Institute of Botany
Sect. Plant Ecology
Kolloquien des Botanischen Instituts
In der Regel Donnerstag, 17.15 - 18.00 Uhr (mit anschliessender Diskussion)
Ort: Hörsaal des Botanischen Instituts, Schönbeinstrasse 6, 4056 Basel
Do. 22. September 2011 • 17.15 Uhr
Geographical variation in population biology and genetic structure of the alpine thistle Carduus defloratus
Dipl. Biol. Andrea Vaupel, Philipps-Universität Marburg, Deutschland
Biologists have long been fascinated by the ecological and evolutionary processes at speciesˈ range limits. On changing conditions, plant species may response with local adaptation, phenotypic plasticity or extinction. Studies that compare populations from the centre and the periphery of the distribution of a species may help to understand the behaviour of populations along gradients of increasing environmental stress and the response of plant species to climate change. An important biogeographical model, the abundant centre model (ACM), predicts that because of increasingly unfavourable conditions populations become less frequent, smaller, less dense, and less reproductive towards the range edges. Genetic diversity of peripheral populations is predicted to be lower, while the genetic differentiation between populations should be larger.
In an extensive study of Carduus defloratus (Asteraceae) along a latitudinal and altitudinal gradient across Central Europe, we investigated whether population performance and genetic diversity declines from the distribution centre to the periphery. We also studied the relative importance of latitude and altitude for the variation in population characteristics, plant traits and seed-predation. The comparative analysis of peripheral and central populations strongly supports the predictions of the ACM. However, the differences variation in population characteristics, individual plant traits and seed-predation among populations were better explained by altitude than by latitude. Interestingly, pre-dispersal seed predation increased with altitude, which may be due to increasing plant population sizes. Plant height and specific leaf area decreased with altitude, indicating that populations of the alpine thistle respond with phenotypic plasticity or local adaptation to environmental gradients. The differences in genetic structure between populations were better explained by latitude than by altitude and were to a large part due to isolation by distance. Postglacial range expansions and contractions may have influenced genetic diversity, genetic structure and population performance of the alpine thistle.
In an extensive study of Carduus defloratus (Asteraceae) along a latitudinal and altitudinal gradient across Central Europe, we investigated whether population performance and genetic diversity declines from the distribution centre to the periphery. We also studied the relative importance of latitude and altitude for the variation in population characteristics, plant traits and seed-predation. The comparative analysis of peripheral and central populations strongly supports the predictions of the ACM. However, the differences variation in population characteristics, individual plant traits and seed-predation among populations were better explained by altitude than by latitude. Interestingly, pre-dispersal seed predation increased with altitude, which may be due to increasing plant population sizes. Plant height and specific leaf area decreased with altitude, indicating that populations of the alpine thistle respond with phenotypic plasticity or local adaptation to environmental gradients. The differences in genetic structure between populations were better explained by latitude than by altitude and were to a large part due to isolation by distance. Postglacial range expansions and contractions may have influenced genetic diversity, genetic structure and population performance of the alpine thistle.