Обзорные Статьи Origins of Native

Обзорные статьи Introduction This article was provoked by the article by I.Yu. Parnikoza, D.N. Maidanuk, and I.A. Koze retska [1] recently published in «Cytology and Ge УДК 74.9 : 574.91 (292.3) netics» (Kiev). We cannot completely agree with S.L. MOSYAKIN 1,L.G. BEZUSKO 1, A.S. MOSYAKIN 1,2 one of the main conclusions of the authors, who 1 M.G. Kholodny Institute of Botany, National Academy of Sciences postulated the Tertiary (OligocenePliocene) relict of Ukraine, 2 Tereshchenkivska Street, Kyiv, 01601 Ukraine status for both angiosperm taxa in Antarctica, and [email protected] because of that we provide here some additional 2 National University «KyivMohyla Academy», 2 H. Skovorody Street, information and comments on the topics consid Kyiv, 04070 Ukraine ered in the article by Parnikoza et al. ORIGINS OF NATIVE VASCULAR Due to the tremendous progress in and growing availability of molecular methods, the science of PLANTS OF ANTARCTICA: COMMENTS historical biogeography is now undergoing rapid FROM A HISTORICAL and dramatic transformation which can be regarded as a true «molecular revolution» [2–9]. In fact, PHYTOGEOGRAPHY VIEWPOINT instead of vague and nontestable hypotheses and assumptions, we have now in many cases a solid evidence indicating possible centers of origin, migra tion pathways and timing of evolutionary radiations for many previously enigmatic biogeographical cases concerning many taxa of plants, animals, fungi, and even protists. It means that we see the transformation of a previously empirical field of science into a combination of real experimental and historical science, conclusions of which are falsifiable in the true scientific, Popperian sense. Molecular phylogeographic, phylogenetic, and populationalgenetic approaches proved to be the The article provides an overview of the problem of origin most productive ones in reconstructing the history of the only native vascular plants of Antarctica, Deschampsia and development of geographical patterns in plants. antartica (Poaceae) and Colobanthus quitensis (Caryophy The most interesting examples bearing concep llaceae), from the viewpoint of modern historical phytogeog tual implications to our topic are, in our opinion, raphy and related fields of science. Some authors suggested recent results obtained in biogeography in the the Tertiary relict status of these plants in Antarctica, while fields of studying of classical vicariance and/or dis others favour their recent Holocene immigration. Direct data persal models, island biogeography (especially cases (fossil or molecular genetic ones) for solving this controversy is of dispersal to and evolution on oceanic islands), still lacking. However, there is no convincing evidence sup porting the Tertiary relict status of these plants in Antarctica. nothal biogeographical links (especially various ex Most probably D. antarctica and C. quitensis migrated to planations of nothal disjunctions), Late Pleistoce Antarctica in the Holocene or Late Pleistocene (last inter ne and Holocene history of the Arctic and boreal glacial?) through birdaided longdistance dispersal. It biota (especially studies using combined methods should be critically tested by (1) appropriate methods of of phylogeography and paleobiology), and some molecular phylogeography, (2) molecular clock methods, if others, which we cannot discuss here in detail be feasible, (3) direct paleobotanical studies, (4) paleoclimatic cause of space and time limitations. reconstructions, and (5) comparison with cases of taxa with Of course, it is impossible to cover sufficiently similar distribution/dispersal patterns. The problem of the ori in the present article the vast scientific areas men gin of Antarctic vascular plants is a perfect model for integra tion of modern methods of molecular phylogeography and tioned above. However, we will provide here some phylogenetics, population biology, paleobiology and paleo general ideas, striking examples, references to sev geography for solving a longstanding enigma of historical eral most important and useful review articles, plant geography and evolution. and, finally, our comments regarding the current concepts of the origins of Antarctic vascular plants, © S.L. MOSYAKIN,L.G. BEZUSKO, A.S. MOSYAKIN, 2007 including the interesting concept proposed by 54 ISSN 0564–3783. Цитология и генетика. 2007. № 5 Origins of native vascular plants of Antarctica: comments from a historical ... Parnikoza et al. [1]. Our brief review is by necessity However, recently the vicariance models, espe a broadstroke picture in which we cannot go into cially those appealing and referring to Gondwanan too much detail of the discussed extensive issues. biotic interactions, fell out of fashion for several However, we believe that interested readers will reasons, which will be briefly discussed below using consult the references we cite here and get a wider several case topics. and deeper vision of the important biogeographical Insular endemics and longdistance dispersal. A and evolutionary problems, which are being suc flow of recent molecular phylogenetic and phylo cessfully solved with the aid of methods of molecu geographic studies of insular floras and faunas indi lar ecology, phylogeography, population genetics, cated in many cases longdistance migration path and other modern approaches. ways and showed that suggestions of the relict sta tus and ancient age of many oceanic endemics are Results and discussion often far from being justified [2, 15–20]. It is espe Dispersal and vicariance models in phytogeogra cially true for remote oceanic islands and archipel phy. First of all, it should be emphasized that mod agos that have never been part of any continent ern historical biogeography is, by definition, a his and, consequently, are not suitable for vicariance torical and evolutionary science [3, 5]. It means that biogeographical models. reconstruction of historical traits in dispersal and The Hawaii is probably the best studied archi distribution of organisms is impossible without ta pelago in that respect [21–25]. Some evolutionary king into consideration the evolutionary processes links of endemic Hawaiian plants explained by occurring in space and time. Nonevolutionary his longdistance dispersal are truly amazing. For exa torical biogeography is thus a conceptual nonsense. mple, the endemic Hawaiian woody species of vio Vicariance models imply gradual migrations lets (Viola sect. Nosphinium, family Violaceae) from the centers of origin and further changes of which were considered evolutionary «primitive» in ancestral ranges, with their subsequent splitting in fact evolved quite recently (probably in the Middle most cases of disjunction. Classical examples of Pliocene) from the subarctic amphiBeringian vicariance models are explanations of presentday ancestors probably related to the modern herba distribution patterns by past continental movements ceous species of the polyploid V. langsdorffii Ledeb. (mobilism, or modern plate tectonics), orogenesis, aggregate through a longdistance dispersal by birds transgressions and regressions of seas, shifts of physi from Alaska or East Siberia and subsequent explo ographic, climatic and biotic zones, etc. sive radiation [21]. We can mention also the African On the other hand, dispersal models imply gra links of Hawaiian Hesperomannia A. Gray (Astera dual or geologically momentary dispersal events, ceae) [23] and the origin of a morphologically during which organisms or their dispersal units diverse group of several Hawaiian endemic genera migrate over some physical barriers and become of Lamiaceae (Haplostachys Hillebr., Phyllostegia successfully established in a new territory, and such Benth. and Stenogyne Benth.) from North Ameri migrations are naturally accompanied and followed can taxa of Stachys L. sensu lato [24]. Other striking by evolutionary transformations. examples indicating North American, South Paci Vicariancebased models were especially fashio fic, African and Asian sources of recent colonization nable after the triumph of the Wegenerian mobilis of the Hawaii are extensively discussed in recent tic theory and further development of the modern literature [17, 22, 25]. theory of global plate tectonics. However, vicarian It is especially important to stress that the ce was also a respected concept even long before Hawaiian Islands are in fact a volcanic «conveyor that. If we consider enigmatic distribution patterns belt» in the Pacific, with a chain of volcanic islands of many plants in the Southern Hemisphere, this emerging as the crust plates move over the mag concept can be traced back to works of J.D. Hoo matic «hot spots» in the mantle [22]. It means that ker. In more detail these models and explanations the islands themselves are comparatively young, are discussed in several review articles [4, 5, and they are arranged linearly according to their 10–14] and references therein, which are recom age, from the oldest northwestern islands (e.g., mended to the reader for further acquaintance with Kauai) having ca. 5.1 million years of history to the problem. the youngest southeastern islands (like the island ISSN 0564–3783. Цитология и генетика. 2007. № 5 55 S.L. Mosyakin, L.G. Bezusko, A.S. Mosyakin of Hawaii itself) just ca. 430 thousand years old longdistant dispersal phenomena [11, 14, 15, 29]. [22, 25]. Yet this geologically young archipelago For further discussion see also reviews by Eskov in houses a tremendous biotic diversity, with many Russian [12, 13] and Mosyakin in Ukrainian

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