Delineating fine-scale genetic units in amphibians: probing the primacy of ponds

The population structure of pond-breeding amphibians is shaped by their distinct breeding foci, but it is unclear to what extent this is reflected in the fine-scale distribution of genetic diversity. We used microsatellite genotypes to investigate the genetic signatures of 24 populations of European newts, Triturus cristatus and T. marmoratus, inhabiting 21 ponds in a confined study area (7.5 · 3.5 km) in western France. Employing a Bayesian clustering approach based on individual genotypes that minimises departures from Hardy–Weinberg equilibrium and linkage disequilibrium, no evidence was found for within-pond substructuring. Subjecting all sampled ponds simultaneously to this procedure revealed a clear signal of partitioning, with the most likely number of clusters however below the actual number of ponds (seven in T. cristatus, three in T. marmoratus). A more hierarchical Bayesian approach, with pond as analysis unit, was achieved to separate ponds from genetically more meaningful units, and reduced the T. cristatus populations to 11 clusters, and the T. marmoratus populations to five clusters. We were unable to specify a minimum nearest-neighbour distance where ponds are separate units, probably due to both historical and current demographic processes. The implications for strategies to manage and conserve endangered amphibians in human-altered landscapes are discussed

Co-learning in a Digital Community : Information Literacy and Views on Learning in Pre-school Teacher Education

Through analysing how different views on learning enable pre-school teacher students to distinguish and use affordances offered by digital tools and the learning environment, this paper seeks to connect modes of appropriation, identity positions and information activities to types of information literacy. Identity, particularly views on learning, is analysed to find out how a Facebook group to some students remains a sustainable digital community throughout teacher education. The paper reports results from a netnographical study conducted between 2012 and 2015. The material used in the analysis consists primarily of 12 semi-structured student interviews and 6 teacher interviews. In the thematic analysis, a socio-cultural perspective on identity is applied. The concept affordance is used to analyse how identity is connected to use of digital tools and the learning environment. The findings show how the appropriation of the Facebook group is connected to identity positions and views on learning in two types of information literacy: a relational information literacy and a pragmatic information literacy. The normative function of co-learning is found to be an important aspect of the learning environment of pre-school teacher education that explains why the digital community can be experienced as either including or excluding

Hybridisation among groupers (genus Cephalopholis) at the eastern Indian Ocean suture zone: taxonomic and evolutionary implications

Hybridisation is a significant evolutionary process that until recently was considered rare in the marine environment. A suture zone in the eastern Indian Ocean is home to numerous hybridising sister species, providing an ideal opportunity to determine how hybridisation affects speciation and biodiversity in coral reef fishes. At this location, hybridisation between two grouper (Epinephelidae) species: Cephalopholis urodeta (Pacific Ocean) and C. nigripinnis (Indian Ocean) was investigated to determine the genetic basis of hybridisation and to compare the ecology and life history of hybrids and their parent species. This approach aimed to provide insights into the taxonomic and evolutionary consequences of hybridisation. Despite clear phenotypic differences, multiple molecular markers revealed hybrids, and their parent species were genetically homogenous within and (thousands of kilometres) outside of the hybrid zone. Hybrids were at least as fit as their parent species (in terms of growth, reproduction, and abundance) and were observed in a broad range of intermediate phenotypes. The two species appear to be interbreeding at Christmas Island due to inherent biological and ecological compatibilities, and the lack of genetic structure may be explained by three potential scenarios: (1) hybridisation and introgression; (2) discordance between morphology and genetics; and (3) incomplete lineage sorting. Further molecular analyses are necessary to discriminate these scenarios. Regardless of which applies, C. urodeta and C. nigripinnis are unlikely to evolve in reproductive isolation as they cohabit where they are common (Christmas Island) and will source congeneric mates where they are rare (Cocos Keeling Islands). Our results add to the growing body of evidence that hybridisation among coral reef fishes is a dynamic evolutionary factor. © 2016 Springer-Verlag Berlin Heidelberg

Evolution of adaptive diversity and genetic connectivity in Arctic charr (Salvelinus alpinus) in Iceland

The ecological theory of adaptive radiation predicts that the evolution of phenotypic diversity within species is generated by divergent natural selection arising from different environments and competition between species. Genetic connectivity among populations is likely also to have an important role in both the origin and maintenance of adaptive genetic diversity. Our goal was to evaluate the potential roles of genetic connectivity and natural selection in the maintenance of adaptive phenotypic differences among morphs of Arctic charr, Salvelinus alpinus, in Iceland. At a large spatial scale, we tested the predictive power of geographic structure and phenotypic variation for patterns of neutral genetic variation among populations throughout Iceland. At a smaller scale, we evaluated the genetic differentiation between two morphs in Lake Thingvallavatn relative to historically explicit, coalescent-based null models of the evolutionary history of these lineages. At the large spatial scale, populations are highly differentiated, but weakly structured, both geographically and with respect to patterns of phenotypic variation. At the intralacustrine scale, we observe modest genetic differentiation between two morphs, but this level of differentiation is nonetheless consistent with strong reproductive isolation throughout the Holocene. Rather than a result of the homogenizing effect of gene flow in a system at migration-drift equilibrium, the modest level of genetic differentiation could equally be a result of slow neutral divergence by drift in large populations. We conclude that contemporary and recent patterns of restricted gene flow have been highly conducive to the evolution and maintenance of adaptive genetic variation in Icelandic Arctic charr