Scale-bearing Chrysophyceae (Mallomonadaceae and Paraphysomonadaceae) from Mackenzie Delta area lakes, Northwest Territories, Canada

Scale-bearing Chrysophyceae have been examined by means of light, scanning electron, and transmission electron microscopy. Samples were taken from nine arctic lakes in the Mackenzie Delta area of the Northwest Territories, Canada. Seventeen species of the genera Chrysosphaerella, Mallomonas, Paraphysomonas, Spiniferomonas and Synura have been identified. Included in these species are seven species previously unreported from northern Canada and one species reported only in North America. The composition of the chrysophycean flora from the Mackenzie Delta area lakes is compared with that of arctic lakes in the Saqvaqjuac area, Hudson Bay (N.W.T.), Alaskan lakes, and Greenland lakes.     

Molecular and morphological characterization of the willow rust fungus, Melampsora epitea, from arctic and temperate hosts in North America

Current taxonomy places all rust fungi that occur on willow (Salix spp.) in North America in one species complex, Melampsora epitea Thüm. Characteristics of M. epitea isolates from the Canadian arctic were compared to M. epitea isolates from temperate regions of North America. Sequences from internal transcribed spacer (ITS) regions of rDNA were obtained from urediniospores from rust-infected Salix leaves collected in the Canadian arctic and in Minnesota and compared. Phylogenetic analysis of nuclear ribosomal ITS regions indicated that arctic M. epitea samples were divergent from temperate M. epitea isolates, perhaps in part because all rusts examined diverged according to host species. Four urediniospore characteristics were examined: area, circularity (shape factor), major axis length and spine density. Statistically significant (P < 0.05) differences were observed for spine density among all host species except S. nigra and S. bebbiana. However major axis length differed between these species. These results represent the first evidence that arctic and temperate Melampsora species on Salix hosts in North America have evolved distinct molecular and morphological characters.     

西伯利亚嵩草及其相关类群的植物分类学及植物地理学研究

研究了产于西伯利亚的西伯利亚嵩草Kobresia sibirica (Turcz.ex Ledeb.) Boeck.,产于北美的K.hyperborea Porsild和K.macrocarpa Clokey。三者之间无显著差异,并且它们的雌花都具有由一至三枚小鳞片组成的花被。因此,它们为同种植物, K.hyperborea包括其变种var.alaskana Duman和var.lepagei Duman及K.macrocarpa被降为西伯利亚嵩草的异名。西伯利亚嵩草分布于亚洲和北美洲的北极和亚北极地区,可能起源于亚洲,由东西伯利亚通过白令海峡散布到北美。     

新疆北部松萝属地衣生态分布与地理区系成分分析

根据多年的实地调查资料和前人研究资料,对新疆北部松萝属地衣的种类以及它们的分布区、区系特征和垂直分布进行了初步研究。结果表明,分布在新疆北部的松萝属地衣共有22种,主要分布在天山和阿勒泰山,生长在树皮、树枝和朽木上。根据它们对环境的适应特征和选择性,将新疆北部松萝属地衣的主要地理成分分为环极北极及北方成分、北美-欧洲成分、世界广布种、北美成分、环极低北极及北方成分、欧洲成分、东亚—北美成分等7种。研究还发现分布在阿勒泰山和天山的松萝属地衣的垂直分布有明显的差异。阿勒泰山的地衣分布海拔比较高,分布范围比较广泛。     

Arctic fox versus red fox in the warming Arctic: four decades of den surveys in north Yukon

During the last century, the red fox (Vulpes vulpes) has expanded its distribution into the Arctic, where it competes with the arctic fox (Vulpes lagopus), an ecologically similar tundra predator. The red fox expansion correlates with climate warming, and the ultimate determinant of the outcome of the competition between the two species is hypothesized to be climate. We conducted aerial and ground fox den surveys in the northern Yukon (Herschel Island and the coastal mainland) to investigate the relative abundance of red and arctic foxes over the last four decades. This region has undergone the most intense warming observed in North America, and we hypothesized that this climate change led to increasing dominance of red fox over arctic fox. Results of recent surveys fall within the range of previous ones, indicating little change in the relative abundance of the two species. North Yukon fox dens are mostly occupied by arctic fox, with active red fox dens occurring sympatrically. While vegetation changes have been reported, there is no indication that secondary productivity and food abundance for foxes have increased. Our study shows that in the western Arctic of North America, where climate warming was intense, the competitive balance between red and arctic foxes changed little in 40?years. Our results challenge the hypotheses linking climate to red fox expansion, and we discuss how climate warming’s negative effects on predators may be overriding positive effects of milder temperatures and longer growing seasons.     

Historical and ecological determinants of genetic structure in arctic canids

Wolves (Canis lupus) and arctic foxes (Alopex lagopus) are the only canid species found throughout the mainland tundra and arctic islands of North America. Contrasting evolutionary histories, and the contemporary ecology of each species, have combined to produce their divergent population genetic characteristics. Arctic foxes are more variable than wolves, and both island and mainland fox populations possess similarly high microsatellite variation. These differences result from larger effective population sizes in arctic foxes, and the fact that, unlike wolves, foxes were not isolated in discrete refugia during the Pleistocene. Despite the large physical distances and distinct ecotypes represented, a single, panmictic population of arctic foxes was found which spans the Svalbard Archipelago and the North American range of the species. This pattern likely reflects both the absence of historical population bottlenecks and current, high levels of gene flow following frequent long-distance foraging movements. In contrast, genetic structure in wolves correlates strongly to transitions in habitat type, and is probably determined by natal habitat-biased dispersal. Nonrandom dispersal may be cued by relative levels of vegetation cover between tundra and forest habitats, but especially by wolf prey specialization on ungulate species of familiar type and behaviour (sedentary or migratory). Results presented here suggest that, through its influence on sea ice, vegetation, prey dynamics and distribution, continued arctic climate change may have effects as dramatic as those of the Pleistocene on the genetic structure of arctic canid species.     

Northern hemisphere biogeography of Cerastium (Caryophyllaceae): insights from phylogenetic analysis of noncoding plastidnucleotide sequences

Phylogenetic relationships and biogeography of the genus Cerastium were studied using sequences of three noncoding plastid DNA regions (trnL intron, trnL-trnF spacer, and psbA-trnH spacer). A total of 57 Cerastium taxa was analyzed using two species of the putative sister genus Stellaria as outgroups. Maximum parsimony analyses identified four clades that largely corresponded to previously recognized infrageneric groups. The results suggest an Old World origin and at least two migration events into North America from the Old World. The first event possibly took place across the Bering land bridge during the Miocene. Subsequent colonization of South America occurred after the North and South American continents joined during the Pliocene. A more recent migration event into North America probably across the northern Atlantic took place during the Quaternary, resulting in the current circumpolar distribution of the Arctic species. Molecular clock dating of major biogeographic events was internally consistent on the phylogenetic trees. The arctic high-polyploid species form a polytomy together with some boreal and temperate species of the C. tomentosum group and the C. arvense group. Lack of genetic variation among the arctic species probably indicates a recent origin. The annual life form is shown to be of polyphyletic origin.     

A rare case of self-incompatibility in arctic plants: Draba palanderiana (Brassicaceae)

During the last decades, it has been shown that arctic plants show larger variation in reproductive strategies than traditionally assumed. Obligate outcrossing based on a self-incompatibility system is, however, very rare in the typically harsh, insect-poor arctic environment. Here we present the second, to our knowledge, documented example of a fully self-incompatible arctic species, Draba palanderiana Kjellm. Because of its large, scented flowers and frequently aborted fruits it has been suggested that this species is strictly outcrossing. To test this hypothesis, we conducted a pollination experiment with two populations from arctic North America. Pollen stainabilities were above 80% in most plants. Full female and male fertility was demonstrated by crosses resulting in fertile F₁ offspring. In contrast, no viable seeds were obtained after spontaneous or hand-facilitated selfing, demonstrating that these D. palanderiana populations are fully self-incompatible and thus obligately outcrossing.     

Tetraplodon paradoxus and T. pallidus (Musci: Splachnaceae) in northern North America

Tetraplodon paradoxus (R.Br.) Hagen was originally described from arctic Canada in 1823 andT. pallidus Hagen, described from arctic Scandinavia in 1893, was reported from the Canadian Arctic Archipelago in 1907. Although the two species are distinct, clear-cut and easily distinguished from other members of the genus, they were almost hopelessly confused both conceptually and nomenclaturally with each other and withT. mnioides (Hedwig) Bruch, Schimper & Gümbel by Hagen in 1910, and his erroneous treatment has been perpetuated by subsequent bryological authors, especially in Scandinavia. Moreover, these two species have been omitted from all comprehensive North American manuals and checklists; the purpose of this paper is to clarify the long-standing confusion and to establish a firm basis for their recognition in the North American bryoflora, from which they have been excluded for far too long. The distinctions between these two species are made clear by means of photographs made from living material, as well as by maps of their geographical distribution in North America.     

Genetic characterization of an arctic zooplankter: insights into geographic polyploidy

Species of Bosmina from the temperate regions of North America and Europe are diploid and reproduce by cyclical parthenogenesis. By contrast, this study provides evidence that the dominant bosminid taxon in High Arctic lakes reproduces by obligate parthenogenesis and is a polyploid derived from interspecific hybridization. Sinobosmina liederi, a species common in temperate North America, is likely to have been one parent of these hybrids, but the other parent is unknown. As neither parent was detected in the Arctic, it seems unlikely that the hybrid clones that now occupy arctic lakes were synthesized locally. Most habitats contained only one or two clones, despite a total of 38 clones in the region, suggesting that priority effects have been important in restricting diversity within single lakes. The high regional diversity of arctic bosminids could reflect either repeated hybridization between the parent taxa or the genetic instability of newly formed polyploid lineages. These processes would produce hybrid polyploids that are considerably more diverse than their sexual parent taxa, and this difference in genetic diversity may confer an advantage to the polyploid biotype. As many zooplankton taxa from the arctic possess genetic characteristics similar to those of bosminids, these processes may provide a general explanation for the widespread occurrence of polyploids in the Arctic.     

Molecular phylogeny of the Sphaerophorus globosus species complex

The Sphaerophorus globosus complex (Lecanorales, lichenized Ascomycota) shows a large morphological variation, and three relatively distinct morphotypes can be distinguished in parts of the distribution area. Here, we utilize a multigene‐based maximum‐parsimony approach (nITS+ LSU rDNA, mtSSU rDNA, β‐tubulin, and actin) to investigate whether these morphotypes constitute distinct species. The results show that there are at least two well‐supported monophyletic groups that we interpret as phylogenetic species within the S. globosus complex. These species do not completely correspond to the predefined morphotypes. One group, an apparently undescribed species, contains noncoralloid specimens from the North American Pacific Northwest. The other group, S. globosus, consists of two well‐supported monophyletic groups: one contains coralloid epiphytic specimens from the North American Pacific Northwest that are morphologically indistinguishable from epiphytic specimens from Europe and are presently interpreted as belonging to the same species and the other is morphologically variable and contains terrestrial specimens from Europe, North America, and southernmost South America and coralloid epiphytic and epilithic specimens from Europe. The results suggest that the population in southernmost South America originated by long‐distance dispersal from arctic populations in the Northern Hemisphere.     

Variation in spring migration routes and breeding distribution of northern pintails Anas acuta that winter in Japan

In North America, spring migration routes and breeding distribution of northern pintails Anas acuta vary because some individuals opportunistically nest at mid‐latitudes in years when ephemeral prairie wetlands are available, whereas others regularly nest in arctic and sub‐arctic regions where wetland abundance is more constant. Less was known about migration routes and breeding distribution of pintails in East Asia. From 2007–2009 we marked 198 pintails on their wintering areas in Japan with satellite transmitters to: 1) document spring migration routes and summer distribution, 2) evaluate migratory connections and breeding season sympatry with North American pintails, and 3) determine if pintails used the same migration routes in fall as in spring. Most pintails (67%) migrated to the Kamchatka or Chukotka peninsulas in eastern Russia either directly from Japan or via Sakhalin Island, Russia. Remaining pintails primarily migrated to the Magadan region or Kolyma River Basin in eastern Russia via Sakhalin Island. The Chukotka Peninsula was the most common summer destination, with highest densities in the Anadyr Lowlands; a region also used by pintails that migrate from North America. One pintail migrated to St. Lawrence Island, Alaska, in spring and another briefly migrated to the western coast of Alaska in fall. Autumn migration routes generally mirrored spring migration although most pintails bypassed Sakhalin Island in fall. Compared to North American pintails, pintails that winter in Japan exhibited less variation in migration routes and breeding distribution, and nested at higher latitudes. In the Russian Far East there is no region with habitats comparable in extent to the ephemeral mid‐latitude wetlands of North America. Consequently, East Asian pintails mainly nest in arctic and sub‐arctic regions where annual consistency in wetlands promotes constancy in migration routes and breeding distribution. Breeding season sympatry between pintails from different continents results more from North American pintails migrating to eastern Russia than from Japanese pintails migrating to North America.     

Human-mediated introduction of geoengineering earthworms in the Fennoscandian arctic

It is now well established that European earthworms are re-shaping formerly glaciated forests in North America with dramatic ecological consequences. However, few have considered the potential invasiveness of this species assemblage in the European arctic. Here we argue that some earthworm species (Lumbricus rubellus, Lumbricus terrestris and Aporrectodea sp.) with great geomorphological impact (geoengineering species) are non-native and invasive in the Fennoscandian arctic birch forests, where they have been introduced by agrarian settlers and most recently through recreational fishing and gardening. Our exploratory surveys indicate no obvious historical dispersal mechanism that can explain early arrival of these earthworms into the Fennoscandian arctic: that is, these species do not appear to establish naturally along coastlines mimicking conditions following deglaciation in Fennoscandia, nor were they spread by early native (Sami) cultures. The importance of anthropogenic sources and the invasive characteristics of L. rubellus and Aporrectodea sp. in the arctic is evident from their radiation outwards from abandoned farms and modern cabin lawns into adjacent arctic birch forests. They appear to outcompete previously established litter-dwelling earthworm species (i.e. Dendrobaena octaedra) that likely colonized the Fennoscandian landscape rapidly following deglaciation via hydrochory and/or dispersal by early Sami settlements. The high geoengineering earthworm biomasses, their recognized ecological impact in other formerly glaciated environments, and their persistence once established leads us to suggest that geoengineering earthworms may pose a potent threat to some of the most remote and protected arctic environments in northern Europe.     

The impact of Pleistocene climate change on an ancient arctic-alpine plant: multiple lineages of disparate history in Oxyria digyna

The ranges of arctic-alpine species have shifted extensively with Pleistocene climate changes and glaciations. Using sequence data from the trnH-psbA and trnT-trnL chloroplast DNA spacer regions, we investigated the phylogeography of the widespread, ancient (>3 million years) arctic-alpine plant Oxyria digyna (Polygonaceae). We identified 45 haplotypes and six highly divergent major lineages; estimated ages of these lineages (time to most recent common ancestor, T(MRCA)) ranged from ～0.5 to 2.5 million years. One lineage is widespread in the arctic, a second is restricted to the southern Rocky Mountains of the western United States, and a third was found only in the Himalayan and Altai regions of Asia. Three other lineages are widespread in western North America, where they overlap extensively. The high genetic diversity and the presence of divergent major cpDNA lineages within Oxyria digyna reflect its age and suggest that it was widespread during much of its history. The distributions of individual lineages indicate repeated spread of Oxyria digyna through North America over multiple glacial cycles. During the Last Glacial Maximum it persisted in multiple refugia in western North America, including Beringia, south of the continental ice, and within the northern limits of the Cordilleran ice sheet. Our data contribute to a growing body of evidence that arctic-alpine species have migrated from different source regions over multiple glacial cycles and that cryptic refugia contributed to persistence through the Last Glacial Maximum.     

Phylogenetic relationships and evolution in Chrysosplenium (Saxifragaceae) based on matK sequence data

Chrysosplenium (Saxifragaceae) consists of 57 species widely distributed in temperate and arctic regions of the Northern Hemisphere, with two species restricted to the southern part of South America. Species relationships within the genus are highly problematic. The genus has traditionally been divided into two groups, sometimes recognized as sections (Oppositifolia and Alternifolia), based on leaf arrangement, or, alternatively, into 17 series. Based on morphological features, Hara suggested that the genus originated in South America and then subsequently migrated to the Northern Hemisphere. We conducted phylogenetic analyses of DNA sequences of the chloroplast gene matK for species of Chrysosplenium to elucidate relationships, test Hara's biogeographic hypothesis for the genus, and examine chromosomal and gynoecial diversification. These analyses revealed that both sections Oppositifolia and Alternifolia are monophyletic and form two large sister clades. Hence, leaf arrangement is a good indicator of relationships within this genus. Hara's series Pilosa and Macrostemon are each also monophyletic; however, series Oppositifolia, Alternifolia, and Nepalensia are clearly not monophyletic. MacClade reconstructions suggest that the genus arose in Eastern Asia, rather than in South America, with several independent migration events from Asia to the New World. In one well-defined subclade, species from eastern and western North America form a discrete clade, with Old World species as their sister group, suggesting that the eastern and western North American taxa diverged following migration to that continent. The South American species forms a clade with species from eastern Asia; this disjunction may be the result of ancient long-distance dispersal. Character mapping demonstrated that gynoecial diversification is dynamic, with reversals from inferior to half-inferior ovaries, as well as to ovaries that appear superior. Chromosomal evolution also appears to be labile with several independent origins of n = 12 (from an original number of n = 11) and multiple episodes of aneuploidy.     

Surviving climate changes: high genetic diversity and transoceanic gene flow in two arctic–alpine lichens,Flavocetraria cucullata and F. nivalis (Parmeliaceae,Ascomycota)

Aim We examined genetic structure and long‐distance gene flow in two lichenized ascomycetes, Flavocetraria cucullata and Flavocetraria nivalis, which are widespread in arctic and alpine tundra. Location Circumpolar North. Methods DNA sequences were obtained for 90 specimens (49 for F. cucullata and 41 for F. nivalis) collected from various locations in Europe, Asia and North America. Sequences of the nuclear internal transcribed spacer (ITS) + 5.8S ribosomal subunit gene region were generated for 89 samples, and supplemented by beta‐tubulin (BTUB) and translation elongation factor 1‐alpha gene (EF1) sequences for a subset of F. cucullata specimens. Phylogenetic, nonparametric permutation methods and coalescent analyses were used to assess population divergence and to estimate the extent and direction of migration among continents. Results Both F. cucullata and F. nivalis were monophyletic, supporting their morphology‐based delimitation, and had high and moderately high intraspecific genetic diversity, respectively. Clades within each species contained specimens from both North America and Eurasia. We found only weak genetic differentiation among North American and Eurasian populations, and evidence for moderate to high transoceanic gene flow. Main conclusions Our results suggest that both F. cucullata and F. nivalis have been able to migrate over large distances in response to climatic fluctuations. The high genetic diversity observed in the Arctic indicates long‐term survival at high latitudes, whereas the estimated migration rates and weak geographic population structure suggest a continuing long‐distance gene flow between continents that has prevented pronounced genetic differentiation. The mode of long‐distance dispersal is unknown, but wind dispersal of conidia and/or ascospores is probably important in the open arctic landscapes. The high genetic diversity and efficient long‐distance dispersal capability of F. cucullata and F. nivalis suggest that these species, and perhaps other arctic lichens as well, will be able to track their potential niche in the changing Arctic.     

Phylogeny and taxonomy of the damselfly genus Enallagma and related taxa (Odonata: Zygoptera: Coenagrionidae)

Abstract The zygopteran genus Enallagma has been the subject of numerous behavioural and ecological studies, but phylogenetic relationships among species have been examined only within eastern North America, and even the composition and diagnosis of the genus are unclear on a world-wide basis. Most authorities currently recognize about seventy species within Enallagma , comprising two major radiations, in North America and Africa. This study, using morphological data, demonstrates that the North American and a few related Palaearctic species form a monophyletic group that is quite distinct from the African species. The latter are themselves divided into at least three, and probably four, separate clades, one of which may be related to E. parvum of India. Consequently, three of Kennedy's long disused genera, Africallagma , Amphiallagma and Proischnura ( Kennedy, 1920 ) are resurrected and two new genera, Azuragrion gen.n. and Pinheyagrion gen.n. are established for the remaining African taxa. Finally, Enallagma is divided into two subgenera, Enallagma s.s ., the typical 'bluets', including many North American, Holarctic and Palaearctic species, and Chromatallagma subgen.n., comprising a group of species of more variable colour that is confined to North America, the Caribbean and northernmost South America.     

SYSTEMATIC INFERENCES FROM VARIATION IN ISOZYME PROFILES OF ARCTIC AND ALPINE CESPITOSE FESTUCA (POACEAE)

Variation in isozyme patterns was used to assess species boundaries in North American arctic and alpine representatives of the Festuca ovina L. complex. Isozyme profiles, in combination with chromosome number, delimit four discrete entities within the complex: F. brevissima Jurtzev (diploid); F. aggr. auriculata Drobov (diploid); F. brachyphylla Schultes (hexaploid); and tetraploid populations corresponding in morphology to F. baffinensis Polunin (arctic Canada) and F. minutiflora Rydberg (alpine United States). Although no fixed difference was detected between isozyme profiles of the latter two taxa, they are morphologically distinct. Thus variation in isozymes, morphology, and chromosome number delimits five taxa within the F. ovina complex in North America. Some alleles observed in the polyploid taxa were not detected among the diploids, and some observed in F. brachyphylla, the hexaploid taxon, were not detected in either the diploid or the tetraploid species. One possible explanation for these occurrences is that the North American polyploids originated in Eurasia, where many other potential diploid and tetraploid progenitors occur.     

Floristical and ecological characterization of the polar desert zone of Greenland

Abstract. Species composition and biomass of four plant communities were investigated in two coastal polar desert areas in eastern North Greenland, bordering the North East Water Polynya - an ice-free sea area kept open by upwelling - and compared with inland areas in North Greenland. Herb barren, the poorest type, has a species richness of 6 species/m², a cover of 0.7 %, and an aboveground biomass of 0.6 g/m² (vascular plants). The richest type, Saxifraga oppositifolia snowbed, has 10 species/m², 5.0 % cover, and 11.2 g/m² biomass. A floristic and vegetation boundary exists a few kilometres from the coast. The coastal areas bordering the North East Water Polynya had an impoverished flora and vegetation compared to areas near the ice-covered sea, possibly caused by very low summer temperatures and high frequency of clouds. A new delimitation of the polar deserts of Greenland is proposed on the basis of the number of vascular plant species, the occurrence of species with a specific inland distribution in North Greenland and the dominating life forms. At present the polar desert zone includes only areas within a zone up to ca. 15 km from the outer coast of high arctic Greenland - north of ca. 80° N. Large areas formerly classified as polar deserts in eastern North Greenland, as well as in Washington Land in western North Greenland, are excluded. New floristic data confirm that Greenland is correctly included in the Canadian province of the arctic polar deserts, whereas there is no reason for subdividing the polar deserts of the Canadian province.     

Inter-population genetic variation in the freshwater leech Nephelopsis obscura in relation to environmental heterogeneity

The temporal distribution of populations of aquatic macroinvertebrates have been extensively investigated in temperate arctic regions, but little information is available for alpine regions in North America. This paper describes phenology patterns of the aquatic macroinvertebrates of a high elevation wetland (3593 m) in the Green Lakes Valley, Colorado Front Range.Abundant taxa were Chironomidae (primarily Orthocladius and the limnephilid trichopteran Asynarchus curtus (Banks). Temperature patterns were related to the seasonal timing of life stages of most species. Phenology of most alpine aquatic macroinvertebrates appears to be controlled by seasonal climatic patterns, particularly temperature patterns. All chironomid species and Asynarchus curtus (Banks) had univoltine life cycles. Multi-year life cycles were not observed at this alpine site, although they have been observed at some arctic sites with colder temperature regimes than observed in this study.