International Association for Lichenology

Silke Werth

Silke Werth

This year’s Mason Hale award goes to Silke Werth for her dissertation, “Dispersal and persistence of an epiphytic lichen in a dynamic pasture-woodland landscape.” Silke is an ecologist/conservation biologist that is equally comfortable in the field working under harsh conditions in the snow, in the lab doing molecular studies on degenerated DNA, and on the computer developing simulation programs to test hypotheses about ecological processes in a forest-dominated landscape.

Tourists who spot Silke somewhere in the field, collecting several hundred kilograms of snow in a forest in the middle of nowhere would probably agree that the person must be a scientist – no normal person would do something similar. But nobody would guess that this researcher is a botanist, a mycologist or, in fact, the ideal synthesis of the two disciplines – a lichenologist. The material being sought in the snow is smaller than the famous needle in the haystack; it is a diaspore in the landscape. But Silke managed to detect the quasi-nothing in the lab and to build a model to show how a rarely seen lichen can disperse a few propagules in an endless forest in a way that allows the species to remain rare but, hopefully, not go extinct. In other words:

Silke Werth’s PhD dissertation is a significant contribution to the understanding of the population dynamics of endangered epiphytic lichen species. The thesis is extremely successful in disentangling a complex ecological problem: how a rare epiphytic lichen can disperse and persist in a dynamic, highly structured landscape of Medieval origin. Her studies involved a multitude of methodologies including molecular techniques that allowed her to detect diaspores of the target species in complex litter samples, microsatellite analyses to investigate the diversity and differentiation of local demes of an epiphytic lichen, as well as transplants of lichen fragments and diaspores to study the potential distribution of the species in a topographically complex landscape.

This outstanding student established a very successful collaboration with a spatial ecologist that allowed her to make a significant contribution to the theoretical analysis of spatial genetic structures of continuous populations. This approach has considerable advantages over the traditionally used calculation of correlograms such as Moran’s I and allowed her to address gene flow at the landscape level and thus to make a substantial contribution to landscape genetics, a promising field that integrates landscape ecology and population genetics.

Most studies of population genetics involve spatially segregated populations at large scales. There is very little information on landscape-level organisation of genetic variability and gene flow patterns despite its potential importance for population conservation and persistence. The PhD thesis included five papers of which four have been published or are now in press; one paper is under review.

Silke did her PhD at the University of Berne in the lab of Christoph Scheidegger at the Swiss Federal Research Institute for Forest, Snow and Landscape Research in Birmensdorf, Switzerland. At present, she is on a postdoctoral fellowship at Victoria Sork’s lab at the University of California, Los Angeles. In her new position Silke is studying the phylogeography of Ramalina menziesii.

Christoph Scheidegger