 1997). The potential of medusae for distant dispersal is consistent with the current classification of A. aurita as a circumglobal, almost cosmopolitan, species (Kramp, 1968; Russell, 1970). However, A. aurita medusae in Saanich Inlet, British Columbia, and perhaps elsewhere, migrate directionally (Hamner et al., 1994), maintaining breeding aggregations within isolated inlets and probably limiting gene flow among populations. Consistent with limited gene flow, allozyme differences have been found between populations of A. aurita in the eastern and western Atlantic Ocean, the Gulf of Mexico, and the eastern and western Pacific Ocean (Greenberg et al., 1996; Zubkoff and Linn, 1975). In this work we compare three populations of Aurelia aurita ("cosmopolitan species"): from the White, Black and Japanese Seas. We sequenced 18S and 28S RNA genes. We have constructed phylogenetic trees of objects from these three populations based on rRNA genes sequences. We received karyotypes of Aurelia species from these populations and they differ greatly between themselves: Aurelia karyotype from the Japanese Sea has three pairs of submetacentric and 14 pairs of acrocentric chromosomes (2n = 34), while the karyotypes of Aurelia from the White and Black Seas are the same (8 pairs of submetacentric and 11 pairs of acrocentric chromosomes (2n = 38).