Darwin and the plants of the Galapagos-Islands

During his five year sea voyage with the “Beagle”, Darwin, at the suggestion of the botanist J.S. Henslow, collected more than 1400 vascular plants, and more than 200 of them alone during his short stay on the Galápagos Islands. The unique collection of plants from the Galápagos archipelago was examined in 1845 by J.D. Hooker. Unlike the birds, Darwin had collected the plants separately for each island. Hooker described 78 of them as new species and analyzed the close biogeographical relations of the Galápagos flora with the South-American continent. The finding that more than 50% of the species are not found anywhere else on the globe – are hence endemics, many of them restricted to individual islands – was a sensation for Hooker and Darwin. Hooker correctly characterized the Asteraceae as the most remarkable family of the Galápagos Islands, due to the great number of their endemic genera and species. He also discussed the adaptations which might have allowed the plants of the different families to reach the isolated islands. Hooker’s results played an important role for Darwin in his developing the theory of evolution, and – besides the examples of birds, tortoises, and lizards – provided him with weighty arguments to defend it. There are seven endemic plant genera on the Galápagos Islands, and 19 genera that are adaptively diversified. With 19 endemic taxa, the genus Scalesia (Asteraceae) is the most spectacular example of an adaptive radiation, followed by the prickly pear cactuses (Opuntia) with 14 endemic taxa. While Darwin’s finches meanwhile represent one of the best-studied examples of evolution and adaptive radiation, only little research has been done so far into evolutionary processes in plants of the Galápagos archipelago. The prominent role that Darwin’s plants played for his scientific insights is even less known

Differences in life history traits of related Epilobium species: Clonality, seed size and seed number

Small changes in morphology can affect the performance and functions of organisms and hence their ecological success. In modular constructed plants, contrasting growth strategies may be realized by differences in the spatial arrangement and size of shoots. Such differences change the way in which meristems and resources are assigned to various functions during the lifespan of a plant. If such changes include the capacity to spread clonally, sexual reproduction may also be affected. I compare patterns in vegetative growth and sexual reproductive traits in four allopatric species ofEpilobium which are sometimes considered as subspecies of a single polymorphic taxon. The four species differ in the location of the buds which annually renew the aerial shoot system.E. dodonaei andE. steveni do not spread clonally and are characterized by a shrub-like habit.E. fleischeri, a species occurring only in the Alps, andE. colchicum, which occurs in the upper region of the Caucasus mountains, both produce buds on horizontal roots or plagiotropic shoots. Both alpine species exhibiting clonal growth have smaller shoots, fewer fruits and smaller seeds than the lowland species. An intraspecific trade-off between seed number per fruit and seed mass is realized. Both alpine species produce more seeds per fruit at the expense of seed mass. The morphological relationship between the four species and their geographical distribution suggest that clonal growth inE. fleischeri (restricted to the Alps) andE. colchicum (restricted to the Caucasus) is adaptively associated with the stressful conditions of alpine habitats. Our results suggest that clonal growth is not necessarily correlated with reduced reproduction by seeds. The success of plants which are already established may largely depend on clonal spread, but the colonization of new habitats depends on the production of a large number of small seeds with high dispersabilit

Evolution der Gattung Echium auf den Kanarischen Inseln: vom Kraut zum Strauch zum Rosettenbaum

The genus Echium is represented on the seven volcanic Canary islands by 24 closely related endemic species. As in other genera on the archipelago, the diversityin Echium is a result of rapid adaptive radiation during the last few million years. Withmolecular markers, the evolution of Echium on the Canary Islands can be traced backto a single colonisation event. In contrast to Echium species on the continent, most ofthe insular endemics are woody perennials. Some of the more spectacular species aregiant rosette trees that flower only once and then die. The evolutionary diversificationin Echium results from the drastic climatic changes in the past, from the climatic andedaphic diversity of habitats, and from genetic bottleneckevents during the colonisationof newly formed volcanic islands. Today, the predominance of woodiness inendemic island species is explained by selection for longevity due to the scarcity ofpollinators. The red-flowered E. wildpretii occurring in the volcanic Caldera of the highestmountain on Tenerife, Pico el Teide, is the most spectacular giant rosette tree ofthe archipelago and is pollinated by an endemic bird. From molecular studies the phylogeneticrelationship among Echium species are well known. Their ecology, however,needs to be better explored in order to protect them from harmful consequences ofhabitat destruction and climatic change

Informations- und Kommunikationskompetenz – das «Lesen und Schreiben» der ICT-Kultur

Nach der Schrift und dem Buchdruck führen gegenwärtig die elektronischen Medien zu einem dritten grossen Leitmedienwechsel. Ein solcher Leitmedienwechsel führt jeweils zu starken Veränderungen der Kultur. Gemäss Hans Magnus Enzensberger orientiert sich eine neue Kultur zu Beginn immer an der alten, erst später wird sie selbständig und baut einen eigenen Charakter auf. So stammt das Verständnis der Informationskompetenz aus Zeiten, in denen das Buch das Leitmedium war. Massnahmen zur Förderung des kompetenten Umgangs mit Informationen besonders in Bibliotheken sowie Evaluationen der Informationskompetenz von Schülerinnen und Schülern oder von Studierenden basieren auf diesem Verständnis und entsprechenden Modellen. Der aktuelle Leitmedienwechsel von einer vom Buch geprägten Kultur zu einer von Informations- und Kommunika­tionstechnologien (ICT) – allen voran dem Internet – dominierten Kultur macht ein neues Verständnis der Informationskompetenz notwendig. Im vorliegenden Text werden eine neue Definition, neue Standards und mögliche aktuelle Inhalte zur Förderung von Informationskompetenz systematisch aus kommunikationstheoretischen und soziologischen Betrachtungen des Leitmedienwechsels hergeleitet. Bislang stand bei der Förderung von Informationskompetenz die Rezeption von Texten im Vordergrund. Neu sind dem die Produktion und Übermittlung von Ton-Dokumenten, Videos, Fotos, Grafiken sowie Animationen gleichzustellen. Damit nähert sich der Begriff «Informationskompetenz» stark jenen der Medienkompetenz und der ICT-Kompetenz an

Flora der Furka

The Furka is an Alpine pass at 2431 m a.s.l. connecting the Urseren Valley and the Rhone Valley in the central Swiss Alps. Furthermore, the Furka is the watershed between the Mediterranean and the North Sea. The region is mostly characterized by siliceous rocks and acid soils, but calcareous sediments are also present. Here, the floristic composition and the plant communities of the Furka Region are described from a survey of 181 vegetation records covering all types of habitats, bedrocks, soils, slopes and expositions. In total 295 species, 153 genera and 49 plant families are represented in the Furka flora. The vegetation is composed of a diversity of mostly non-woody plant communities. Natural grasslands with Carex curvula and Nardus stricta on acid soils and with Festuca violacea on calcareous bedrock are most abundant. Grassland together with fens, dwarf shrubs, and plant communities from rock debris, screes, and glacier foreland create a diverse mosaic of alpine vegetation above timberline

Flowering phenology and reproductive fitness along a mountain slope: maladaptive responses to transplantation to a warmer climate in Campanula thyrsoides

In many biomes, global warming has resulted in advanced and longer growing seasons, which has often led to earlier flowering in plant taxa. Elevational gradients are ideal to study the effects of global warming as they allow transplantation of plants from their original cooler higher elevations down to elevations with a prospective climate. We transplanted plants from ten populations of the European alpine monocarpic herb species Campanula thyrsoides L. to three sites along a steep mountain slope (600, 1,235 and 1,850m above sea level) in the Swiss Alps and asked whether reproductive phenology adjusts plastically to elevation and if these responses were adaptive, i.e. increased the fitness of plants. We further assessed current genetic differentiation in phenotypic traits and whether any such origin effects were due to adaptation to climatic conditions of origin. Our results showed that transplantation to lower elevations caused strong shifts in phenology, with plants starting growth and flowering earlier than plants placed at higher elevations. However, compared to flower production at high elevation, number of flowers per plant decreased 21% at mid- and 61% at low elevation. The shift in phenology thus came with a high cost in fitness, and we suggest that phenology is maladaptive when C. thyrsoides faces temperature conditions deviating from its natural amplitude. We conclude that the frequently reported phenological shift in plant species as a response to global warming may include heavy fitness costs that may hamper species surviva

Does pre-dispersal seed predation limit reproduction and population growth in the alpine clonal plant Geum reptans ?

We studied the impact of the seed damaging gall midge larva Geomyia alpina on its perennial alpine host plant Geum reptans. We analysed the effect of seed predation on reproduction by seeds, i.e. seed number, seed mass, and seed viability and on growth and clonal propagation of non-protected plants in comparison to plants protected from predation by an insecticide. Additionally, we assessed the consequences of seed predation for population growth using matrix projection modelling. Seed predation resulted in a decrease in total seed mass per flower head by 23.8% in non-protected plants (P<0.05). Individual seed mass decreased with increasing infestation intensity (P<0.05). Seed number remained unaffected because the sucking feeding behaviour by gall midge larvae does not evoke seed abortion. Percent germination of seeds from non-protected plants was reduced by 97.9% compared to seeds from protected plants. According to reduced seed viability, modelling revealed a decrease in population growth rate from λ=1.055 to λ=1.041. Predation did neither influence total plant biomass nor biomass fractions. But stolon dry-weight of non-protected plants increased by 24.1% (P<0.05), which may indicate a trade-off between sexual reproduction and clonal propagation. Our results demonstrate that despite substantial reduction of viable seeds, predation by gall midge larvae only slightly affected population growth of G. reptans suggesting that in this alpine species, persistence by longevity and clonal propagation can balance potential seed losses by predation, at least for local population growt