Population genetic structure of two water strider species in the Ecuadorian Amazon

1. We used mtDNA sequence variation to estimate population genetic structure between and among water strider populations of Potamobates williamsi and P . sumaco in the Ecuadorian Amazon.
2. Sequencing of the COI mitochondrial gene revealed 16 haplotypes, which were summarised into four haplotype groups. P . williamsi and P . sumaco shared two common and widespread haplotypes.
3. Population structure was moderate and gene flow was low. Both air and river distances were significantly correlated with gene flow and, thus, indicative of isolation by distance.
4. The genetic structure within and among populations of P. williamsi and P. sumaco was probably not influenced by the dynamic tropical lotic system.     

Enigmatic tubes associated with microbial crusts from the Late Jurassic of the Northern Calcareous Alps (Austria): a mutualistic sponge–epibiont consortium?

Irregular tube-shaped microfossils incertae sedis are a typical constituent of Late Jurassic shallow-water reefal carbonates of the Northern Calcareous Alps of Austria and are described in open nomenclature. The enigmatic, polymorphous spar-filled tubes with neither observable external nor internal skeletal elements occur either free within peloidal sediments or mostly fixed to skeletal substrates embedded in microbial crusts including the genera Labes Eliášová, Crescentiella Senowbari-Daryan et al . or Isnella Senowbari-Daryan. The tubes are varied in shape and closely resemble different taxa of sponges. As the microbial crusts preferentially occur associated with these tubiform microfossils, this association is suggested to be non-parasitic and mutualistic. Without the surrounding crusts, the existence of these animals would have been masked or perhaps even totally lost in the fossil record expressing the importance of these findings as a characteristic element in the inventory of Late Jurassic reefal biocoenoses.     

Tracking genes of ecological relevance using a genome scan in two independent regional population samples of Arabis alpina

Understanding the genetic basis of adaptation in response to environmental variation is fundamental as adaptation plays a key role in the extension of ecological niches to marginal habitats and in ecological speciation. Based on the assumption that some genomic markers are correlated to environmental variables, we aimed to detect loci of ecological relevance in the alpine plant Arabis alpina L. sampled in two regions, the French (99 locations) and the Swiss (109 locations) Alps. We used an unusually large genome scan [825 amplified fragment length polymorphism loci (AFLPs)] and four environmental variables related to temperature, precipitation and topography. We detected linkage disequilibrium among only 3.5% of the considered AFLP loci. A population structure analysis identified no admixture in the study regions, and the French and Swiss Alps were differentiated and therefore could be considered as two independent regions. We applied generalized estimating equations (GEE) to detect ecologically relevant loci separately in the French and Swiss Alps. We identified 78 loci of ecological relevance (9%), which were mainly related to mean annual minimum temperature. Only four of these loci were common across the French and Swiss Alps. Finally, we discuss that the genomic characterization of these ecologically relevant loci, as identified in this study, opens up new perspectives for studying functional ecology in A. alpina, its relatives and other alpine plant species.