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Taxa of Rhodiola L. (Crassulaceae) generally grow in arctic or alpine habitats. Some Rhodiola species are used medicinally, one taxon, Rhodiola integrifolia Raf. subsp. leedyi (Rosend. & J.W.Moore) Moran, (Leedy's roseroot), is rare and endangered, and the group's biogeography in North America is intriguing because of distributional disjunctions and the possibility that Rhodiola rhodantha (A.Gray) H.Jacobsen (2 n = 7II) and Rhodiola rosea L. (2 n = 11II) hybridized to form Rhodiola integrifolia Raf. (2 n = 18II). Recent studies of the North American Rhodiola suggest that the group's current taxonomy is misleading. We analyzed nuclear and chloroplast DNA sequences (internal transcribed spacer (ITS), trnL intron, trnL- trnF spacer, trnS- trnG spacer) from the North American Rhodiola taxa. We combined our data with GenBank sequences from Asian Rhodiola species, performed parsimony, maximum likelihood (ML), and Bayesian phylogenetic analyses, and applied a Bayesian clock model to the ITS data. Our analyses reveal two major Rhodiola clades, suggest that hybridization between R. rhodantha and R. rosea lineages was possible, show two distinct clades within R. integrifolia, and demonstrate that a Black Hills, South Dakota, Rhodiola population should be reclassified as Leedy's roseroot. We recommend that R. integrifolia be revised, and that the Black Hills Leedy's roseroot population be managed as part of that rare and endangered taxon. [ABSTRACT FROM AUTHOR]

Here we report the first population genetic examination of a fungus in Hawaii and, to our knowledge, the only investigation of a saprotrophic fungal population distributed across an oceanic archipelago. Rhodocollybia laulaha fruits abundantly in the native rain forests of Hawaii from June through December. Its range includes the geographic extent of the Hawaiian Archipelago; however, this range is highly fragmented because of the discontinuous distribution of the native forest habitat where R. laulaha occurs. We hypothesized that significant patterns of population structure would be recovered within the geographic range of the Hawaiian mushroom R. laulaha resulting from divergence between isolated subpopulations. We tested for population structure and related inferred patterns of restricted gene flow to geographic distance, major geographic features such as mountain peaks and oceans, elevation zones, and spore morphology. We included 120 R. laulaha collections using data from the rRNA IGS1 region, two microsatellite loci, and 184 AFLP loci. Analyses of these genetic data suggest limited genetic structure among R. laulaha subpopulations in Hawaii correlated mostly with geographic distance. Patterns associated with specialization to elevation or spore morphology were not recovered. The limited geographic structure observed in R. laulaha is consistent with relatively recent population fragmentation. [ABSTRACT FROM AUTHOR]

Here we report the first population genetic examination of a fungus in Hawaii and, to our knowledge, the only investigation of a saprotrophic fungal population distributed across an oceanic archipelago. Rhodocollybia laulaha fruits abundantly in the native rain forests of Hawaii from June through December. Its range includes the geographic extent of the Hawaiian Archipelago; however, this range is highly fragmented because of the discontinuous distribution of the native forest habitat where R. laulaha occurs. We hypothesized that significant patterns of population structure would be recovered within the geographic range of the Hawaiian mushroom R. laulaha resulting from divergence between isolated subpopulations. We tested for population structure and related inferred patterns of restricted gene flow to geographic distance, major geographic features such as mountain peaks and oceans, elevation zones, and spore morphology. We included 120 R. laulaha collections using data from the rRNA IGS1 region, two microsatellite loci, and 184 AFLP loci. Analyses of these genetic data suggest limited genetic structure among R. laulaha subpopulations in Hawaii correlated mostly with geographic distance. Patterns associated with specialization to elevation or spore morphology were not recovered. The limited geographic structure observed in R. laulaha is consistent with relatively recent population fragmentation. [ABSTRACT FROM AUTHOR]

A region of contrastively wetter and milder climate occurs in inland northwest North America, separated from similar climates of the Pacific coast by 200–400 km. Researchers have long noted that numerous vascular plants divide their ranges between the interior wetbelt and coastal regions, although many such disjunctions have hitherto gone undocumented. Here I summarize all vascular plants shared between coastal and interior wetbelt regions, disjunct by at least 200 km. These disjunct taxa are assigned to north-coast and south-coast lists according to whether the coastal portions of the ranges occur primarily north or south of the southern limits of maximum continental glaciation. A list of interior wetbelt endemic taxa is also presented, focusing on those that occur at forested elevations. Presence/absence for coastal disjunct and endemic taxa were assigned to grid of 1° × 1°latitude–longitude cells. Using this grid, concentrations of disjunct and endemic taxa were detected, and total values per cell were tested in linear regression for a relationship to mean annual precipitation. In total, 116 coastal disjunct taxa were detected, 31 of them north-coastal and 85 south-coastal. Interior wetbelt endemic and subendemic taxa total 95, and of these, 46 were found primarily at forested elevations. North-coast taxa were found over a wide latitudinal range both north and south of the glacial limits, and their distribution had a weak positive relationship with annual precipitation. South-coast and endemic taxa were found mostly south of the glacial limits, and their distribution did not correlate to annual precipitation. The greatest concentrations of south coastal disjunct and endemic taxa occurred in the Clearwater region of north-central Idaho; a region noted by previous researchers to be a likely ice-age refugium for wet-climate dependent plants and animals. Inferences are made from these patterns, both for biogeographical understanding of the roles played by the interior wetbelt and some regions connecting to the coast, as well as for preservation of biodiversity and ecosystem continuity. On retrouve une région contrastée humide à climat plus doux à l’intérieur des terres dans le nord-ouest de l’Amérique du Nord, laquelle est éloignée de climats similaires sur la côte du Pacifique de 200 à 400 km. Les chercheurs ont noté depuis longtemps que de nombreuses plantes vasculaires divisent leurs aires entre la ceinture humide dans les terres et les régions côtières, bien que de telles disjonctions soient restées non documentées jusqu’ici. L’auteur résume l’ensemble des plantes vasculaires partagées entre les régions côtières et la ceinture humide dans les terres, séparées par au moins 200 km. Il attribue ces taxons disjoints aux listes côte nord et côte sud, selon que les portions côtières des aires se retrouvent prioritairement au nord ou au sud des limites sud de la glaciation continentale maximale. Il présente également une liste d’espèces endémiques de la ceinture humide de l’intérieur, avec accent sur celles qui se retrouvent dans les forêts de haute élévation. Il a attribué à des grilles cellulaires de 1°× 1°degré de latitude–longitude, la présence/absence des taxons disjoints et endémiques. à l’aide de cette grille, l’on a pu détecter les concentrations de taxons disjoints et endémiques, et tester les valeurs totales par régression linéaire afin d’établir une relation avec la précipitation annuelle moyenne. Au total, on a décelé 116 taxons disjoints, 31 d’entre eux nord côtiers et 85 sud côtiers. Les endémiques de la ceinture à l’intérieur des terres regroupent 95 taxons, 46 d’entre eux retrouvés prioritairement dans les forêts en altitude. On retrouve les taxons endémiques nord côtiers sur une grande aire latitudinale, surtout à la limite glaciaire sud, et leur distribution ne montre pas de corrélation avec la précipitation annuelle. Les plus grandes concentrations de taxons endémiques disjoints sud côtiers se retrouvent dans la région de Clearwater au centre nord de l’Idaho, une région désignée par des chercheurs antécédents comme refuge probable de l’âge glaciaire pour les plantes et les animaux dépendants d’un climat humide. À partir de ces patrons, l’auteur déduit des conséquences &#x [ABSTRACT FROM AUTHOR]

Streams are amongst the most sensitive ecosystems in Arctic regions to environmental change. Although diatoms are excellent indicators of environmental change, little information is available about stream diatom distributions across the vast Canadian High Arctic. We sampled 42 streams from nine islands in the Canadian Arctic Archipelago to study their diatom floras and evaluate the influences of biogeographic and environmental variables on species distributions. Highly divergent diatom communities were identified, with 100% species overturn between the most dissimilar communities. Taxa including Hannaea arcus (Ehrenberg) Patrick were characteristic of streams from all regions; other common taxa included Nitzschia perminuta (Grunow) Peragallo, Rossithidium petersenii (Hustedt) Round & Bukhtiyarova, Achnanthidium minutissimum (Kützing) Czarnecki, and Eucocconeis laevis (Østrup) H. Lange-Bertalot. Canonical correspondence analysis indicated that diatom assemblages were significantly related to differences in pH, temperature, latitude, and longitude, which together explained 14.7% of species variability. Analysis of similarities indicated that communities did not differ significantly between epilithic and epiphytic samples and that there were weak but significant differences between the diatom communities in our three regions. These data provide important baseline information for future biomonitoring efforts as well as for paleolimnological studies of past stream hydrology. [ABSTRACT FROM AUTHOR]

Between 1948 and 2008, 668 chromosome number determinations have been reported for individuals of the goldenaster genus Heterotheca Cass. (Asteraceae: Astereae) from Canada, Mexico, and the United States, including 285 newly reported here. This common group of mostly western North American herbaceous annuals and perennials is subdivided into three sections, the most complex of which is section Phyllotheca. Differences of opinion about the taxonomy of the goldenasters, numerous synonyms, and the lack of a comprehensive treatment of the polymorphic villosa complex and other species complexes in section Phyllotheca made it difficult to organize the data into a meaningful discussion of the cytotaxonomy and cytogeography of this genus. Here I present the geographic distribution of all published counts and cytogeography maps of all species of Heterotheca, assigning taxa following recent taxonomic revisions. The sample sizes for species sampled ranged from 1 to 228 reports. All species have a base number of x = 9. Only diploids (2n = 9II or 2n = 18) were found in Heterotheca oregona (Nutt.) Shinners (the single species of sect. Ammodia) and in the three species of section Heterotheca. Both diploids and (or) tetraploids were found across 18 sampled species of section Phyllotheca, with the frequency varying among them; nine species are known only at one ploidy level (either diploid or tetraploid; three species each). Only four triploids (2n = 9III or 2n = 27) were encountered in section Phyllotheca; two were putative interspecific hybrids. One new nomenclatural combination is proposed: Heterotheca inuloides var. leptoglossa. [ABSTRACT FROM AUTHOR]

The eurybioid asters Oreostemma, Herrickia, Eurybia, and Triniteurybia form a complex that is part of the North American clade of tribe Astereae. They comprise 31 species of perennial herbs that are widely distributed on the continent. Previous analyses had shown poor resolution among the four genera and among the species, particularly within Eurybia (23 spp.), which includes diploids and polyploids. We investigated phylogenetic relationships within the group using the nuclear ribosomal ITS and ETS regions, in separate and combined parsimony and Bayesian analyses. We detected incongruence between the ITS and ETS regions when polyploids were included, and so only diploids were considered in the combined analyses. Eurybia pygmaea (Lindl.) G.L. Nesom is confirmed as a member of Symphyotrichum; Eurybia is monophyletic once this species is re-classified. The eurybioids form a paraphyletic grade with Oreostemma, sister to the remaining taxa, followed in succession by Herrickia, Eurybia, and Triniteurybia, and with the latter genus sister to subtribe Machaerantherinae. Thus the xeric Machaerantherinae (x = 6, 5, 4) is nested within the grade of mesic eurybioids (x = 9). Although largely grouping together, the polyploid taxa of Eurybia apparently do not constitute a clade and their relationships to the diploid taxa and to each other could not be assessed further. Among the diploids, two clades emerge: one including the western Eurybia integrifolia (Nutt.) G.L. Nesom and Eurybia sibirica (L.) G.L. Nesom, and the southeastern Eurybia eryngiifolia (Torr. & A. Gray) G.L. Nesom; and a second including the western Eurybia radulina (A. Gray) G.L. Nesom, the eastern cordate-leaved (sect. Eurybia) and the narrow-leaved, mostly coastal plain species of Eurybia. Our analyses, therefore, do not support the current classifications of Eurybia. [ABSTRACT FROM AUTHOR]