Natalia Tkach

PARALLEL EVOLUTIONARY PATTERNS IN MULTIPLE LINEAGES OF ARCTIC ARTEMISIA L. (ASTERACEAE)

Abstract Early observers of plant evolution in the Arctic have noted a floristic similarity with temperate alpine regions and a predominance of high ploidy levels. The aim of our study was to survey these and other traits in multiple closely related but independently evolved lineages of Artemisia. Our phylogenetic study was based on 133 taxa using 3′-ETS and ITS, and on data on morphology, karyology, distribution, and ecological preferences. We compared Arctic lineages with sister groups and tested whether patterns were significantly different. We found: (1) Artemisia has independently adapted to Arctic habitats 13–18 times; (2) There were no ecological preferences of putative progenitors that might determine the colonization success in the Arctic, although most sister groups were centered in steppe habitats; (3) Plant height was distinctly reduced in Arctic lineages; (4) Arctic lineages contained no more polyploids than their respective sister groups or taxa from other habitats; (5) Enlarged flower heads have evolved repeatedly, probably for better pollinator attraction. This strategy could be a substitute for polyploidy, which is typical in other Arctic taxa. Stronger pollinator attraction should result in better outcrossing and higher heterozygosity in the offspring, which is among the main effects of polyploidy.

Sources of the Arctic Flora: Origins of Arctic Species in Ranunculus and Related Genera

The arctic biome is a relatively young ecosystem with ∼2300 species of vascular plants. We studied the genus Ranunculus as an example of the origin and evolution of the arctic flora. For this purpose we used molecular phylogenetic and clock analyses based on evaluation of nuclear ITS and chloroplast matK‐trnK DNA sequences in 194 taxa of Ranunculus and closely related genera. Taxa occurring in the Arctic arose from seven phylogenetic lineages of Ranunculus and also in the genera Coptidium and Halerpestes. Two clades of Ranunculus are species‐rich in the Arctic, i.e., Ranunculus sect. Ranunculus and R. sect. Auricomus (both from R. subg. Ranunculus), but this is due to a number of arctic “microtaxa” morphologically barely separate from R. acris in the former clade and the widely agamospermic species complex of R. auricomus in the latter. Lineages with species adapted to wetlands or aquatic habitats are significant groups represented in the arctic flora (R. subg. Ranunculus sectt. Flammula and Hecatonia/Xanthobatrachium, R. subg. Batrachium, genus Coptidium) but show no clear signs of radiation in the Arctic or the northern boreal zone, except for sectt. Hecatonia/Xanthobatrachium, with R. hyperboreus and R. sceleratus subsp. reptabundus. Astonishingly few of the otherwise numerous lineages of Ranunculus with distributions in the higher mountain systems of Eurasia and North America have acted as “founding sources” for the arctic flora. The only clear example is that of the arctic‐alpine R. glacialis and the Beringian R. chamissonis from the lineage of subg. R. sectt. Aconitifolii/Crymodes, although there might be others in sect. Auricomus not recovered in the current molecular data. Lineages that gave rise to arctic taxa diverged from each other from the early Miocene (R. glacialis/R. chamissonis, Coptidium, lineages in Halerpestes) and continued at an even rate throughout the Tertiary. There are no signs that the intense climate changes of the late Pliocene and the Quaternary substantially accelerated or impeded diversification in Ranunculus. Only the crown group split of R. acris and its relatives is clearly of Quaternary age. A detailed comparison concerning morphology, karyology, and life form excludes fundamental differences between taxa of Ranunculus in the Arctic and their respective closest relatives in regions south of it. Ecological traits, e.g., preferences for dry or moist soils or growth in open and sheltered conditions, also do not differ between arctic and nonarctic taxa. Migration into the Arctic thus started from different phylogenetic lineages and at different times, without development of obvious special traits in the adaptation to arctic environments. This recurrent pattern in Ranunculus differs from that seen in other arctic genera, e.g., Artemisia, in which special traits of adaptation to arctic environments are found. In Ranunculus, the origin of the open arctic biome primarily favored range expansions of taxa/species already adapted to wet habitats in cold areas and depending on rapid dispersal.

Temporal patterns of evolution in the Arctic explored in Artemisia L. (Asteraceae) lineages of different age

Background: Current knowledge of early plant evolution in the geologically young Arctic biome mainly rests on rather scarce fossil data dating back to approximately 5 million years ago. Aims: Our aim was to provide independent age estimates for the origin of several arctic lineages in the genus Artemisia and to assess from which possible source areas plants may have colonised early arctic biomes. Methods: Age estimates were derived from a Bayesian approach with an uncorrelated lognormal clock and the penalised likelihood method imposed on molecular ETS and ITS data of 139 taxa taken mainly from a previous study. The phylogeny was calibrated with the oldest known fossil of Artemisia from approximately 34 mya. Results: The different methods employed yielded partly dissimilar results, and correspondence to a second calibration point (first American fossil) was also not very strong. Nevertheless, it seems that several Artemisia lineages were part of the geologically young arctic biome from the beginning of its origin and at least one arctic group is even older. It was shown that the oldest lineages in the genus are currently found in Beringia. An evaluation of ecological requirements showed that early Artemisia stock in the emerging arctic biome might have evolved from steppe and alpine progenitors. Conclusions: Considerable caution is required when attempting to reconstruct the evolution of arctic Artemisia lineages, but our results mostly fit the general fossil record and other traditional theories for the origin of arctic lineages.

High mountain origin, phylogenetics, evolution, and niche conservatism of arctic lineages in the hemiparasitic genus Pedicularis (Orobanchaceae)

The origin of the arctic flora covering the northernmost treeless areas is still poorly understood. Arctic plants may have evolved in situ or immigrated from the adjacent ecosystems. Frequently arctic species have disjunctive distributions between the Arctic and high mountain systems of the temperate zone. This pattern may result from long distance dispersal or from glacial plant migrations and extinctions of intermediate populations. The hemiparasitic genus Pedicularis is represented in the Arctic by c. 28 taxa and ranks among the six most species-rich vascular plant genera of this region. In this study, we test the hypothesis that these lineages evolved from predecessors occurring in northern temperate mountain ranges, many of which are current centers of diversity for the genus. We generated a nuclear ribosomal and chloroplast DNA phylogeny including almost all of the arctic taxa and nearly half of the genus as a whole. The arctic taxa of Pedicularis evolved 12-14 times independently and are mostly nested in lineages that otherwise occur in the high mountains of Eurasia and North America. It appears that only three arctic lineages arose from the present-day center of diversity of the genus, in the Hengduan Mountains and Himalayas. Two lineages are probably of lowland origin. Arctic taxa of Pedicularis show considerable niche conservatism with respect to soil moisture and grow predominantly in moist to wet soils. The studied characteristics of ecology, morphology, and chromosome numbers of arctic Pedicularis show a heterogeneous pattern of evolution. The directions of morphological changes among the arctic lineages show opposing trends. Arctic taxa are chiefly diploid, the few tetraploid chromosome numbers of the genus were recorded only for arctic taxa. Five arctic Pedicularis are annuals or biennials, life forms otherwise rare in the Arctic. Other genera of the Orobanchaceae consist also of an elevated number of short-lived species, thus hemiparasitism may favor this life form in the Arctic.

Titov: Mycocaliciale Pilze der Holarktis - Übersetzung der Bestimmungsschlüssel und Beschreibungen neuer Arten

Zusammenfassung: Stordeur, R., Braun, U. & Tkach, N. 2010. Titov: Mycocaliciale Pilze der Holarktis — Übersetzung der Bestimmungsschlüssel und Beschreibungen neuer Arten. — Herzogia 23: 19–67. Es wird eine Übersetzung aller in dem im Jahre 2006 in Russisch erschienenen Buch von A. N. Titov: „Mycocaliciale Pilze der Holarktis” vorhandener Schlüssel in Deutsch und Englisch vorgelegt, ergänzt durch eine Liste aller im Buch behandelter Taxa. Zusätzlich werden Übersetzungen der Texte der neun von Titov neu beschriebenen Arten, der nomenklatorische Teil einer dort vorgeschlagenen Neukombination, sowie der Texte aller Arten mit ungeklärter systematischer Stellung und der von Titov ausgeschlossenen Taxa aufgeführt.