Natural regeneration of Fagus sylvatica L. adapts with maturation to warmer and drier microclimatic conditions

Population genetic studies are efficient for inferring the invasion history based on a
comparison of native and invasive populations, especially when conducted at species
scale. An expected outcome in invasive populations is variability loss, and this is especially
true in self-fertilizing species. We here focus on the self-fertilizing Pseudosuccinea
columella, an invasive hermaphroditic freshwater snail that has greatly expanded
its geographic distribution and that acts as intermediate host of Fasciola hepatica, the
causative agent of human and veterinary fasciolosis. We evaluated the distribution of
genetic diversity at the largest geographic scale analysed to date in this species by surveying
80 populations collected during 16 years from 14 countries, using eight nuclear
microsatellites and two mitochondrial genes. As expected, populations from North
America, the putative origin area, were strongly structured by selfing and history and
harboured much more genetic variability than invasive populations. We found high
selfing rates (when it was possible to infer it), none-to-low genetic variability and
strong population structure in most invasive populations. Strikingly, we found a
unique genotype/haplotype in populations from eight invaded regions sampled allover the world. Moreover, snail populations resistant to infection by the parasite are
genetically distinct from susceptible populations. Our results are compatible with
repeated introductions in South America and ﬂash worldwide invasion by this unique
genotype/haplotype. Our study illustrates the population genetic consequences of bio-
logical invasion in a highly selﬁng species at very large geographic scale. We discuss
how such a large-scale ﬂash invasion may affect the spread of fasciolosis

Self‐fertilization, long‐distance flash invasion and biogeography shape the population structure of Pseudosuccinea columella at the worldwide scale

Unravelling the riddle of Radix: DNA barcoding for species identification of freshwater snail intermediate hosts of zoonotic digeneans and estimating their inter-population evolutionary relationships.

Despite schistosomiasis is one of the most prevalent tropical diseases in developing countries and and large flows of migrants come from countries where the disease is endemic, imported urinary schistosomiasis is still not easily recognized in non-endemic areas, especially if not subjected to specific investigations. Moreover schistosomiasis is currently not reportable in any European public health system. The data presented in this report were collected were collected between asylum seekers by a simple screening method based on a prior or actual history of a macroscopic hematauria. In case of a history of gross hematuria, the patient underwent to specific exams standardized for the diagnosis of urinary schistosomiasis. Our data show that the prevalence of the disease has been largely underestimated by European Surveillance Systems; in fact in a small population of young asylum seekers coming from endemic areas for schistosomiasis, we found a significant number of individuals with symptomatic disease. Given that the disease typically has an insidious course, it is highly probable that a screening procedure is able to identify early asymptomatic or mildly symptomatic subjects and avoid the serious complications that are present in advanced stages of disease. Given the limits and the costs of a late diagnosis and that an effective treatment is available, subjects from endemic areas should be actively screened for urinary schistosomiasis.

L. Nkengazong

Papers

Strong genetic structure in Cameroonian populations of Bulinus truncatus (Gastropoda: Planorbidae), intermediate host of Schistosoma haematobium.