Genetic and phenotypic population divergence on a microgeographic scale in brown trout.

Salmonid populations of many rivers are rapidly declining. One possible explanation is that habitat fragmentation increases genetic drift and reduces the populations' potential to adapt to changing environmental conditions. We measured the genetic and eco-morphological diversity of brown trout (Salmo trutta) in a Swiss stream system, using multivariate statistics and Bayesian clustering. We found large genetic and phenotypic variation within only 40 km of stream length. Eighty-eight percent of all pairwise F(ST) comparisons and 50% of the population comparisons in body shape were significant. High success rates of population assignment tests confirmed the distinctiveness of populations in both genotype and phenotype. Spatial analysis revealed that divergence increased with waterway distance, the number of weirs, and stretches of poor habitat between sampling locations, but effects of isolation-by-distance and habitat fragmentation could not be fully disentangled. Stocking intensity varied between streams but did not appear to erode genetic diversity within populations. A lack of association between phenotypic and genetic divergence points to a role of local adaptation or phenotypically plastic responses to habitat heterogeneity. Indeed, body shape could be largely explained by topographic stream slope, and variation in overall phenotype matched the flow regimes of the respective habitats.

Effect of biogeographic history on population vulnerability in European amphibians.

The genetic diversity of populations, which contributes greatly to their adaptive potential, is negatively affected by anthropogenic habitat fragmentation and destruction. However, continental-scale losses of genetic diversity also resulted from the population expansions that followed the end of the last glaciation, an element that is rarely considered in a conservation context. We addressed this issue in a meta-analysis in which we compared the spatial patterns of vulnerability of 18 widespread European amphibians in light of phylogeographic histories (glacial refugia and postglacial routes) and anthropogenic disturbances. Conservation statuses significantly worsened with distances from refugia, particularly in the context of industrial agriculture; human population density also had a negative effect. These findings suggest that features associated with the loss of genetic diversity in post-glacial amphibian populations (such as enhanced fixation load or depressed adaptive potential) may increase their susceptibility to current threats (e.g., habitat fragmentation and pesticide use). We propose that the phylogeographic status of populations (i.e., refugial vs. post-glacial) should be considered in conservation assessments for regional and national red lists.

Face à la fragmentation des savoirs et des pratiques : l'apport de l'anthropologie clinique

Dans notre société caractérisée par l'« individualisme démocratique », on assiste à un développement effréné de savoirs et de pratiques, qui menace le lien social. Le monde de la science n'y échappe pas : construction de disciplines hyperspécialisées, revendiquant un territoire et une reconnaissance toujours plus difficiles à obtenir.L'anthropologie clinique, en particulier d'inspiration phénoménologique, se veut - au plus près de son étymologie - une pensée sur la pratique des soins auprès de l'homme en souffrance. Sa visée : d'une part, réinscrire une clinique des fonctions de l'organisme dans une clinique du sujet humain incarné dans son monde quotidien et, d'autre part, proposer une méthode (la réduction phénoménologique) dans le but de dégager la vision de l'homme toujours très partielle que véhicule tout modèle scientifique.L'anthropologie clinique peut-elle ainsi contribuer à l'échange entre praticiens habitant des mondes séparés ?