Mercury content in the fur of sea otters (Enhydra lutris) from the Commander Islands.

The sea otter (Enhydra lutris) is a keystone species in the ecosystem which is currently in depression in Russia. The objectives of this study were to: (1) establish if the sea otters from the Commander Islands have hazardous levels of mercury (Hg) in their fur; (2) assess Hg pollution in sea otters during a period of high abundance and population depression; (3) identify the age and sex differences in sea otters by Hg content. The sea otters were classified from no to low risk for Hg health effects. Differences in Hg content during periods of low and high population size were not statistically significant. Hg concentrations in adult sea otters were significantly higher than in the young, and higher in males than in females. This study presents the first data on Hg content in sea otters' fur and the first estimate of Hg contamination for the Commander Islands population.

Konstantinovia Is Not Monotypic, and a New Attempt to Determine Relationships in Cephaloziellaceae-Scapaniaceae Superclade (Marchantiophyta).

The exploration of liverworts on Bering Island (the westernmost Aleutians) has revealed plants assigned to the recently described and previously monotypic Konstantinovia, previously known only from Yunnan Province of China, and belonging to the bigeneric Obtusifoliaceae. The collected plants are described here as Konstantinovia beringii sp. nov. The known localities of two species of Konstantinovia are separated by more than 6000 km, while the presence of the genus on the Commander Islands is probably a relict. Phylogenetic examination of both collected specimens and new material from other related families resulted in the construction of a fairly well-supported phylogenetic tree for the entire Cephaloziellaceae s.l. + Scapaniaceae s.l. clade. The constructed trees have confirmed the previously stated assumption that it is necessary to segregate one more family within this superclade, described here as Oleolophoziaceae fam. nov.

Phenotypic integration and modularity drives skull shape divergence in the Arctic fox (Vulpes lagopus) from the Commander Islands.

Phenotypic integration and modularity influence morphological disparity and evolvability. However, studies addressing how morphological integration and modularity change for long periods of genetic isolation are scarce. Here, we investigate patterns of phenotypic integration and modularity in the skull of phenotypically and genetically distinct populations of the Artic fox (Vulpes lagopus) from the Commander Islands of the Aleutian belt (i.e. Bering and Mednyi) that were isolated ca 10 000 years by ice-free waters of the Bering sea. We use three-dimensional geometric morphometrics to quantify the strength of modularity and integration from inter-individual variation (static) and from fluctuating asymmetry (random developmental variation) in both island populations compared to the mainland population (i.e. Chukotka) and we investigated how changes in morphological integration and modularity affect disparity and the directionality of trait divergence. Our results indicate a decrease in morphological integration concomitant to an increase in disparity at a developmental level, from mainland to the smallest and farthest population of Mednyi. However, phenotypic integration is higher in both island populations accompanied by a reduction in disparity compared to the population of mainland at a static level. This higher integration may have favoured morphological adaptive changes towards specific feeding behaviours related to the extreme environmental settings of islands. Our study demonstrates how shifts in phenotypic integration and modularity can facilitate phenotypic evolvability at the intraspecific level that may lead to lineage divergence at macroevolutioanry scales.

Study of HLA genes in Russia Bering Island Aleuts.

HLA-A, -B, -C and -DRB1 alleles and haplotypes have been studied in a group of Aleuts from Bering Island (Commander Islands, Russia). Many of their ancestors were original from other Aleutian Islands, like Attu and Atka Islands (USA) and may have had a low degree of admixture with Russians. HLA haplotypes are found to be specific and quite different from other First North America Inhabitants (including Amerindians, Na-Dene and Eskimo), as it was previously shown in a less numerous Aleut population. HLA-A*24:02 is found in a very high frequency; this character is shared by Pacific and Amerindian populations. In conclusion, HLA, other genetic markers, anthropological and linguistic traits make Aleuts to be different from First America Inhabitants and closer to Europeans and Asians: specifically Aleut relatedness has been found with Scandinavian Saami (Lapps) and Finns and Baikal Lake area Buryats, where all of them may have initialing being originated.

Sea otters, kelp forests, and the extinction of Steller's sea cow.

The late Pleistocene extinction of so many large-bodied vertebrates has been variously attributed to two general causes: rapid climate change and the effects of humans as they spread from the Old World to previously uninhabited continents and islands. Many large-bodied vertebrates, especially large apex predators, maintain their associated ecosystems through top-down forcing processes, especially trophic cascades, and megaherbivores also exert an array of strong indirect effects on their communities. Thus, a third possibility for at least some of the Pleistocene extinctions is that they occurred through habitat changes resulting from the loss of these other keystone species. Here we explore the plausibility of this mechanism, using information on sea otters, kelp forests, and the recent extinction of Steller's sea cows from the Commander Islands. Large numbers of sea cows occurred in the Commander Islands at the time of their discovery by Europeans in 1741. Although extinction of these last remaining sea cows during early years of the Pacific maritime fur trade is widely thought to be a consequence of direct human overkill, we show that it is also a probable consequence of the loss of sea otters and the co-occurring loss of kelp, even if not a single sea cow had been killed directly by humans. This example supports the hypothesis that the directly caused extinctions of a few large vertebrates in the late Pleistocene may have resulted in the coextinction of numerous other species.