Wetland-Archaeology in the Alpine Space. Overview and actual research issues.

First indications of prehistoric sites in lakes of Switzerland go back more than 200 years and in 1854 Ferdinand Keller (1800-1881) published his famous book The Celtic Pile Dwellings in Swiss Lakes. Since these times, large-scale rescue excavations as well as survey and research projects have extended our knowledge about Neolithic and Bronze Age settlements in lakes, bogs and rivers around the European Alps. In 2011 a representative choice of 111 sites out of nearly 1000 in six countries around the Alps (Austria, France, Germany, Italy, Slovenia and Switzerland) were recognized by the UNESCO World Heritage committee as serial World Heritage. The lecture will give a general overview on prehistoric lake dwellings around the Alps (distribution, types of lakes/bogs and environment of sites, chronology/cultural units in the time scale 5300 to 800 BC) and present examples of well-documented settlement structures. The intense use of dendrochronological dating allowed the building up of a well-fixed chronological framework. In some cases dendrochronology is the basis for year-by-year reconstructions of prehistoric village biographies and detailed insights in the life cycle of early agrarian settlements. Beside these local events the grouped repartition of lake dwelling remains on the time scale makes a more global correlation between Holocene lake levels and the preservation of archaeological layers likely.

Analysis of llicit and illicit drugs in waste, surface and lake water samples using large volume direct injection high performance liquid chromatography – Electrospray tandem mass spectrometry (HPLC–MS/MS)

http://www.sciencedirect.com/science/article/pii/S0045653510008891

Patterns of morphological changes and hybridization between sympatric whitefish morphs (Coregonus spp.) in a Swiss lake: a role for eutrophication?

Whitefish, genus Coregonus, show exceptional levels of phenotypic diversity with sympatric morphs occurring in numerous postglacial lakes in the northern hemisphere. Here, we studied the effects of human-induced eutrophication on sympatric whitefish morphs in the Swiss lake, Lake Thun. In particular, we addressed the questions whether eutrophication (i) induced hybridization between two ecologically divergent summer-spawning morphs through a loss of environmental heterogeneity, and (ii) induced rapid adaptive morphological changes through changes in the food web structure. Genetic analysis based on 11 microsatellite loci of 282 spawners revealed that the pelagic and the benthic morph represent highly distinct gene pools occurring at different relative proportions on all seven known spawning sites. Gill raker counts, a highly heritable trait, showed nearly discrete distributions for the two morphs. Multilocus genotypes characteristic of the pelagic morph had more gill rakers than genotypes characteristic of benthic morph. Using Bayesian methods, we found indications of recent but limited introgressive hybridization. Comparisons with historical gill raker data yielded median evolutionary rates of 0.24 haldanes and median selection intensities of 0.27 for this trait in both morphs for 1948-2004 suggesting rapid evolution through directional selection at this trait. However, phenotypic plasticity as an alternative explanation for this phenotypic change cannot be discarded. We hypothesize that both the temporal shifts in mean gill raker counts and the recent hybridization reflect responses to changes in the trophic state of the lake induced by pollution in the 1960s, which created novel selection pressures with respect to feeding niches and spawning site preferences.

Female mating preferences and male coloration covary with water transparency in a Lake Victoria cichlid fish

Rapid speciation in Lake Victoria cichlid fish of the genus Pundamilia may be facilitated by sexual selection: female mate choice exerts sexual selection on male nuptial coloration within species and maintains reproductive isolation between species. However, declining water transparency coincides with increasingly dull coloration and increasing hybridization. In the present study, we investigated the mechanism underlying this pattern in Pundamilia nyererei, a species that interbreeds with a sister species in turbid but not in clear water. We compared measures of intraspecific sexual selection between two populations from locations that differ in water transparency. First, in laboratory mate-choice experiments, conducted in clear water and under broad-spectrum illumination, we found that females originating from turbid water have significantly weaker preferences for male coloration than females originating from clear water. Second, both the hue and body coverage of male coloration differ between populations, which is consistent with adaptation to different photic habitats. These findings suggest that the observed relationship between male coloration and water transparency is not mediated by environmental variation alone. Rather, female mating preferences are indicated to have changed in response to this variation, constituting the first evidence for intraspecific preference-trait co-evolution in cichlid fish. (C) 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99, 398-406.

No evidence for a genetic association between female mating preference and male secondary sexual trait in a Lake Victoria cichlid fish

Sexual selection by female mating preference for male nuptial coloration has been suggested as a driving force in the rapid speciation of Lake Victoria cichlid fish. This process could have been facilitated or accelerated by genetic associations between female preference loci and male coloration loci. Preferences, as well as coloration, are heritable traits and are probably determined by more than one gene. However, little is known about potential genetic associations between these traits. In turbid water, we found a population that is variable in male nuptial coloration from blue to yellow to red. Males at the extreme ends of the phenotype distribution resemble a reproductively isolated species pair in clear water that has diverged into one species with blue-grey mates and one species with bright red males. Females of the turbid water population vary in mating preference coinciding with the male phenotype distribution. For the current study, these females were mated to blue males. We measured the coloration of the sires and male offspring. Parents-offspring regression showed that the sires did not affect male offspring coloration, which confirms earlier findings that the blue species breeds true. In contrast, male offspring coloration was determined by the identity of the dams, which suggests that there is heritable variation in male color genes between females. However, we found that mating preferences of the dams were not correlated with male offspring coloration. Thus, there is no evidence for strong genetic linkage between mating preference and the preferred trait in this population [Current Zoology 56 (1): 57-64 2010].

Identification of candidate genes and physiological pathways involved in gonad deformation in whitefish (Coregonus spp.) from Lake Thun, Switzerland

In 2000, fishermen reported the appearance of deformed reproductive organs in whitefish (Coregonus spp.) from Lake Thun, Switzerland. Despite intensive investigations, the causes of these abnormalities remain unknown. Using gene expression profiling, we sought to identify candidate genes and physiological processes possibly associated with the observed gonadal deformations, in order to gain insights into potential causes. Using in situ-synthesized oligonucleotide arrays, we compared the expression levels at 21,492 unique transcript probes in liver and head kidney tissue of male whitefish with deformed and normally developed gonads, respectively. The fish had been collected on spawning sites of two genetically distinct whitefish forms of Lake Thun. We contrasted the gene expression profiles of 56 individuals, i.e., 14 individuals of each phenotype and of each population. Gene-by-gene analysis revealed weak expression differences between normal and deformed fish, and only one gene, ictacalcin, was found to be up-regulated in head kidney tissue of deformed fish from both whitefish forms, However, this difference could not be confirmed with quantitative real-time qPCR. Enrichment analysis on the level of physiological processes revealed (i) the involvement of immune response genes in both tissues, particularly those linked to complement activation in the liver, (ii) proteolysis in the liver and (iii) GTPase activity and Ras protein signal transduction in the head kidney. In comparison with current literature, this gene expression pattern signals a chronic autoimmune disease in the testes. Based on the recent observations that gonad deformations are induced through feeding of zooplankton from Lake Thun we hypothesize that a xenobiotic accumulated in whitefish via the plankton triggering autoimmunity as the likely cause of gonad deformations. We propose several experimental strategies to verify or reject this hypothesis.