The Genus Avenula (Dumort.) Dumort., Poaceae, on the Balkan Peninsula

Von den im vorliegenden Beitrag näher behandelten Gattungen Avenula und Helictotrichon sind die tetraploiden Arten A. blavii und A. aetolica (2n = 28) sowie der dekaplo- ide Sippen-Komplex von A. cycladum s.l. (2n = ± 70) ausschließlich auf die Balkanhalbinsel bzw. auf die südägäi- schen Inseln beschränkt, wo sie entweder in den Gebirgen (A. blavii, A. aetolica) oder in der mediterranen Stufe (A. cycladum) Vorkommen. — Von den diploiden Arten mit 2n = 14 ließ sich H. convolutum s.l. mit Sicherheit aus der Zentral- und Ostmediterraneis nach weisen, während A. compressa im wesentlichen eine pontisch-pannonische Art repräsentiert. H. parlatorei und H. petzense bleiben auf die Alpen beschränkt, während A. versicolor sowohl in den Alpen als auch in den nordbalkanischen Gebirgen vorkommt. Die weiteste Verbeitung unter den Diploiden besitzt A. pubescens, und zwar im temperaten Europa und West- Asien. — A. adsurgens s.l. und A. praeusta sind hochpo- lyploid (2n = ± 126 bzw. 2n = ± 140 —154). Während das Verbreitungsgebiet der letzteren wohl ausschließlich in den (Ost-) Alpen liegt, kommt A. adsurgens von den östlichen Ostalpen bis Rumänien bzw. bis Jugoslawien und Bulgarien vor. A. planiculmis konnte noch nicht mit Sicherheit für das Gebiet nachgewiesen werden, A. pratensis s.l. scheint ihm vollständig zu fehlen. — Die Karyotypen der studierten Avenula- und Helictotrichon-Arten lassen auf eine weitgehend identische Entwicklung schließen. Die einjährigen Hafer der Gattung Avena dürften auf bereits karyologisch stärker abgeleitete Ausgangs-Sippen zurückzuführen sein.Uzevši u obzir kariološke podatke, možemo prikazati o istraživanim divljim vrstama zobi Balkanskog poluotoka i susjednih područja vrlo diferenciranu evolucijsku shemu. 1. Genomi obrađenih vrsta rodova Avenula i Helictotrichon upućuju na identične smjerove evolucije. Tako su se već na diploidnom stupnju ± asimetrični kariotipovi irazvili od ishodišnih ± simetričnih kariotipova. Slična diferencijacija zbila se unutar jednogodišnjih vrsta zobi (Avena) također na diploidnom stupnju (genomi B, C, D), no na osnovi već više odvedenih kariotipova, kao što je genom A koji se mogao također naći i kod trajnih dviljih zobi (Avenula compressa). Konačno su se u nekoliko područja skupine viših poliploida (trajnih) mogle razviti paralelno od diploida te od nižih poliploidnih vrsta (vidi si. 4 i 5). 2. Diploidne vrste zastupaju (2n = 14): Avenula pubescens, A. versi- color, A. compressa, Helictotrichon petzense i H. convolutum. A. blavii i A. aetolica su tetraploidi (2n = 28). Prvi put je nađen dekaploidni broj kromosoma (2n = ± 70). i to kod vrste A. cycladum. Visoki poliploidni kromosomski brojevi karakteriziraju vrste A. adsurgens (18x : 2n = ± 126) i A. praeusta (18x i 20x — 22x : 140— ± 154). 3. Unutar diploidnih vrsta zobi trajnica moguće je razlikovati dobro definirane vrste, koje su prisutne u gotovo svim područjima Balkanskog poluotoka. Široka rasprostranjenost u nizinama umjerenog klimatskog područja Evrope i zapadne Azije karakteristična je za Avenula pubescens, dok je A. compressa nađena u područjima oko zapadnog dijela Crnog mora. Prema jugu (jugoistoku) obje se vrste sve više penju u planine. Avenula versicolor i Helictotrichon parlatorei predstavljaju v|rste visokih planina Evrope. Uzevši u obzir njihovu ekološku adaptaciju na alpske livade ili siparišta vapnenačkih Alpa, njihovi su areali karakterizirani izrazitom disjunkcijom. Endemična vrsta Helictotrichon petzense nastanjuje vrlo malo područje u istočnim Karavankama i Kamniškim Alpama. H. convolutum predstavlja vrstu kamenih i pješčanih staništa u eu- mediteranskom području od Sicilije do Grčke (i vjerojatno Turske?). 4. Tetraploidne vrste Avenula blavii i A. aetolica obilježene su kao endemske vrste centralnih odnosno južnih planina Balkanskog poluotoka. 5. U prošlosti visoko poliploiđne vrste bile su zamjenjivane. One imaju težišta u tri dobro ograničena područja: Avenula cycladum s.l. predstavlja skupinu mikrospecijesa u obalnom području južnog dijela Egejskog mora s jako ¡raskidanim arealoim. A. adsurgens je tipična vrsta kontinentalnih područja istočnog dijela istočnih Alpa do Transilvanije, no ona nedostaje u nizinskom dijelu Madžarske. Po našem sadašnjem shvaćanju A. praeusta vjerojatno predstavlja vrstu alpskih livada istočnog dijela južnih Alpa. 6. Vrsta Avenula pratensis i vrsta A. planiculmis vrlo su često bile zamjenjivane s drugim vrstama. Čini se da ih na Balkanskom poluotoku nema.Karyological data show a very differentiated pattern of evolution for wild oats of the Balkan Peninsula and adjacent territories 1. The genomes of the species discussed far Avenula and Helictotrichon suggest identical trends of their evolution. Already on the diploid level, mor or less asymmetric karyotypes have evolved probably from more or less original and symmetrical ones. — A similar differentiation has happened within the annual oats (Avena) also on the diploid level (genome B, C, D), but on the basis of already more advanced karyotypes, such as genome A, which could also be found in perennial oats (A. com- pressa). — Finally in several regions high polyploid groups of (perennial) oats have evolved parallelly from diploid and/or lower polyploid species (s. figs. 4 and 5). 2. The diploid species (2n = 14) are represented by Avenula pubes- cens, A. versicolor, A. compressa, Helictotrichon parlatorei, H. petzense, and H. convolutum. — A. blavii and A. aetolica are tetraploid (2n = 28). — For the first time a decaploid chromosome number (2n = ± 70) has been found in A. cycladum. — High polyploid chromosome numbers characterize A. adsurgens (18x: 2n = ± 126), and A. praeusta (18x and 20x — 22x: ± 140 — ± 154). 3. Within the diploid species of the perennial oats well defined groups of species can be distinguished, which are present in nearly all regions of the Balkan Peninsula: A wide distribution in the lowlands of temperate Europe and West-Asia is characteristic of Avenula pubes- cens, while A. compressa is found in the regions around the western part of the Black Sea. To the south(east) both species ascend more and more into the mountains. — Avenula versicolor and Helictotrichon parlatorei represent species of the European high mountains. With respect to their ecological adaptation to alpine meadows or to screes of the Limestone Alps their areas are characterized by a marked disjunction. — Endemic H. petzense occupies a very small area in the eastern Kara- wanken and in the Steiner Alpen. — H. convolutum represents a species of rocky and sandy habitats of the eumediterranean region from Sicily to Greece (and, probably, of Turkey). 4. The tetraploid species Avenula blavii and A. aetolica are characterized as endemic species of the central and/or southern mountains of the Balkan Peninsula. 5. High polyploid species have often been wrongly interpreted. They are centered on three well circumscribed regions: Avenula cycladum s.l. represents a group of microspecies in the South Aegean Sea, with a highly splitted area. A. adsurgens is a typical species of continental regions from the eastern East-Alps to Transylvania, but lacking in the Hungarian Lowlands. — According to our present knowledge, probably, A. praeusta represents a species of alpine meadows of the eastern South- Alps. 6. Very often Avenula pratensis and A. planiculmis have been confused with other species. They seem to be absent from the Balkan Peninsula

The Role of Meson Retardation in the NN Interaction above Pion Threshold

A model is developed for the hadronic interaction in the two-nucleon system above pion threshold which is based on meson, nucleon and $\Delta$ degrees of freedom and which includes full meson retardation in the exchange operators. For technical reasons, the model allows maximal one meson to be present explicitly. Thus the Hilbert space contains besides $NN$ and $N\Delta$ also configurations consisting of two nucleons and one meson. For this reason, only two- and three-body unitarity is obeyed, and the model is suited for reactions in the two nucleon sector only, where one pion is produced or absorbed. Starting from a realistic pure nucleonic retarded potential, which had to be renormalized because of the additional $\pi$ and $\Delta$ degrees of freedom, a reasonable fit to experimental $NN$-scattering data could be achieved.Comment: 30 pages revtex including 17 figures, outline of model and discussion shortened, typos correcte

Codex diplomaticus Nassoicus = Nassauisches Urkundenbuch

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akzeptierte Manuskriptversio

Rescattering effects in coherent pion photoproduction on the deuteron in the Δ\Delta resonance region

Within a dynamical model, rescattering effects are studied in coherent pion photoproduction on the deuteron in the $\Delta$(1232) resonance region. The model consists of a system of coupled equations for the N$\Delta$, NN$\pi$ and NN channels. Pion rescattering leads in general to a significant reduction of total and differential cross sections resulting in a better description of experimental data. Only a few polarization observables are sensitive to rescattering effects. In particular $T_{20}$ allows an analysis of the reaction mechanism for specific kinematics. The question how rescattering affects the sensitivity to the E2 excitation of the $\Delta$ resonance is also studied.Comment: 28 pages revtex including 12 postscript figure