Allozyme diversity among local populations of the pacific mussel <Emphasis Type="Italic">Mytilus trossulus</Emphasis> (Bivalvia: Mytilidae) from polluted areas of Peter the Great Bay (Sea of Japan)

Allozyme variability was assessed, using starch gel electrophoresis, at 15 polymorphic loci in two samples of the Pacific mussel Mytilus trossulus collected from local populations in heavily (Golden Horn Bay) and slightly polluted areas (Sukhoputnaya Bay) of Peter the Great Bay. Significant differences between samples were found in the genotypic frequencies at nine loci and in allele frequencies, at six loci. The results are suggestive of the differential survival of individuals having different genotypes and alleles at some of the surveyed loci under conditions of pollution. Our data are not in conflict with the hypothesis of the adaptive significance of allozyme polymorphism.     

Allozyme variability of the gastropodTegula rustica from Peter the Great Bay, Sea of Japan

Eight polymorphic loci were surveyed in three samples of the gastropodTegula rustica collected in a clean area of Peter the Great Bay and in three samples from a heavily polluted area of the bay. Macrospatial, microspatial, and temporal differences in allele frequencies and heterozygosity were found at some of the loci; however, the genetic similarity among the samples was very high. It is concluded that allozyme variability at the surveyed loci ofT. rustica cannot be used in pollution monitoring of Peter the Great Bay.     

Analysis of microsatellite loci variations in herring (Clupea pallasii marisalbi) from the White Sea

The genetic diversity among spawning groups of herring from different parts of the White Sea was assessed using ten microsatellite loci. All loci were polymorphic with the expected heterozygosity estimates varying in the range of 12.7–94.1% (mean was 59.5%). The degree of genetic differentiation displayed by White Sea herring was statistically significant (θ = 2.03%). The level of pairwise genetic differentiation F _ST was 0–0.085, and it was statistically significant in most of the comparison pairs between the herring samples. A hierarchical analysis of molecular variance (AMOVA) revealed the statistically significant differentiation of White Sea herring. 96.59% genetic variation was found within the samples and 3.41% variation was found among the populations. The main component of interpopulation diversity (1.85%) falls at the differences between two ecological forms of herring, spring- and summer-spawning. Within the spring-spawning form, the presence of local stocks in Kandalaksha Bay, Onega Bay, and Dvina Bay was demonstrated.     

Allozyme Variability in Local Populations of the Chiton Ischnochiton hakodadensis from Differently Polluted Areas of Peter the Great Bay, Sea of Japan

Allozyme variability in ten polymorphous loci and three samples of the chiton Ischnochiton hakodadensis from Peter the Great Bay, Sea of Japan, was examined by gel electrophoresis. The samples were collected in different areas of the Bay: clean, heavily polluted with petroleum hydrocarbons and detergents, and heavily polluted with heavy metal combinations. It was established that the genetic similarity of the samples was very high, but their differences in allele frequencies, observed heterozygosity, and heterozygote deficiency in some loci were statistically significant. We suppose that allozyme differences between the studied chiton samples are the result of selection to resist anthropogenic pollution of the habitat.     

Allozyme Variability of the Sea Urchin Strongylocentrotus droebachiensis in the Area of Volcanic Hydrotherms

Allozyme variability was studied in 11 polymorphic loci in three samples of the sea urchin Strongylocentrotus droebachiensis using the method of gel electrophoresis. One sample was taken from a population of normal environmental conditions (Avacha Bay, Kamchatka Peninsula), the other two were sampled in Kraternaya Bay (Yankicha Island, the Kuriles): the first sample was from a bottom site where the animals were subjected to continuous stress resulting from the products of volcanic hydrothermal vents and the second sample was from a bottom site where that stress effect was periodical. Statistically significant differences in the genotypic allele frequencies and in levels of heterozygosity of some loci were revealed between the Avacha Bay and Kraternaya Bay samples. Moreover, similar differences, but in other loci, were revealed for the Kraternaya Bay samples. The possible causes of these distinctions are discussed. A conclusion on the primary role of natural selection in the origin of the observed distinctions and on the conformity of the observed data to the hypothesis of selective significance of a part of the allozyme polymorphism is put forth.     

Allozyme Diversity among Different Size Cohorts of Spat of Mytilus trossulus (Bivalvia,Mytilidae) Dwelling together in Amursky Bay,Sea of Japan

Allozyme variability in 16 polymorphic loci in two size cohorts of large (30.0 ± 6.3 mm) and small (9.8 ± 2.3 mm) spat of the mussel Mytilus trossulus (Gould) coinhabiting the intertidal zone in Brazhnikov Bay (Amursky Bay, Sea of Japan) was studied 1988–1989. It was determined that the size cohorts compared were highly similar genetically; Nei's minimum distances were 0.014 and 0.016 in 1988 and in 1989. However, statistically significant differences in allele frequencies were found at 2 loci, both in 1988 and in 1989. The loci differing by allele frequencies in 1988 did not coincide with those in 1989. Significant differences by heterozygosity between the cohorts were found only at the Idg-1 and Est-3 loci, 1988; and at the Aat-1, 6-Fgd, Est-3 loci, 1989; but the average heterozygosity was not significantly different in the cohorts for both years. A deficiency of heterozygotes (Dg) was observed almost at all loci in both cohorts. The mean Dg values were significantly higher in the cohort of small size individuals. Since the environmental conditions for both cohorts were similar, the allozyme differences between them were not a result of natural selection. A possible cause of the allozyme and size differences among the mussel cohorts is the gap in the settling time of larvae, which entails the formation of two size cohorts of mussels. Such a gap was caused by protraction of spawning period of M. trossulus and by the formation of segregate larval pools from various mussel populations differing in allele frequencies.     

越冬和复苏时期太湖水体蓝藻群落结构的时空变化

为研究太湖蓝藻在越冬与复苏时期群落结构的时空变化规律,于2008年11月,2009年2月,2009年4月,在太湖富营养化较严重的湖区选取8个采样点 (梅梁湾、竺山湾、贡湖湾、大浦、西太湖、南太湖、湖心和湖湾交汇处),分3层采水样,过滤并提取样品DNA经PCR扩增蓝藻16S rDNA序列,采用T-RFLP(末端标记的限制性酶切片段长度多样性)技术分析蓝藻群落结构和多样性变化。共得到87个不同的T-RFs(末端限制性酶切片段),表明太湖蓝藻具有丰富的基因多样性。T-RF相对丰度和聚类分析结果表明,太湖蓝藻群落结构在垂直空间上相似性较高,相似度 > 50%;在水平空间,与Microcystis spp.对应的信号峰在8个采样点均为最强峰(相对丰度为17.7% 47.5%)。竺山湾蓝藻多样性最低,西太湖最高,但其余采样点间蓝藻群落和Shannon多样性指数没有显著差异(P>0.05)。Microcystis相对丰度与Shannon多样性指数呈显著负相关(皮尔逊相关系数为-0.958)。在时间尺度上,相似性分析(Analysis of similarity,ANOSIM)结果显示太湖蓝藻群落结构存在极显著差异( P<0.01) 。春季复苏时蓝藻多样性最高,秋季衰亡时最低。聚类分析表明样品聚成两大特征类群,秋季衰亡时样品独自聚为1支,而春季复苏期和冬季越冬期样品彼此混杂。     

Preliminary data on variation of four microsatellite loci in Pacific herring <Emphasis Type="Italic">Clupea pallasii</Emphasis>

Variation of microsatellite loci Cpa110, Cpa113, Cpa4, and Cpa7 was for the first time examined in Pacific-type herring Clupea pallasii from the White Sea (Cl. pallasii marisalbi), the Kara Sea (Cl. pallasii suworowi), the Sea of Okhotsk, and Lake Nerpich’e, Kamchatka Bay, northwestern Pacific (Cl. pallasii pallasii). All loci exhibitedhigh genetic diversity. The estimates of expected heterozygosity varied from 41.5 to 95.6% (mean, 82%). The level of pairwise genetic differentiation F _st at all microsatellite loci varied from 0.005 to 0.076 (0.019, on average) and t was statistically significant (p < 0.05) in most of the pairs of herring samples. Estimates of genetic differentiation among the herring of one subspecies were lower than between the groups belonging to different subspecies.     

Genetic variation at enzyme loci in North Atlantic minke whales,Balaenoptera acutorostrata

Electrophoretic variation within and between North Atlantic minke whale samples(Balaenoptera acutorostrata) from West Greenland, Iceland, and Norway was investigated. In the West Greenland samples, 28 enzyme systems were examined, representing 36 loci, of which 6 were found to be polymorphic. In Icelandic and Norwegian samples, 22 enzyme systems were examined, representing 29 loci, of which 6 and 5 were found to be polymorphic, respectively. The average heterozygosity was 0.058 (SE=0.024) in samples from West Greenland, 0.074 (SE=0.028) in samples from Iceland, and 0.054 (SE=0.023) in samples from Norway. No significant deviations from the expected Hardy—Weinberg genotypic frequencies, within samples taken from the same area, were found. Significant differences in allele frequencies were observed, however, between samples from the three different areas. The average Nei's genetic distance was 0.014 and the averageF _st value was 0.126. The genetic differences between the samples from the different areas indicate that those from West Greenland, Iceland, and Norway represented different breeding populations.     

Genetic Characteristics of Western North Pacific Sei Whales, Balaenoptera borealis, as Revealed by Microsatellites

Genetic characteristics of sei whales, Balaenoptera borealis, inhabiting the western North Pacific were analyzed at 17 microsatellite loci in a total of 89 whales obtained from the area between 37°N–45°N and 147°E–166°E in 2002 (N = 39) and 2003 (N = 50). All the loci analyzed were polymorphic over the samples, some of the loci had more than 10 alleles, indicating a high level of genetic variation within samples. No significant deviation from the expected Hardy–Weinberg genotypic proportion was observed at the 17 loci in the samples. No evidence of genetic heterogeneity in allele frequencies was observed between sexes within samples as well as between the two temporally different samples, indicating a single population of sei whales inhabiting the western North Pacific. We finally tested and demonstrated that the population appeared not to suffer from genetic bottleneck as a result of population decline from past commercial whaling.     

Allozyme variation and behavioural dimorphism among populations of Littorina brevicula (Philippi) from Japan

In Amakusa (Japan), an apparently homogeneous population of Littorina brevicula, divides into two groups during the reproductive season (winter). Some snails migrate to the lower intertidal zone, while the rest remain in the upper zone. This migration behaviour might be controlled genetically and the behavioural dimorphism may be maintained by assortative mating. To evaluate this hypothesis, we studied genetic variation at four polymorphic enzyme loci (Pgm, Aldh, Ipp, Gpt) in both groups, as well as in seven other samples from the coast of Japan and Vostok Bay (Russian coast of the Sea of Japan). There were no significant allele frequency differences between the two behavioural groups of snails with differing migration patterns (2 = 8.411, df = 12, p > 0.5). The samples from Japan belong to a panmictic population. Yet, a significant heterogeneity was found between the sample from Vostok Bay and the samples from Japan, indicating a reduced gene flow between these regions. Generally, observed genotype frequencies showed good fits to Hardy-Weinberg equilibrium expectations at three of the four loci investigated.     

Geographic variation in cranial morphology of narwhals (Monodon monoceros) from Greenland and the eastern Canadian Arctic

We analyzed variation in nine non-metric and eight metric variables in the skulls of 132 narwhals (Monodon monoceros) from five localities in Greenland (Inglefield Bredning, Melville Bay, Uummannaq, Disko Bay, and Scoresby Sound) and one in the eastern Canadian Arctic (Eclipse Sound). Metric variables were used to compare the combined Disko Bay and Uummannaq samples with the samples from Inglefield Bredning and Scoresby Sound using three different multivariate techniques for each sex. None of the results were significant. Seven of the non-metric variables were independent of age and sex and were used in comparing samples from the six localities. No differences were found among the four localities in West Greenland, but differences were found in two of the non-metric variables between the combined West Greenland sample and the one from Scoresby Sound. A major shortcoming of the analysis based on metric data was the small sample size from several of the areas, which resulted in low statistical power. Genetic as well as environmental factors could explain the differences detected here between narwhals living along the west and the east coasts of Greenland.     

Genetic variability and interpopulational differentiation of Artemia strains from South America

Seven Artemia samples from three South American countries (Chile, Brazil, Peru) were studied by starch electrophoresis with the aim of comparing levels of genetic variation and genetic similarity to representative populations of A. franciscana (San Francisco Bay, California, USA) and A. persimilis (Buenos Aires, Argentina), which are species endemic to the New World. Based on the analysis of 22 loci, parameters measuring genetic variability were, for some populations, found to be among the highest reported for Artemia so far. The percentage of polymorphic loci varied from 31.8% (Piura, Peru; Buenos Aires) to 50% (Los Vilos and Salar de Atacama, Chile), while the observed heterozygosity varied from 0.025 (Piura) to 0.165 (Los Vilos, Chile). A dendrogram based on Nei's genetic distance (D) produced four major groups. The Argentinian form, A. persimilis; the San Francisco Bay strain together with samples from Brazil (Macau and Rio Grande do Norte) and Chile (Pichilemu and Salar de Atacama); two coastal populations from Chile (Los Vilos and Iquique) and the sample from Peru (Piura). These four groups have inter-group D values that are, in some cases, far above those normally associated with conspecific populations.     

Macrogeographical population differentiation in oceanic environments: a case study of European hake (Merluccius merluccius), a commercially important fish

Polymorphism at six microsatellite loci was used to study genetic variability and population structure in six geographically distant natural populations of European hake (Merluccius merluccius L.). Four hundred and eighty-three individuals were sampled from Trondheimsfjord in Norway, the Celtic Sea, the southern Bay of Biscay, Faro off Portugal, the Mediterranean Sea north of the coast of Tunisia and the Adriatic Sea. Population subdivision was found between Mediterranean and Atlantic samples, theta = 0.029 (P < 0. 001). No substructuring was found between samples within the Mediterranean Sea, theta = 0.003 and RST = 0.007 (P > 0.05). The Atlantic population structure appears to be more complex than previously suggested by the placement of stock boundaries by the International Council for the Exploration of the Seas (ICES). Analyses based on various models of microsatellite evolution all suggest that differentiation exists between Bay of Biscay and Portugese samples, theta = 0.013 (P < 0.001), RST = 0.036 (P < 0. 001) which are currently managed as one stock. By contrast, fixation indices indicated no differentiation between southern Bay of Biscay samples and Celtic Sea samples, theta = 0.003 (P = 0.02), phiST = 0. 007 (P = 0.10) which are managed as separate stocks. These results suggest that if the observed trends are stable through time, current management policy of European hake may need revision.     

The genetic variability of the red king crab, <Emphasis Type="Italic">Paralithodes camtschatica</Emphasis> (Tilesius, 1815) (Anomura,Lithodidae) introduced into the Barents Sea compared with samples from the Bering Sea and Kamchatka region using eleven microsatellite loci

The intentional introduction of red king crab, Paralithodes camtschatica (Tilesius, 1815) in the Barents Sea represent one of a few successful cases and one that now supports a commercial fishery. Introductions of alien species into new environments are often associated with genetic bottlenecks, which cause a reduction in the genetic variation, and this could be important for the spreading potential of the species in the Atlantic Ocean. Red king crab samples collected in the Varangerfjord located on the Barents Sea (northern Norway) were compared with reference crab samples collected from the Bering Sea and Kamchatka regions in the Pacific Ocean. All samples were screened for eleven microsatellite loci, based on the development of species-specific primers. The observed number of alleles per locus was similar, and no reduction in genetic variation, including gene diversity and allelic richness, was detected between the Varangerfjord sample and the reference sample from Okhotsk Sea near Kamchatka, indicating no genetic bottlenecking at least for the microsatellite loci investigated. The same results were found in comparison with the sample from Bering Sea. The level of genetic differentiation among the samples, measured as overall F _ST across all loci, was relatively low (0.0238) with a range of 0.0035–0.1000 for the various loci investigated. The largest pairwise F _ST values were found between the Bering Sea and Varangerfjord/Barents Sea samples, with a value of 0.0194 across all loci tested. The lowest value (0.0101) was found between the Varangerfjord and Kamchatka samples. Genetic differentiation based on exact tests on allele frequencies revealed highly significant differences between all pairwise comparisons. The high level of genetic variation found in the Varangerfjord/Barents Sea sample could be of significance with respect to further spreading of the species to other regions in the North Atlantic Ocean.     

Characterization of 24 microsatellite loci in delta smelt, Hypomesus transpacificus, and their cross-species amplification in two other smelt species of the Osmeridae family

We characterized 24 polymorphic tetranucleotide microsatellite loci for delta smelt (Hypomesus transpacificus) endemic to the San Francisco Bay Estuary, CA, USA. Screening of samples (n = 30) yielded two to 26 alleles per locus with observed levels of heterozygosity ranging from 0.17 to 1.0. Only one locus deviated from Hardy–Weinberg equilibrium, suggesting these individuals originate from a single panmictic population. Linkage disequilibrium was found in two pairs of loci after excluding the locus out of Hardy–Weinberg equilibrium. Twenty‐two primer pairs cross‐amplified in wakasagi smelt (Hypomesus nipponensis), and 15 primer pairs cross‐amplified in longfin smelt (Spirinchus thaleichthys).     

Multiplex PCR system applied for analysing microsatellite loci of Schlegel's black rockfish,Sebastes schlegeli

Two multiplex PCR amplifications were performed to analyse six microsatellite loci of Schlegel's black rockfish, Sebastes schlegeli, an important commercial fish in the northern part of Japan and an important species for the stock enhancement program in this area. We analysed 67 wild samples from Yamada Bay, Iwate Prefecture, Japan. The observed genotype frequencies agreed with the Hardy–Weinberg expectations at all loci, and the observed heterozygosities ranged from 0.072 to 0.897.     

Distribution and biomass of microphytes measured by benthic chlorophyll a in a tropical lagoon (New Caledonia,South Pacific)

Starch-gel electrophoretic techniques were applied to the investigation of molecular genetic variation in populations of the rough periwinkle Littorina saxatilis. The investigation comprised two phases: a) technique development to resolve as many as possible of the allozyme loci reported in the literature as having been screened in the genus Littorina and in Melarhaphe neritoides; b) the use of these loci to assess levels of genetic variation in and patterns of genetic differentiation among populations of L. saxatilis from a relatively isolated group of populations from Galway Bay, Ireland. More than 43 allozyme loci (of which four were screened for the first time here in this species), coding for 37 enzymes, were investigated and thirteen of these loci (including two loci screened for the first time here) were found to be variable and reliably scorable. Samples from five pairs of transects were collected from Inismór, Aran Islands, from sites with known exposure levels; one transect within each pair was collected from an exposed site and the other from a nearby, but relatively sheltered site. UPGMA for eleven loci, (ARK and PGDH were excluded from cluster and FST analysis as they were unscorable in a few samples), showed that the samples cluster mostly by pair, reflecting their geographic origin and is indicative of little gene flow between populations. Levels of population differentiation were high among samples from the top of the shore, but unusually so at AAT-1 which showed nearly three times the mean FST value for the eleven loci. There was also a significant regression of frequency of AAT-1100 against level of exposure. In addition, among midshore samples, there was a consistently higher frequency of AAT-1100 in sheltered habitats. These results support the findings of others, indicating that this locus may be subject to natural selection.     

Allozyme differentiation of populations of the dogwhelk Nucella lapillus, (L.): the relative effects of geographic distance and variation in chromosome number

Geographic patterns of genie differentiation were compared with differentiation between karyotypes in the intertidal snail Nucella lapillus. Samples from 24 sites covering the species range in Europe and North America were analysed for allozyme variation at 16 soluble enzyme loci. Two homokaryotypes have been identified with diploid numbers 2n = 26 and 2n= 36 (variation is Robertsonian and hybrids have intermediate chromosome numbers) and samples were classified (on the basis of published data) according to karyotype. Group 1 consisted of samples from three English Channel populations of higher chromosome number (on average 2n > 32) and Group 2 consisted of the remaining 21 samples (presumed to be 2n= 26). Karyotype variation accounts for roughly the same amount of the absolute allozyme variance as geographic variation (46.3 °, and 53.7°, respectively). Yet the patterns of differentiation seen between karyotypes and with geographic separation are very different. In samples classified as 2n= 26 (Group 2), while there is a significant amount of heterogeneity (F_ST per locus averaged 0.128 for 10 polymorphic loci), allozyme variation occurs independently at different loci so mean genetic identity (Nei) is high: 0.972. There is only a slight decline in genetic identity with distance (genetic identity averaged 0.965 for amphi-atlantic comparisons) indicating that passive transport of juveniles or adults may contribute significantly to gene flow. Conversely, allozyme variation between karyotypes was concordant. High chromosome number populations possessed a suite of alleles at four allozyme loci (Esl-3, Lap-2, Mdh-1 and Pep-2) which were absent or rare in Group 2 samples resulting in high F_ST values for these loci (from 0.294 to 0.472) when karyotypic classes were combined. Consequently the mean genetic identity between these Robertsonian races is low, 0.856, and falls within the range more usually associated with congeneric comparisons than with con-specific comparisons. The mechanisms maintaining this genie difference are unclear. However the distribution of the karyotypes and physiological and morphological differences (in shell shape) between them strongly suggest that karyotypic variation in Nucella is adaptive.     

Life-stage-dependent supergene haplotype frequencies and metapopulation neutral genetic patterns of Atlantic cod,Gadus morhua,from Canada's Northern cod stock region and adjacent areas

Among highly migratory fish species, nursery areas occupied by juveniles often differ from adult habitats. To better understand the spatial dynamics of Canada's Northern cod stock, juveniles caught off the east coast of Newfoundland and Labrador were compared to adults from the same region as well as individuals from other areas in Atlantic Canada using double-digest restriction site-associated DNA sequencing–derived single nucleotide polymorphisms. A reduced proportion of homozygotes with a chromosomal inversion located in linkage group 1 (LG1) was detected between juvenile and adult samples in the Northern cod stock region, potentially indicating age-dependent habitat use or ontogenetic selection for attributes associated with the many genes located in LG1. No selectively neutral genetic differences were found between samples from the Northern cod stock; nevertheless, significant differences were found between some of these samples and cod collected from St. Pierre Bank, Bay of Fundy, Browns Bank and the southern Scotian Shelf. Clustering analysis of variants at neutral loci provided evidence for three major genetic units: (a) the Newfoundland Atlantic Coast, (b) eastern and southern Gulf of St. Lawrence and Burgeo Bank and (c) the Bay of Fundy, Browns Bank and southern Scotian Shelf. Both adaptive and neutral population structure within the Northern cod stock should be considered by managers to promote demographic rebuilding of the stock.