University, Diss., 2005--Bonn.

Techn. University, Diss., 2007--Darmstadt.

University, Diss., 2001--Kiel.

Naturvidenskabelige doktorgrad--Naturvidenskabelige Fakultet--Københavns Universitet, 2006. / Contient un texte en anglais et son résumé en danois. Bibliogr. p. 127-136.

No description available.

Les pelouses alpines à Carex curvula (laîche courbée) constituent l'une des formations les plus emblématiques de l'étage alpin des montagnes européennes. Cette thèse se présente comme une contribution à l'étude des patrons de la diversité génétique de Carex curvula et des patrons de la diversité floristique des pelouses alpines à Carex curvula en Europe.<br /> Dans un premier temps, ce travail examine la variabilité floristique des pelouses dominées par C. curvula et tente d'identifier les forces qui ont joué le rôle le plus important dans la structuration des espèces de l'étage alpin acidiphile européen. Les résultats des analyses montrent qu'il existe une variabilité importante pour la distribution de la diversité interspécifique et seulement une correspondance partielle entre la position des barrières biogéographiques de l'étage alpin et les grandes distances géographiques qui séparent les massifs montagnards. Il ressort nettement que les forces qui ont joué le rôle le plus important dans la structuration floristique de l'étage alpin acidiphile européen sont de nature historique et dans une moindre mesure de nature écologique.<br /> Ensuite, nous explorons la distribution de la diversité génétique dans les populations de C. curvula dans un contexte phylogéographique. L'impact des glaciations quaternaires correspond à deux histoires différentes pour les flores alpines dans les montagnes de l'ouest et de l'est du continent européen. Chez C. curvula, les mécanismes de recolonisations postglaciaires auraient impliqué un large vague de migration est-ouest dans les Alpes et une migration verticale beaucoup plus locale dans les Carpates. Les Pyrénées auraient été colonisé plus récemment, à partir d'un refuge secondaire localisé dans les Alpes du Sud-Ouest.<br /> Enfin, dans un troisième temps, nous nous intéressons au problème des relations entre la diversité génétique et floristique, en analysant la diversité locale des espèces dans les pelouses à C. curvula et la diversité génétique de l'espèce dominante. Le manque de corrélation positive entre les deux niveaux de la diversité est expliqué par des réponses différentes des gènes et des espèces aux grands changements climatiques qui sont intervenus au cours du Quaternaire.<br /> Nous concluons sur les perspectives de biogéographie comparative ouvertes par ce travail, en particulier sur l'articulation souhaitée entre les efforts de modélisation de la distribution biologique, la phylogéographie et l'écologie évolutive.

The Aristolochiaceae are one of the largest angiosperm families, the family has been divided into two subfamilies: Asaroideae, which include Asarum and Saruma, and Aristolochioideae, which includes Thottea sensu lato and Aristolochia sensu lato (Kelly and Gonzales, 2003). Aristolochia sensu lato comprise between 450 and 600 species, distributed throughout the world with centers of diversities in the tropical and subtropical regions (Neinhuis et al., 2005, Wanke et al., 2006a, 2007). However, the extended Mediterranean region including Turkey, the Caucasus and the Near East is likely to be the only diversity hotspot of the genus Aristolochia in the northern hemisphere were up to 60 species and subspecies could be observed (Wanke 2007). Most important contributions to the knowledge of these species were published by Nardi (1984, 1988, 1991, 1993) and Davis &amp; Khan (1961, 1964, 1982), all of these studies were based on morphological characters only. In recent years, with the progress of molecular techniques and in light of the systematic chaos, a detailed study was needed to unravel the evolutionary history prior to a taxonomic revision of this group. The first chapter of my thesis should be regarded as the starting point for more detailed investigation on population level. Preliminary molecular phylogenitic analysis recovered the Mediterranean Aristolochia species as monophyletic (de Groot et al 2006). However, only very few members were included in that study. The latest phylogenetic study by Wanke (2007) dealed with west Mediterranean Aristolochia species and sampled also few members belonging to the east Mediterranean and Caucasian species (3 from Greece, 2 from Georgia and 1 from Turkey). This study reported the Mediterranean Aristolochia species as two molecular and morphologically well supported clades, which were sister to each other. Furthermore, the two closely related species A. sempervirens and A. baetica which have an east west vicariance and are known as Aristolochia sempervirens complex has been recovered as sister group to the remaining west Mediterranean species. A detailed investigation of the evolutionary history of this group is the topic of the second chapter of my thesis (Chapter 2). The Aristolochia sempervirens complex is characterized by an unusual growth form and has a circum Mediterranean distribution. The investigation of these species complex seem to be of great importance to understand speciation and colonization of the Mediterranean by the genus Aristolochia and might shade light in historical evolutionary processes of other plant lineages in the Mediterranean. Furthermore, I test applicability and phylogenetic power of a nuclear single copy gene (nSCG) region to reconstruct well resolved and highly supported gene genealogies as a prerequisite to study evolutionary biology questions in general. Furthermore, a comprehensive overview of leaf epicuticular waxes, hairs and trichomes of 54 species from the old and new world taxa of the genus Aristolochia were investigated using scanning electron microscopy (SEM) to clarify taxonomic status of theses species in contrast to their molecular position. Also this study which is the third chapter of this thesis (Chapter 3), has a strong focus on Mediterranean Aristolochia and tries to provide additional support for molecular findings based on epicuticular waxes and to test them as synapomorphies. Each chapter has its own introduction and abstract resulting in a short general introduction here.

Da limnische Gastropoden eng an ihre isolierten aquatischen Habitate gebunden sind, bewahren sie Verbreitungsmuster über lange Perioden und stellen geeignete Modelle zur Rekonstruktion geographisch und klimatisch bedingter Veränderungen des Lebensraumes dar. Das Ziel dieser Arbeit besteht in der Rekonstruktion der Besiedlungsgeschichte des australischen Kontinents durch eine Familie Süßwassergastropoden (Thiaridae) unter Verwendung molekularer Marker (mitochondrialer und im Kerngenom basierter Genfragmente inklusive der AFLP-Technik). Viele der heute in Australien vorkommenden biotischen Elemente wurden als junge Einwanderer aus dem indo-malayischen Archipel eingestuft. Es werden jedoch immer mehr Fälle bekannt, die von diesem Standardszenario abweichen. Um zu testen, ob es sich bei Thiariden tatsächlich um Einwanderer aus dem Norden handelt, oder ob ihr Ursprung auf dem australischen Kontinent liegt, wurden die evolutionären Verwandtschaftsverhältnisse innerhalb der Familie, sowie ihre Position im phylogenetischen Stammbaum der Superfamilie Cerithioidea analysiert. Mit der Aufdeckung der stammesgeschichtlichen Beziehungen zu nicht-australischen Verwandten, durch Altersbestimmung der phylogenetischen Verzweigungen mittels „molekularer Uhr“ sowie der detaillierten Analyse der aktuellen Vorkommnisse und möglichen historischen Areale, konnte ein asiatischer Ursprung der Thiariden widerlegt werden. Ein Abriss hinsichtlich Dispersion und/oder Vikarianz ist hier vor dem Hintergrund der Rekonstruktion plattentektonischer Ereignisse dargestellt. Demnach hat die Besiedlung Asiens ihren Ausgang ursprünglich im australischen Raum genommen und der Kontinent wurde nicht wie bislang angenommen von Asien aus besiedelt. Mit der Aufdeckung eines gondwanischen Ursprungs repräsentieren Thiariden ein vielversprechendes Modellsystem in der Speziationsforschung, welches Einblicke in die Dynamik der Mechanismen der Artbildung unter dem Einfluss von klimatischen Veränderungen ermöglicht. / Due to their limited potential of dispersal and habitat fidelity, limnic gastropods tend to preserve distribution patterns over long periods of time and are suitable organisms in biogeographical research. In this thesis intensive investigations into the phylogeography of Australian freshwater snails are provided, presenting the first molecular study of the Thiaridae (Caenogastropoda: Cerithioidea) based on DNA sequence markers and amplified fragment length polymorphisms. The aim of this study is to determine the historical events that may have influenced their presence on the Australian continent. In general, the origin of Australian freshwater faunal elements and the directionality and timing of colonizations are still controversial. Conventionally, many biotic elements found in Australia today are considered to be recent invaders from the Indo-Malay archipelago but more and more cases have become known that deviate from this standard scenario. In order to test whether the thiarids represent recent invaders or if they originated on the Australian continent, the evolutionary relationships within the family as well as its phylogenetic position in the superfamily Cerithioidea is analysed. A molecular clock approach is applied so that the dispersal events can be related to historical tectonical changes. By comparison of the molecular phylogenies, as well as the distributional data, the fossil record and divergence date estimates in conjunction with the excellent record of Earth history the long-held view that the thiarid fauna is an appendage to the southeast Asian biota can be rejected. Instead, an Australian continental, i.e. East-Gondwanian origin is found to be the most parsimonious explanation of the present distribution. With their now assumed long history on the continent, thiarids represent an important model system in speciation research which provides details of the dynamics of the underlying mechanisms of speciation under the influence of climate change.

No description available.

The present study deals with the largely unknown Peperomia subgenus Tildenia. Chapter 1 focuses on the South American centre of Tildenia biodiversity. Initially a general rectified description of Peperomia subgenus Tildenia is presented based on the latest molecular analyses. Fourteen new species are described together with two formerly published varieties that are raised to species rank. Furthermore, for one name, basionym rejection and lectotypification are proposed. All valid species from the South American centre of diversity are treated in a phylogenetic framework. A comparable study of the North American centre of diversity is presented in Chapter 2 including a key to all Tildenia species from Mexico and Central America and the description of thirteen new species (one former variety). The new descriptions within this study doubles the species number of subgenus Tildenia. Chapter 3 is a biogeographical study comprising the whole distribution area revealing the place of origin and the age of Peperomia subgenus Tildenia. The appearance of the major lineages of the subgenus is examined against the background of orogeny and climate changes in the respective distribution areas, to retrace the evolutional driving forces of this plant group. In Chapter 4 Tildenia is used as a model group for the characterisation of a new nuclear single copy gene applicable for general use for phylogentic resoltution on species level and below.