Genus <Emphasis Type="Italic">Liriodendrites</Emphasis> in Cretaceous and early Paleogene floras of Northern Asia

Leaves of Liriodendrites Johnson were found in the Gyliakian (Santonian) and Boshnyakovo (Danian) floras of Sakhalin Island, Rarytkin, Koryak, and Kakanaut (Maastrichtian) floras of the Koryak Upland, and Antibes (Coniacian) flora of western Siberia. The study of new finds and revision of earlier collections resulted in the erection of a new species, L. occidentalis P. Alekseev, sp. nov., and creation of two new combinations, L. sachalinensis (Krysht.) P. Alekseev, comb. nov. and L. aeternus (Golovn.) P. Alekseev, comb. nov. The geographical and stratigraphic ranges of Liriodendrites in the Northern Hemisphere were reviewed.     

Features of the spatial distribution and size structure of the Pacific lamprey <Emphasis Type="Italic">Lampetra tridentata</Emphasis> in the North Pacific

Results of long-term research on the spatial and vertical distribution of the Pacific lamprey Lampetra tridentata (Richardson, 1836) (the family Petromyzontidae) in the North Pacific, and data on its size structure are submitted. It was shown, that L. tridentate reached its greatest number in the Bering Sea. The maximum concentration of the Pacific lamprey was observed all year round about Navarin Cape, in the Koryak shelf area, at the East Aleutian Islands and at the west coast of the USA, which, apparently, spoke of the increased number of its prey there. On the bottom, the Pacific lamprey was the most numerous at depths of less than 500 m, and in the pelagic, in the upper 100-meter layer. The length of individuals varied in catches from 12 up to 85 cm. The existence of several size groups may indicate that the Pacific lamprey spend several years in the sea. No correlation was revealed between the length of body and fishing depth. The correlations between body length and body weight, body length and condition factor were analyzed. Seasonal dynamics of these parameters were considered.     

Punctuate divergent evolution in fish from the Northern Pacific

The mtDNA divergence was examined in some families of anadromous and semi-anadromous fish. Heterogeneous distribution of the divergence values along the scale was demonstrated. Statistically significantly higher number of the species pairs were characterized by divergence values ranging from 2 to 4% and 5 to 12% of nucleotide substitutions. These results suggest that in different monophyletic groups occupying common historical ranges, divergence-associated speciation often happened within similar time intervals. Comparison of the species divergence time calculated using the molecular clock pointed to the coincidence of the radiation periods in the taxa with paleogeological and paleoclimatic global changes in the history of Northern Pacific.     

Age and growth of the Pacific halibut <Emphasis Type="Italic">Hippoglossus stenolepis</Emphasis> and the size-age composition of its catches in the North-Western part of the Pacific Ocean

The results of investigation are discussed on age and growth of the Pacific halibut Hippolglossus stenolepis, as well as size-age composition of its catches in three regions of the North-Western Pacific—in Navarin area of the Bering Sea, in Pacific waters on the Northern Kurils and south-eastern Kamchatka, of the Southern Kurils—from the end of the last century. The growth rate of Pacific halibut is similar in all three regions in spite of their considerable geographic remoteness. No significant differences in the growth rate of males and females in these regions, as well as no significant interannual differences in growth of specimens caught in Pacific waters off the Northern Kurils and south-eastern Kamchatka in 1996–2000, are found. Comparison of the present-day size-age composition and that in the beginning-middle of the last century revealed their considerable similarity.     

Mitochondrial DNA variation in Koryaks and Itel'men: Population replacement in the Okhotsk Sea–Bering Sea region during the neolithic

In this study, we analyzed the mitochondrial DNA (mtDNA) variation in 202 individuals representing one Itel'men and three Koryak populations from different parts of the Kamchatka peninsula. All mtDNAs were subjected to high resolution restriction (RFLP) analysis and control region (CR) sequencing, and the resulting data were combined with those available for other Siberian and east Asian populations and subjected to statistical and phylogenetic analysis. Together, the Koryaks and Itel'men were found to have mtDNAs belonging to three (A, C, and D) of the four major haplotype groups (haplogroups) observed in Siberian and Native American populations (A–D). In addition, they exhibited mtDNAs belonging to haplogroups G, Y, and Z, which were formerly called “Other” mtDNAs. While Kamchatka harbored the highest frequencies of haplogroup G mtDNAs, which were widely distributed in eastern Siberian and adjacent east Asian populations, the distribution of haplogroup Y was restricted within a relatively small area and pointed to the lower Amur River–Sakhalin Island region as its place of origin. In contrast, the pattern of distribution and the origin of haplogroup Z mtDNAs remained unclear. Furthermore, phylogenetic and statistical analyses showed that Koryaks and Itel'men had stronger genetic affinities with eastern Siberian/east Asian populations than to those of the north Pacific Rim. These results were consistent with colonization events associated with the relatively recent immigration to Kamchatka of new tribes from the Siberian mainland region, although remnants of ancient Beringian populations were still evident in the Koryak and Itel'men gene pools. Am J Phys Anthropol 108:1–39, 1999. © 1999 Wiley‐Liss, Inc.     

Biogeographical Division of the North Pacific Sublittoral and Upper Bathyal Zones by the Fauna of Mysidacea and Anomura (Crustacea)

A biogeographical analysis of the North Pacific temperate waters is made on the basis of the distribution of 88 species of Mysidacea (Crustacea) and 111 species of Anomura (Crustacea: Decapoda: Reptantia) inhabiting depths from 0 to 1000–12000 m. At depths from 0 to 180–200 m and from 180–200 to 1000–1200 m, division by mysid fauna is made separately; division according to anomurans is unified. Original schemes of faunistic zonation of the North Pacific are given. The influence of abiotic factors, primarily temperature, on the formation of distribution ranges of Pacific boreal species is examined.     

Biodiversity hotspots, centres of endemicity, and the conservation of coral reefs

On land, biodiversity hotspots typically arise from concentrations of small‐range endemics. For Indo‐Pacific corals and reef fishes, however, centres of high species richness and centres of high endemicity are not concordant. Moreover ranges are not, on average, smaller inside the Central Indo‐Pacific (CI‐P) biodiversity hotspot. The disparity between richness and endemicity arises because corals and reef fishes have strongly skewed range distributions, with many species being very widespread. Consequently, the largest ranges overlap to generate peaks in species richness near the equator and the CI‐P biodiversity hotspot, with only minor contributions from endemics. Furthermore, we find no relationship between the number of coral vs. fish endemics at locations throughout the Indo‐Pacific, even though total richness of the two groups is strongly correlated. The spatial separation of centres of endemicity and biodiversity hotspots in these taxa calls for a two‐pronged management strategy to address conservation needs.     

North Atlantic phylogeography and large-scale population differentiation of the seagrass Zostera marina L

As the most widespread seagrass in temperate waters of the Northern Hemisphere, Zostera marina provides a unique opportunity to investigate the extent to which the historical legacy of the last glacial maximum (LGM18 000-10 000 years bp) is detectable in modern population genetic structure. We used sequences from the nuclear rDNA-internal transcribed spacer (ITS) and chloroplast matK-intron, and nine microsatellite loci to survey 49 populations (> 2000 individuals) from throughout the species' range. Minimal sequence variation between Pacific and Atlantic populations combined with biogeographical groupings derived from the microsatellite data, suggest that the trans-Arctic connection is currently open. The east Pacific and west Atlantic are more connected than either is to the east Atlantic. Allelic richness was almost two-fold higher in the Pacific. Populations from putative Atlantic refugia now represent the southern edges of the distribution and are not genetically diverse. Unexpectedly, the highest allelic diversity was observed in the North Sea-Wadden Sea-southwest Baltic region. Except for the Mediterranean and Black Seas, significant isolation-by-distance was found from ~150 to 5000 km. A transition from weak to strong isolation-by-distance occurred at ~150 km among northern European populations suggesting this scale as the natural limit for dispersal within the metapopulation. Links between historical and contemporary processes are discussed in terms of the projected effects of climate change on coastal marine plants. The identification of a high genetic diversity hotspot in Northern Europe provides a basis for restoration decisions.     

A new species of Trinectes (Pleuronectiformes: Achiridae), with comments on the other eastern Pacific species of the genus

A new eastern Pacific achirid, Trinectes xanthurus, has a distinctive yellow or light caudal fin, without pattern, to contrast with its relatively dark body. This species also has black, posterior margins of the dorsal and anal fins and 21-22 caudal vertebrae, versus 19-20 for its Pacific coast congeners. It usually is found in shallow, continental shelf waters on sand or mud bottoms and ranges from Colombia to El Salvador. The genus Trinectes is represented in the eastern Pacific by four species. A fifth species usually occurs in Pacific slope drainages (freshwater) in Panama. Of these species, only Trinectes fonsecensis is found throughout the tropical eastern Pacific, while the other three coastal species are confined to tropical waters south of the Golfo de Tehauntepec.     

Pleistocene expansion of the bipolar lichen Cetraria aculeata into the Southern hemisphere

Many boreal and polar lichens occupy bipolar distributional ranges that frequently extend into high mountains at lower latitudes. Although such disjunctions are more common among lichens than in other groups of organisms, the geographic origin of bipolar lichen taxa, and the way and time frame in which they colonized their ranges have not been studied in detail. We used the predominantly vegetative, widespread lichen Cetraria aculeata as a model species. We surveyed the origin and history of its bipolar pattern using population genetics, phylogenetic and genealogical reconstruction methods. Cetraria aculeata originated in the Northern Hemisphere and dispersed southwards during the Pleistocene. The genetic signal suggests a Pleistocene dispersive burst in which a population size expansion concurred with the acquisition of a South‐American range that culminated in the colonization of the Antarctic.     

Predation of doggertooth on immature Pacific salmon

First occurrence of doggertooth predation on immature Pacific salmon is described from the Okhotsk Sea, off the Northern Kurile Islands. The possible significance of doggertooth for salmon abundance is discussed.     

The thermohaline circulation and the control of ice ages

It is found that the global salinity variations associated with the thermohaline circulation may have a tendency to make the circulation increasingly asymmetric with respect to the equator. As a consequence the salinity difference between the Pacific and the Atlantic Ocean may be slowly increasing. Such a process could have a time scale long enough to be comparable with the time span between major glaciations. A speculative glaciation cycle is proposed which involves the above mentioned property of the thermohaline circulation. In this cycle the role of a Northern Hemisphere glaciation is to bring excess freshwater from the Pacific to the Atlantic.     

Redrawing the map: mtDNA provides new insight into the distribution and diversity of short‐finned pilot whales in the Pacific Ocean

Correlations between morphological and genetic data provide evidence to delineate species or evolutionarily significant units, which then become the units to conserve in management plans. Here, we examine the distribution and genetic differentiation of two morphotypes of short‐finned pilot whale (Globicephala macrorhynchus) in the Pacific Ocean. Mitochondrial control region sequences from 333 samples were combined with 152 previously published sequences to describe genetic variability globally and population structure in the Pacific. Although genetic variability is low, we found strong differentiation at both broad and local levels across the Pacific. Based on genetics, two types are distributed throughout the Pacific, one predominantly in the eastern Pacific and the other in the western and central Pacific. In the eastern Pacific Ocean, no correlation was found between distribution and sea surface temperature. The two types have broad latitudinal ranges, suggesting their distributions are likely driven by more complex factors, such as prey distribution, rather than sea surface temperature.     

Species-level phylogeography and evolutionary history of the hyperdiverse marine gastropod genus Conus

Phylogenetic and paleontological analyses are combined to reveal patterns of species origination and divergence and to define the significance of potential and actual barriers to dispersal in Conus, a species-rich genus of predatory gastropods distributed throughout the world's tropical oceans. Species-level phylogenetic hypotheses are based on nucleotide sequences from the nuclear calmodulin and mitochondrial 16S rRNA genes of 138 Conus species from the Indo-Pacific, eastern Pacific, and Atlantic Ocean regions. Results indicate that extant species descend from two major lineages that diverged at least 33 mya. Their geographic distributions suggest that one clade originated in the Indo-Pacific and the other in the eastern Pacific + western Atlantic. Impediments to dispersal between the western Atlantic and Indian Oceans and the central and eastern Pacific Ocean may have promoted this early separation of Indo-Pacific and eastern Pacific + western Atlantic lineages of Conus. However, because both clades contain both Indo-Pacific and eastern Pacific + western Atlantic species, migrations must have occurred between these regions; at least four migration events took place between regions at different times. In at least three cases, incursions between regions appear to have crossed the East Pacific Barrier. The paleontological record illustrates that distinct sets of Conus species inhabited the Indo-Pacific, eastern Pacific + western Atlantic, and eastern Atlantic + former Tethys Realm in the Tertiary, as is the case today. The ranges of <1% of fossil species (N=841) spanned more than one of these regions throughout the evolutionary history of this group.     

Region‐wide and ecotype‐specific differences in demographic histories of threespine stickleback populations,estimated from whole genome sequences

We analysed 81 whole genome sequences of threespine sticklebacks from Pacific North America, Greenland and Northern Europe, representing 16 populations. Principal component analysis of nuclear SNPs grouped populations according to geographical location, with Pacific populations being more divergent from each other relative to European and Greenlandic populations. Analysis of mitogenome sequences showed Northern European populations to represent a single phylogeographical lineage, whereas Greenlandic and particularly Pacific populations showed admixture between lineages. We estimated demographic history using a genomewide coalescence with recombination approach. The Pacific populations showed gradual population expansion starting >100 Kya, possibly reflecting persistence in cryptic refuges near the present distributional range, although we do not rule out possible influence of ancient admixture. Sharp population declines ca. 14–15 Kya were suggested to reflect founding of freshwater populations by marine ancestors. In Greenland and Northern Europe, demographic expansion started ca. 20–25 Kya coinciding with the end of the Last Glacial Maximum. In both regions, marine and freshwater populations started to show different demographic trajectories ca. 8–9 Kya, suggesting that this was the time of recolonization. In Northern Europe, this estimate was surprisingly late, but found support in subfossil evidence for presence of several freshwater fish species but not sticklebacks 12 Kya. The results demonstrate distinctly different demographic histories across geographical regions with potential consequences for adaptive processes. They also provide empirical support for previous assumptions about freshwater populations being founded independently from large, coherent marine populations, a key element in the Transporter Hypothesis invoked to explain the widespread occurrence of parallel evolution across freshwater stickleback populations.     

Comparative characteristic of sablefish Anoplopoma fimbria in catches with passive and active fishing gear in the northwestern Pacific ocean

According to materials of trap, long-line, and trawl fishing, specific features of distribution of sablefish Anoplopoma fimbria and some of its biological characteristics in Pacific waters off the southeastern coast of Kamchatka, continental slope of the western part of the Bering Sea, Shirshov Underwater Ridge, and off the Commander Islands are considered. Maximum density concentrations according to data of trap fishing was noted along southeastern coast of Kamchatka and the data of trawl fishing indicated most frequent catches in the western part of the Bering Sea in the area of Koryak coast up to Cape Navarin. The pattern of vertical distribution in different areas considerably differs. The magnitude of trap catches in different areas is different and determined by the type of trap and the period of soaking. The size composition, fatness, and the sex ratio are different in catches of different fishing gear and differ between regions. On the whole, in Russian Far Eastern waters, females mature in mass at a body length of 71 cm and males at 57 cm.     

A comparative study in ancestral range reconstruction methods: retracing the uncertain histories of insular lineages

Island systems have long been useful models for understanding lineage diversification in a geographic context, especially pertaining to the importance of dispersal in the origin of new clades. Here we use a well-resolved phylogeny of the flowering plant genus Cyrtandra (Gesneriaceae) from the Pacific Islands to compare four methods of inferring ancestral geographic ranges in islands: two developed for character-state reconstruction that allow only single-island ranges and do not explicitly associate speciation with range evolution (Fitch parsimony [FP; parsimony-based] and stochastic mapping [SM; likelihood-based]) and two methods developed specifically for ancestral range reconstruction, in which widespread ranges (spanning islands) are integral to inferences about speciation scenarios (dispersal-vicariance analysis [DIVA; parsimony-based] and dispersal-extinction-cladogenesis [DEC; likelihood-based]). The methods yield conflicting results, which we interpret in light of their respective assumptions. FP exhibits the least power to unequivocally reconstruct ranges, likely due to a combination of having flat (uninformative) transition costs and not using branch length information. SM reconstructions generally agree with a prior hypothesis about dispersal-driven speciation across the Pacific, despite the conceptual mismatch between its character-based model and this mode of range evolution. In contrast with narrow extant ranges for species of Cyrtandra, DIVA reconstructs broad ancestral ranges at many nodes. DIVA results also conflict with geological information on island ages; we attribute these conflicts to the parsimony criterion not considering branch lengths or time, as well as vicariance being the sole means of divergence for widespread ancestors. DEC analyses incorporated geological information on island ages and allowed prior hypotheses about range size and dispersal rates to be evaluated in a likelihood framework and gave more nuanced inferences about range evolution and the geography of speciation than other methods tested. However, ancestral ranges at several nodes could not be conclusively resolved, due possibly to uncertainty in the phylogeny or the relative complexity of the underlying model. Of the methods tested, SM and DEC both converge on plausible hypotheses for area range histories in Cyrtandra, due in part to the consideration of branch lengths and/or timing of events. We suggest that DEC model-based methods for ancestral range inference could be improved by adopting a Bayesian SM approach, in which stochastic sampling of complete geographic histories could be integrated over alternative phylogenetic topologies. Likelihood-based estimates of ancestral ranges for Cyrtandra suggest a major dispersal route into the Pacific through the islands of Fiji and Samoa, motivating future biogeographic investigation of this poorly known region.     

Contrasting patterns of nuclear microsatellite genetic structure of Fraxinus mandshurica var. japonica between northern and southern populations in Japan

Aim The aim of this study is to detect extant patterns of population genetic structure of Fraxinus mandshurica var. japonica in Japan, and to provide insights into the post‐glacial history of this species during the Holocene. Location Hokkaido and Honshu islands, Japan (including the Oshima and Shimokita peninsulas). Methods We examined nine polymorphic nuclear microsatellite loci to assess genetic variation within and among 15 populations across almost the entire range of the species in Japan. Extant patterns of geographical structure were analysed using Bayesian clustering, Monmonier’s algorithm, analysis of molecular variance, Mantel tests and principal coordinates analysis. Recent bottlenecks within populations and regional genetic variation were also assessed. Results Northern populations (Hokkaido Island and the Shimokita Peninsula) formed a single homogeneous deme, maintaining the highest level of allelic diversity on the Oshima Peninsula. By contrast, southern populations (Honshu Island) demonstrated strong substructure on both coasts. Specifically, populations on the Pacific side of Honshu exhibited significant bottlenecks and erosion of allelic diversity but preserved distinct subclusters diverging from widespread subclusters on the Japan Sea side of this island. Main conclusions Genetic evidence and life history traits suggest that F. mandshurica occupied cryptic northern refugia on the Oshima Peninsula during the Last Glacial Maximum, which is reflected in the species’ extant northern distribution. Strong geographical structure in southern populations, in agreement with fossil pollen records, suggests geographical isolation by mountain ranges running north–south along Honshu. Given that this tree species is cold‐adapted and found in riparian habitats, populations on the Pacific side of Honshu probably contracted into higher‐elevation swamps during warm post‐glacial periods, leading to a reduction of effective population sizes and rare allelic richness.