Patterns of genetic variability and population structure in the north pacific squids Ommastrephes bartramii, Todarodes pacificus, and Berryteuthis magister

Biochemical genetic variation in the highly abundant squid species from the North Pacific Ocean was examined in relation to their intraspecific differentiation and population structure. A large amount of data collected over a period of approximately 15 yrs was analyzed using protein electrophoresis as a basic research tool. In total, approximately 750 individuals of Ommastrephes bartramii (LeSueur, 1821), 300 individuals of Todarodes pacificus Steenstrup, 1880, and 5800 individuals of Berryteuthis magister (Berry, 1913) were covered by the approach. A geographic pattern of population genetic variability was observed in O. bartramii, with major genetic differentiation attributable to inconsistency in allele frequency distribution and in levels of genetic variation between the squid from the western and eastern parts of the species broad range in the North Pacific Ocean. In T. pacificus from the Japan Sea, significant intraspecific genetic differentiation was largely due to allele frequency variability between two groups of seasonal cohorts: autumn group, consisting of the autumn-spawning squid, and non-autumn group, comprised of the winter-, spring- and summer-spawning squid. An apparent pattern of genetic differentiation was observed in B. magister, which could be related to intersubspecific differences between the squid from the Japan Sea, and northwest Pacific Ocean region, including the Kuril and Commander islands, and Okhotsk and Bering seas. Much less pronounced though significant population genetic variability was revealed between conspecific aggregations of the squid within the northwest Pacific Ocean, where they differ from each other according to geographic proximity, and the most clear differentiation appeared between the Okhotsk-Kuril and Bering groups of the squid

Squids of the family Gonatidae from the North Pacific Ocean and their genetic differentiation: controversial issues in their systematics and phytogeny

There has been much controversy about the number of species and generic composition of the family Gonatidae. As a contribution to stabilizing the systematics of this group of squids, electrophoretic analysis of proteins (allozymes) was used to determine genetic relationships among the nominal species of the Gonatidae from the North Pacific Ocean. Eight species in three genera were analyzed: Gonatus tinro, Gonatus pyros, Gonatus berryi, Gonatus kamtschaticus, Gonatopsis octopedatus, Gonatopsis borealis, Berryteuthis anonychus and Berryteuthis magister. A scheme of genetic divergence among species was produced from pair-wise comparisons using an array of 17-21 enzyme-coding genetic loci, and that scheme was in good agreement with the known schemes of the family systematics and evolution. Analysis of interspecific genetic relationships revealed several basic morphogenic events during the evolution of the family. These were: first, divergence of the B. magister ancestor from the family stem; then, divergence of the ancestors of B. anonychus and G. borealis; and finally, radiation of gonatids possessing a five-toothed radula. A new version of the family phylogeny is suggested, based on data from interspecific genetic divergence and morphology. The family Gonatidae includes two subfamilies: Gonatinae (those with a five-toothed radula) and Berryteuthinae subfam. nov. (species with a seventoothed radula). The Berryteuthinae include three genera: Berryteuthis (type species Gonatus magister Berry, 1913), Boreoteuthis (type species Gonatopsis borealis Sasaki, 1923) and Okutania gen. nov. (type species Gonatus anonychus Pearcy et Voss, 1963). The Gonatinae are composed of two genera: Gonatus (type species Onychoteuthis fabricii Lichtenstein, 1818) and Gonatopsis (type species Gonatopsis octopedatus Sasaki, 1920). The analysis of allozyme divergence among eight squid species from the North Pacific was successful in revealing clear genetic relationships among these taxa