Patterns and Causes of Genetic Diversity in Arctic Plant

McGraw, James B.

doi:10.1007/978-3-642-78966-3_3

Cited by 14 publications

(8 citation statements)

References 26 publications

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“…Depending on the degree of divergence, formerly isolated taxa can be fully interfertile, whereas hybridization among genetically more distant gene pools is often accompanied by polyploidization. Such processes are known to have shaped the flora of the Arctic (McGraw, 1995;Brochmann and Steen, 1999;Abbott and Brochmann, 2003) and have been demonstrated in detail for arctic species of Draba (Brochmann et al, 1992a(Brochmann et al, , b, 1993Brochmann, 1993;Scheen et al, 1999). In the latter genus, gene flow across different ploidy levels has also been reported (Brochmann et al, 1992c).…”

Section: Recent and Multiple Origins Of The Oxytropis Arctica And O mentioning

confidence: 97%

Implications of ITS sequences and RAPD markers for the taxonomy and biogeography of theOxytropis campestrisandO. arctica(Fabaceae) complexes in Alaska

Jorgensen

Stehlik

Brochmann

et al. 2003

American J of Botany

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Taxonomic consensus is lacking on the Oxytropis arctica and O. campestris species complexes, two polyploid complexes found in the interior and arctic areas of Alaska. One classification has emphasized flower size, whereas flower color is considered a key diagnostic character in another classification. Our analyses of internal transcribed spacer (ITS) sequences and random amplified polymorphic DNA (RAPD) markers provided no support for either classification system. The trees generated from ITS sequences and the phenogram derived from RAPD markers suggest that most recognized taxa in the two complexes are probably polyphyletic, including O. arctica var. barnebyana, which is listed as threatened in Alaska. The only consistent pattern detected by both types of molecular markers was a geographic split dividing the northeastern arctic populations from most other populations (48.60-55.03% in AMOVA analyses). This genetic subdivision probably reflects a Pleistocene barrier formed by the northern coastal ice shield. Our molecular data, in conjunction with the previously reported variation of ploidy levels in these groups, suggest a scenario of recent and multiple origins of polyploidy. It is possible that most Alaskan populations of these two complexes are best referred to as a single taxonomic species despite morphological differentiation within the complexes.

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Section: Recent and Multiple Origins Of The Oxytropis Arctica And O mentioning

confidence: 97%

Implications of ITS sequences and RAPD markers for the taxonomy and biogeography of theOxytropis campestrisandO. arctica(Fabaceae) complexes in Alaska

Jorgensen

Stehlik

Brochmann

et al. 2003

American J of Botany

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“…For plants with long-lived seed, further genetic variation is preserved in the seed banks. Dormant seed populations may be genetically different from the aboveground populations (198) and potentially able to better exploit a new climate.…”

Section: Plantsmentioning

confidence: 99%

Responses to Projected Changes in Climate and UV-B at the Species Level

Callaghan

Björn²,

Chernov³

et al. 2004

AMBIO: A Journal of the Human Environment

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Environmental manipulation experiments showed that species respond individualistically to each environmental-change variable. The greatest responses of plants were generally to nutrient, particularly nitrogen, addition. Summer warming experiments showed that woody plant responses were dominant and that mosses and lichens became less abundant. Responses to warming were controlled by moisture availability and snow cover. Many invertebrates increased population growth in response to summer warming, as long as desiccation was not induced. CO2 and UV-B enrichment experiments showed that plant and animal responses were small. However, some microorganisms and species of fungi were sensitive to increased UV-B and some intensive mutagenic actions could, perhaps, lead to unexpected epidemic outbreaks. Tundra soil heating, CO2 enrichment and amendment with mineral nutrients generally accelerated microbial activity. Algae are likely to dominate cyanobacteria in milder climates. Expected increases in winter freeze-thaw cycles leading to ice-crust formation are likely to severely reduce winter survival rate and disrupt the population dynamics of many terrestrial animals. A deeper snow cover is likely to restrict access to winter pastures by reindeer/caribou and their ability to flee from predators while any earlier onset of the snow-free period is likely to stimulate increased plant growth. Initial species responses to climate change might occur at the sub-species level: an Arctic plant or animal species with high genetic/racial diversity has proved an ability to adapt to different environmental conditions in the past and is likely to do so also in the future. Indigenous knowledge, air photographs, satellite images and monitoring show that changes in the distributions of some species are already occurring: Arctic vegetation is becoming more shrubby and more productive, there have been recent changes in the ranges of caribou, and "new" species of insects and birds previously associated with areas south of the treeline have been recorded. In contrast, almost all Arctic breeding bird species are declining and models predict further quite dramatic reductions of the populations of tundra birds due to warming. Species-climate response surface models predict potential future ranges of current Arctic species that are often markedly reduced and displaced northwards in response to warming. In contrast, invertebrates and microorganisms are very likely to quickly expand their ranges northwards into the Arctic.

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“…This observation may suggest that the growth form is genetically determined, and that the different genotypes sometimes are able to disperse and establish in suboptimal habitats. Notably, similar conspicuous differences in morphology and photosynthetic capacity that are genetically based have been demonstrated along similar environmental gradients for Dryas octopetala in Alaska (McGraw & Antonovics 1983;McGraw 1995a).…”

Section: Discussionmentioning

confidence: 52%

“…It has been shown recently that, although fewer in number than in more southern areas, many arctic plants possess extraordinary high levels of variation. High levels of intraspecific variation in arctic plants have been documented in their ecological traits (McGraw & Antonovics 1983;McGraw 1995a, b), ecophysiology and morphology (Crawford et al 1993), and molecular genetics (Brochmann et al 1992a, b, c;Haraldsen & Wesenberg 1993;Nordal & Iversen 1993;Gabrielsen et al 1995;Hagen et al 1995;Tollefsrud et al 1995;Bauert 1996;Brysting et al in press). For polyploid species, which constitute the majority of arctic floras, use of a wide species concept is often necessary because many such species are composed of races of different hybrid origins that bridge the morphological discontinuities originally found between their diploid progenitors (Brochmann 1992b(Brochmann , 1995a.…”

Section: Introductionmentioning

confidence: 99%

The Purple Saxifrage, Saxifraga oppositifolia, in Svalbard: two taxa or one?

Brysting¹,

Gabrielsen²,

Sørlibråten³

et al. 1996

Polar Research

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Several studies have demonstrated high levels of genetic (DNA), ecophysiological, ecological, and morphological variation within the species Purple Saxifrage, Saxifraga oppositifolia, in Svalbard. It has recently been proposed that S. oppositifolia is represented by two conspicuously different subspecies in this archipelago: ssp. reptans, a late‐flowering, prostrate ecotype of snow‐protected, damp habitats, and ssp. pulvinata, an early‐flowering, cushion‐like ecotype of dry, wind‐exposed heaths and ridges. It has also been suggested that the subspecies may be differentiated at the tetraploid and diploid levels, respectively, which would promote reproductive isolation. These hypotheses are tested by examining variation in morphology, ecology, and pollen size and stainability in 150 plants of S. oppositifolia growing in 50 vegetation samples at four sites in the Kongsfjorden area. Although analyses of the various data sets demonstrated the large variation within the species, the material could not be separated into distinct groups. The morphological variation was continuous along local ecological gradients. The pollen grains were fully stainable and the pollen diameter data showed a unimodal distribution, suggesting that the plants analysed represent only one ploidal level. These results reject a hypothesis that the morphologically intermediate plants are hybrids between two taxa at different ploidal levels. Thus, the conspicuous variation in S. oppositifolia in Svalbard probably results from local, in situ ecoclinal differentiation. Although this variation clearly is without taxonomic significance, it is important in the broader context of arctic conservation biology and the potential impact of global warming on arctic vegetation.

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Patterns and Causes of Genetic Diversity in Arctic Plant

Cited by 14 publications

References 26 publications

Implications of ITS sequences and RAPD markers for the taxonomy and biogeography of theOxytropis campestrisandO. arctica(Fabaceae) complexes in Alaska

Implications of ITS sequences and RAPD markers for the taxonomy and biogeography of theOxytropis campestrisandO. arctica(Fabaceae) complexes in Alaska

Responses to Projected Changes in Climate and UV-B at the Species Level

The Purple Saxifrage, Saxifraga oppositifolia, in Svalbard: two taxa or one?

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