Phylogeny and androgenesis in the invasive Corbicula clams (Bivalvia, Corbiculidae) in Western Europe

info:eu-repo/semantics/publishe

Étude comparative de la densité et du déplacement des Desmans des Pyrénées Galemys pyrenaicus (É. Geoffroy Saint-Hilaire, 1811) par une méthode non invasive

peer reviewe

Against all odds: trehalose-6-phosphate synthase and trehalase genes in the bdelloid rotifer Adineta vaga were acquired by horizontal gene transfer and are upregulated during desiccation.

The disaccharide sugar trehalose is essential for desiccation resistance in most metazoans that survive dryness; however, neither trehalose nor the enzymes involved in its metabolism have ever been detected in bdelloid rotifers despite their extreme resistance to desiccation. Here we screened the genome of the bdelloid rotifer Adineta vaga for genes involved in trehalose metabolism. We discovered a total of four putative trehalose-6-phosphate synthase (TPS) and seven putative trehalase (TRE) gene copies in the genome of this ameiotic organism; however, no trehalose-6-phosphate phosphatase (TPP) gene or domain was detected. The four TPS copies of A. vaga appear more closely related to plant and fungi proteins, as well as to some protists, whereas the seven TRE copies fall in bacterial clades. Therefore, A. vaga likely acquired its trehalose biosynthesis and hydrolysis genes by horizontal gene transfers. Nearly all residues important for substrate binding in the predicted TPS domains are highly conserved, supporting the hypothesis that several copies of the genes might be functional. Besides, RNAseq library screening showed that trehalase genes were highly expressed compared to TPS genes, explaining probably why trehalose had not been detected in previous studies of bdelloids. A strong overexpression of their TPS genes was observed when bdelloids enter desiccation, suggesting a possible signaling role of trehalose-6-phosphate or trehalose in this process.info:eu-repo/semantics/publishe

A Microbial Tale of Farming, Invasion and Conservation: On the Gut Bacteria of European and American Mink in Western Europe

peer reviewedAbstract One of the threats that the critically endangered European mink (Mustela lutreola) faces throughout its relict range, including the occidental population, is the impact of the American mink (Mustela vison) invasion in its natural habitat. We aimed to explore the differences in microbiota and genetic diversity between European and American mink to test phylosymbiosis theory. We investigated the gut microbiota composition of European and American mink in a controlled environment (captive breeding compounds and fur farms respectively) to account for the impact of the environment on gut bacterial composition. We compared them to the gut microbiota of both mink species in the natural environment across multiple habitats. Our exploratory results showed differences between free-ranging and captive individuals, with more extreme changes in American mink compared to European mink. However, feral American mink from a long-established population exhibited gut bacterial composition closer to the free-ranging native species compared to more recently established feral populations. This result could be explained by dietary shifts in the area sampled based on prey availability through different landscape, but also to a lesser extent due to greater genetic differentiation. This exploratory work contributes to the scarce literature currently available on the dynamics between gut microbiota and mammal invasion

Genetic structure of fragmented southern populations of African Cape buffalo (Syncerus caffer caffer)

peer reviewedBackground African wildlife experienced a reduction in population size and geographical distribution over the last millennium, particularly since the 19th century as a result of human demographic expansion, wildlife overexploitation, habitat degradation and cattle-borne diseases. In many areas, ungulate populations are now largely confined within a network of loosely connected protected areas. These metapopulations face gene flow restriction and run the risk of genetic diversity erosion. In this context, we assessed the “genetic health” of free ranging southern African Cape buffalo populations (S.c. caffer) and investigated the origins of their current genetic structure. The analyses were based on 264 samples from 6 southern African countries that were genotyped for 14 autosomal and 3 Y-chromosomal microsatellites. Results The analyses differentiated three significant genetic clusters, hereafter referred to as Northern (N), Central (C) and Southern (S) clusters. The results suggest that splitting of the N and C clusters occurred around 6000 to 8400 years ago. Both N and C clusters displayed high genetic diversity (mean allelic richness (Ar) of 7.217, average genetic diversity over loci of 0.594, mean private alleles (Pa) of 11), low differentiation, and an absence of an inbreeding depression signal (mean FIS = 0.037). The third (S) cluster, a tiny population enclosed within a small isolated protected area, likely originated from a more recent isolation and experienced genetic drift (FIS = 0.062, mean Ar = 6.160, Pa = 2). This study also highlighted the impact of translocations between clusters on the genetic structure of several African buffalo populations. Lower differentiation estimates were observed between C and N sampling localities that experienced translocation over the last century. Conclusions We showed that the current genetic structure of southern African Cape buffalo populations results from both ancient and recent processes. The splitting time of N and C clusters suggests that the current pattern results from human-induced factors and/or from the aridification process that occurred during the Holocene period. The more recent S cluster genetic drift probably results of processes that occurred over the last centuries (habitat fragmentation, diseases). Management practices of African buffalo populations should consider the micro-evolutionary changes highlighted in the present study