Aim Based on seven consecutive seasons of biotic survey and inventory of the terrestrial and freshwater plants and animals of the 30 major islands of the Kuril Archipelago, a description of the biodiversity and an analysis of the biogeography of this previously little known part of the world are provided.Location The Kuril Archipelago, a natural laboratory for investigations into the origin, subsequent evolution, and long-term maintenance of insular populations, forms the eastern boundary of the Okhotsk Sea, extending 1200 km between Hokkaido, Japan, and the Kamchatka Peninsula of Russia. A chain of more than 56 islands, the system is only slightly smaller than the Hawaiian Islands, covering an area of 15,600 km 2 and providing 2409 km of coastline.Methods Collections of whole specimens of plants and animals, as well as tissue samples for future molecular studies, were made by teams of scientists from Russia, Japan, and the USA, averaging 34 people for each of the seven annual summer expeditions (1994)(1995)(1996)(1997)(1998)(1999)(2000). Floral and faunal similarities between islands were evaluated by using Sorensen's coefficient of similarity. The similarity matrix resulting from pair-wise calculations was then subjected to UPGMA cluster analysis.

The circumarctic ranges of arctic-alpine plants are thought to have been established in the late Pliocene/early Pleistocene, when the modern arctic tundra was formed in response to climate cooling. Previous findings of range-wide genetic structure in arctic-alpine plants have been thought to support this hypothesis, but few studies have explicitly addressed the temporal framework of the genetic structure. Here, we estimated the demographic history of the genetic structure in the circumarctic Kalmia procumbens using sequences of multiple nuclear loci and examined whether its genetic structure reflects prolonged isolation throughout the Pleistocene. Both Bayesian clustering and phylogenetic analyses revealed genetic distinction between alpine and arctic regions, whereas detailed groupings were somewhat discordant between the analyses. By assuming a population grouping based on the phylogenetic analyses, which likely reflects a deeper intraspecific divergence, we conducted model-based analyses and demonstrated that the intraspecific genetic divergence in K. procumbens likely originated during the last glacial period. Thus, there is no need to postulate range separation throughout the Pleistocene to explain the current genetic structure in this species. This study demonstrates that range-wide genetic structure in arctic-alpine plants does not necessarily result from the late Pliocene/early Pleistocene origin of their circumarctic ranges and emphasizes the importance of a temporal framework of the current genetic structure for understanding the biogeographic history of the arctic flora.

Given that East Asia is located south-west of Beringia and was less glaciated during the Pleistocene, species at higher latitudes were able to expand their range in this region during climate cooling. Although southward migration is an inevitable colonization process, the biogeographical history of the disjunct ranges of higher-latitude species in East Asia has been investigated less extensively. Here, we assess whether their disjunct distributions in the Japanese archipelago connected sufficiently with Beringia or persisted in isolation following their establishment. Sequences of nine nuclear loci were determined for Cassiope lycopodioides (Ericaceae) from the Japanese archipelago as well as its surrounding areas, Kamchatka and Alaska. According to the geographical pattern of genetic diversity, the northern populations from Kamchatka to the northern part of the Japanese archipelago were similar genetically and were differentiated from populations in central Japan. Our study suggested that the distribution of C. lycopodioides was connected between the northern part of the Japanese archipelago and south-western Beringia due to Pleistocene climate cooling. Conversely, central Japan harboured a disjunct range after its establishment. These inferences suggest that widespread range expansion in northern East Asia was plausible for species distributed in Beringia.

Aim: The ice-free area around the Bering Land Bridge, Beringia, has been noted as an important refugium of organisms preferring cold environments such as arctic-alpine plants throughout the Pleistocene climate oscillations. Although numerous phylogeographical studies have supported this refugium, recent studies have challenged the idea of a homogeneous refugium in Beringia. We aim to examine a novel scenario of the post-glacial colonization history of an alpine plant Phyllodoce aleutica in Beringia.Location: The Japanese Archipelago, the Kamchatka Peninsula, the Aleutian Islands, Alaska.Method: The range-wide genetic structure of P. aleutica was elucidated by sequencing 13 nuclear loci. The phylogeographical history was inferred using model-based approaches based on coalescent simulations together with the potential distributions predicted by ecological niche modelling.Results: Bayesian clustering and phylogenetic networks revealed that P. aleutica was divided into three geographically structured groups: the main island of the Japanese Archipelago, the northern island of the archipelago (Hokkaido) and Beringia, including eastern Hokkaido. The demographic history underlying the genetic structure and the potential distributions at present and during Last Glacial Maximum suggest that their divergence likely predated the last glacial period. Except for genetic admixture with the sister species Phyllodoce glanduliflora, populations in Alaska exhibited lower genetic diversity than those in East Asia and exclusively shared two widespread genotypes. Approximate Bayesian computation showed that a demographic model postulating post-glacial expansion into Alaska fit better than alternative models. Main conclusions:Our study suggests that P. aleutica in eastern Beringia originated through post-glacial colonization from East Asia, providing novel insight into the biogeographical history of alpine flora in Beringia. K E Y W O R D S alpine plants, approximate Bayesian computation, Beringia, East Asia, ecological niche modelling, phylogeography

Aim: The evolutionary importance of southern mountain ranges has been noted for alpine as well as arctic-alpine plants. However, it remains unclear whether these isolated marginal populations of cold-adapted species have contributed to the establishment of their current widespread distribution. We aim to explore the molecular evidence for the recent northward migration of alpine snow-bed species in the northern Pacific region.