A large part of representatives of the arctic fraction is absent from zonal habitats and tend to occur in intrazonal biotopes of the watershed and/or river valley: viz., purely arctic species markedly prefer wet intrazonal habitats, whereas arcto-montane and arcto-alpine ones occur in the areas with gravelly soil. Species of the boreal fraction are absent from most habitats, congregating in wet intrazonal biotopes, the river valley and anthropogenic habitats. Most species and the vast majority of collected specimens were found in the ground (epigeal) layer. Only a few rare species were associated with the herbaceous layer: e.g., some abundant Semljicola species were recorded from there in certain days with favorable weather conditions. Embolic division of Erigone longipalpis
Coleoptera, the largest insect order, appears to be subordinate to Diptera in the extent of colonization of the Arctic environment. Beetles comprise about 13% of the insect fauna of the tundra zone, yet in the high latitudes several of their families retain considerable levels of species diversity and play significant cenotic roles. The present communication reviews the circumpolar beetle fauna of the Arctic. Based on original data, literature sources and museum collections, with the use of extrapolations and analogies, the taxonomic and ecological diversity patterns of the suborders, series and families of Coleoptera are distinguished, the latitude-zonal distribution and the northernmost range limits of the species are analyzed, and their adaptations and cenotic relations are characterized.
Original data on five Dolichopodidae species from the Wrangel Island resulted from the 2006 and 2015 surveys in the Wrangel Island State Nature Reserve are presented. Two sites in the northern variant of the typical tundra subzone in the central part of the Wrangel (i.e. the middle course of the River Mamontovaya and the upper reaches of the River Neizvestnaya) have been thoroughly studied by use of net sweeping (both seasons) and yellow pan traps (only 2015). In total, about 780 specimens have been sampled on the Wrangel Island. The yellow pan traps have gathered the most part of material, i.e. about 650 specimens. One of the collected species, Dolichopus humilis appears to be the only circum-arctic species of the group. Other species, Chrysotus komovi, Dolichopus terminasianae, Hydrophorus alpinus, and Rhamphium beringiense have mainly a hypoarctic distribution. The latter is the rarest species in the material obtained. It is suggested that the high abundance of dolichopodids during the 2015 survey is related to favourable summer weather conditions due to climate warming since the beginning of the 21st century. Chrysotus komovi and Dolichopus terminasianae are recorded for the first time from the Chukotka Autonomous District. Photographs of habitus and habitats for species recorded from the Wrangel Island are provided.
РЕЗЮМЕ. На косе Беляка, расположенной в Колючинской губе на северном побережье Чукотского п-ова, почвенными ловушками собрано 18 видов пауков четырёх семейств: Linyphiidae (15 видов), Lycosidae (1), Tetragnathidae (1), Thomisidae (1); 12 видов указываются для косы впервые. Видовой состав типичен для северной части тундровой зоны, основу фауны составляют арктические виды. По набору доминантов выделено два типа группировок пауков: в приморских местообитаниях с галофитной растительностью доминируют Erigone arctica sibirica Kulczyński, 1908, Halorates holmgreni (Thorell, 1871) и H. spetsbergensis (Thorell, 1872); на участках косы с тундровой и болотной растительностью, расположенных вне зоны затопления, наиболее массовым видом является Pardosa algens (Kulczyński, 1908). Сырые местообитания косы отличает наиболее высокое видовое богатство пауков (15 видов, 83% всей фауны); здесь весьма полно представлены арктические пауки-пигмеи, входящие в число наиболее обычных обитателей подобных стаций в северной части азиатских тундр.
Subgenus Cryobius is one of the most numerous among the megafauna of tundra soils, but studies on its species distribution, taxonomy, and ecology are lacking. Phylogeny and phylogeography reconstructions of insects with taxonomic complexity have become possible using an integrative approach. Here, we report that specimens of Pterostichus (Cryobius) mandibularoides, described from North America, were detected in Eurasia. Thus, this species has a trans-Beringian range with high distributions in North America, as well as a disjunctive part of the range on the northeastern edge of Asia within Chukotka and Wrangel Island. Eight COI haplotypes with closed relationships (1–2 mutation steps) were detected within the whole range, and one 28S rRNA haplotype was detected for Eurasia. Bayesian phylogeny revealed that P. mandibularoides had the most recent common ancestor with sister species P. brevicornis and P. nivalis. Mean genetic distances of both markers were similar and higher between P. mandibularoides and both P. brevicornis and P. nivalis (>5% ± 1.0%) than between the latter species (<4% ± 1.0%). The obtained results change the previous view about brevicornis group stock differentiation within Cryobius in the Arctic and require a revision of the phylogeny and phylogeography of brevicornis group species and Cryobius altogether.
The geographic patterns of genetic and morphological variability in ground beetles were examined throughout Northern Eurasia and North America using the most abundant circumpolar tundra subspecies, Pterostichus (Cryobius) brevicornis brevicornis (Kirby, 1837), as a model. Phylogenetic structure was assessed on the basis of a Bayesian approach using two DNA markers (partial sequences of the COI and 28S rRNA genes), while phylogeographic patterns and population genetic diversity were estimated using the COI gene only. Morphological patterns were analysed using elliptical Fourier coefficients that were calculated based on the pronotum and male genitalia shape outlines. The subspecies shares 23 COI haplotypes throughout its entire circumpolar range, while eight haplotypes of 28S rRNA were detected in Northern Eurasia. Phylogenetic analysis did not reveal subdivided species lineages with strict geographical imprint. The network, FST and uncorrected pairwise divergence analyses showed that the genetic distances between populations increase by longitude from Northeastern Asia to Europe. The genetic variability among the five studied geographical population groups of P. b. brevicornis was relatively high. The MANOVA showed significant regional divergence between local populations in Northern Eurasia based on both morphological markers, but only male genitalia variability was geographically structured. Neither the pronotum shape nor the male genitalia shape aligned with the phylogeographic patterns discovered on the basis of COI sequences. The genetic (COI) marker had more variation within, rather than among, population groups in addition to morphology of pronotum but not male genitalia.
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