Общие вопросы

Этот раздел включает следующие статьи монографии "The Species Concept in the High North - A Panarctic Flora Initiative" (на английском языке):

Эти статьи в целом дают фоновое представление о целях и задачах проекта и пути их решения.

Elven, R., Jonsell, B., Murray, D.F. & Yurtsev, B. A. 1999. An operational species concept for the Panarctic Flora - Det Norske Videnskaps - Akademi. I. Mat. Naturv. Klasse, Skrifter, Ny serie 38: 23-32.
Particular features of the arctic flora create problems for species delimitation: 1) The occurrence in many species-rich families of facultative and obligate apomicts. 2) The observation that sympatric ecotypification may be more prevalent than allopatric differentiation; ecotypes may further have evolved separately in many areas. 3) The fact that all parts of the present-day Arctic have been strongly influenced by Pleistocene glaciations, meaning that most arctic taxa may have been recruited during the last 2 to 3 million years from areas outside what currently is considered as Arctic. In spite of these factors, the Panarctic Flora should use a generally applicable species concept. For recognition as species, taxa should differ by at least two (preferably more), presumably independently inherited, morphologic characters. They should also be separated by a barrier – geographic and/or ecological, phenologic or genetic. Fertile intermediates should be absent, rare, or only local. In plants with little genetic interchange, as with inbreeders and plants reproducing mainly vegetatively (or apomictically), greater differences should be demanded for acceptance as species than in plants with efficient outcrossing and large neighborhoods.
[статья полностью]
Keywords: subspecies, variety, hybrid taxa, chromosome races, apomictic taxa, splitting versus lumping.
R. Elven, (e-mail: reidar.elven@toyen.uio.no), Botanical Garden & Museum, University of Oslo, Norway.
B. Jonsell, (e-mail: bengtj@bergianska.se), Bergius Foundation, Royal Swedish Academy of Sciences, Box 50017, S-10405 Stockholm, Sweden
D.F. Murray (e-mail: ffdfm@uaf.edu), University of Alaska Museum, Fairbanks, Alaska 99775-6960 U.S.A.
Boris A. Yurtsev, Komarov Botanical Institute, ul. prof. Popova, 2, St. Petersburg, 197376 Russia

Murray, D. F. & Yurtsev, B. A. 1999. History of the Panarctic Flora (PAF) project. – Det Norske Videnskaps–Akademi. I. Mat. Naturv. Klasse, Skrifter, Ny serie 38: 15-22.
Background for the Panarctic Flora (PAF) project is presented. Its history and development are given for Phase I of the project. Initially binational (Russia and US), PAF is now establishing Phase II with full panarctic representation and support from other countries.
[статья полностью]
D.F. Murray (e-mail: ffdfm@uaf.edu), University of Alaska Museum, Fairbanks, Alaska 99775-6960 U.S.A.
Boris A. Yurtsev, Komarov Botanical Institute, ul. prof. Popova, 2, St. Petersburg, 197376 Russia

Brochmann, C. & Steen, S.W. 1999. Sex and genes in the flora of Svalbard - implications for conservation biology and climate change. – Det Norske Videnskaps–Akademi. I. Mat. Naturv. Klasse, Skrifter, Ny serie 38: 33-72.
We review the chromosomal, genetic, and reproductive data available for all of the 161 indigenous species and subspecies in Svalbard’s vascular plant flora. The proportion of polyploids is 78%, and the average ploidal level is nearly hexaploid. Enzyme electrophoretic and/or DNA data are available for 46 taxa, and their degree of genetic variation at three hierarchic levels is discussed. All polyploids examined using enzyme electrophoresis are allopolyploids showing fixed heterozygosity. The level of heterozygosity increases strongly from diploids to high polyploids. Because of the high proportion of polyploids and the high ploidal levels in arctic floras, it is reasonable to suggest that a typical arctic species contains high levels of genetic variation. In contrast, there is little variation among plants within populations of many taxa because of selfing or asexual reproduction. The level of variation among populations in Svalbard varies considerably, probably depending on the post-Weichselian colonization history of each taxon, so the results for Svalbard are not representative for the Arctic as a whole. Populations of typical arctic plants may maintain most of their genetic variation in spite of inbreeding and bottlenecks, because each plant carries most of the population's gene pool in the form of fixed heterozygosity. The optimal conservation strategy for most of the taxa (93.4%) in Svalbard (and generally in the Arctic) is to preserve many, small, and spatially separated populations rather than few, large populations.
[статья полностью]
Keywords: Arctic plants, conservation biology, molecular systematics, polyploidy, population genetics, reproductive biology, Svalbard.
C. Brochmann (e-mail: christian.brochmann@toyen.uio.no) & S.W. Steen (e-mail: s.w.steen@bio.uio.no), Botanical Garden and Museum, University of Oslo, Trondheimsveien 23B, N-0562 Oslo, Norway

Eriksen, B. 1999. Species concept in apomictic plants - different solution to the same problem. – Det Norske Videnskaps–Akademi. I. Mat. Naturv. Klasse, Skrifter, Ny serie 38: 73-80.
Different species concepts (phenetic, biological, evolutionary, ecological, and phylogenetic) are presented and discussed in relation to apomictic plants. The species concept which appears in least conflict with the situation met with in apomictic plants, and the one which may provide the most solid theoretical basis, is the evolutionary species concept. In the Arctic about a dozen genera are known to comprise apomictic taxa, mainly within Rosaceae, Asteraceae and Poaceae. Some case studies (Rubus, Taraxacum, Amelanchier, and Potentilla) are briefly discussed.
[статья полностью]
Keywords: Rubus, Taraxacum, Amelanchier, Potentilla.
B. Eriksen (e-mail: bente.eriksen@systbot.gu.se), Department of Botany, Evolutionary Botany, University of Göteborg, Box 461, SE-405 30 Göteborg, Sweden

Crawford, R. M. M. 1999. The Arctic as a peripheral area. - Det Norske Videnskaps - Akademi. I. Mat. Naturv. Klasse, Skrifter, Ny serie 38: 131-153.
Biogeographically, peripheral areas are regions where a notable number of species reach a limit to their distribution. Historically, there is probably no other region in the Northern Hemisphere to compare with the Arctic where so many species from different continents have had their limits of distribution altered by the waxing and waning of the Pleistocene ice sheets. The genetic consequences of these repeated cycles of extinction and re-invasion have been suggested as involving reduction of species variability as during phases of recolonisation immigration will take place mainly from individuals spreading out from the periphery of southern populations. However, this apparently logical view of arctic biodiversity may be misleading. Peripheral areas are characterized by variable and unstable conditions, relative to core areas. Consequently, since changeable conditions induce fluctuating selection, peripheral populations, provided they are not isolated, and not subjected to genetic drift, can be expected to be variable. In addition, species inhabiting peripheral areas have less competition and therefore the species are ecologically released facilitating increased variation. Genetic and physiological evidence for intra-specific variation in arctic populations is examined and in certain species is found to be just as great and sometimes even greater in arctic than in non-arctic populations. Thus, contrary to previous statements, based largely on examples from animal species, that low genetic diversity is to be expected in the Arctic, it can be shown that in flowering plants arctic populations of certain widespread autochthonous high latitude species can show a high level of intra-specific variation.
[статья полностью]
Keywords: biodiversity, infraspecific variation, glaciation, ecological release, mutualism.
Crawford, R. M.M. (e-mail: rmmc@st-andrews.ac.uk), Plant Science Laboratory, Sir Harold Mitchell Building, St Andrews University, St Andrews KY16 9AL, UK

Molau, U. 1993. Why do ecologists need species? - Det Norske Videnskaps-Akademi. I. Mat. Naturv. Klasse, Skrifter, Ny serie 38: 155-159.
The Panarctic Flora project is a challenge to the circumarctic community of taxonomists, and to be successful, the output must be designed to meet the demands not only from the taxomists themselves, but also from other potential users. With increasing international collaboration and cross-site comparisons in ecological networks, a comprehensive Panarctic Flora is badly needed. The species concept (or concepts) adopted in the flora must be robust enough not to lose ecological information to the user community.
[статья полностью]
Ulf Molau (e-mail: ulf.molau@systbot.gu.se), Botanical Institute, Göteborg University P.O. Box 461 SE-405 30 Göteborg, Sweden e-mail ulf.molau@systbot.gu.se


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