Data from: Exposing the structure of an Arctic food web

How food webs are structured has major implications for their stability and dynamics. While poorly studied to date, arctic food webs are commonly assumed to be simple in structure, with few links per species. If this is the case, then different parts of the web may be weakly connected to each other, with populations and species united by only a low number of links. We provide the first highly resolved description of trophic link structure for a large part of a high-arctic food web. For this purpose, we apply a combination of recent techniques to describing the links between three predator guilds (insectivorous birds, spiders, and lepidopteran parasitoids) and their two dominant prey orders (Diptera and Lepidoptera). The resultant web shows a dense link structure and no compartmentalization or modularity across the three predator guilds. Thus, both individual predators and predator guilds tap heavily into the prey community of each other, offering versatile scope for indirect interactions across different parts of the web. The current description of a first but single arctic web may serve as a benchmark toward which to gauge future webs resolved by similar techniques. Targeting an unusual breadth of predator guilds, and relying on techniques with a high resolution, it suggests that species in this web are closely connected. Thus, our findings call for similar explorations of link structure across multiple guilds in both arctic and other webs. From an applied perspective, our description of an arctic web suggests new avenues for understanding how arctic food webs are built and function and of how they respond to current climate change. It suggests that to comprehend the community-level consequences of rapid arctic warming, we should turn from analyses of populations, population pairs, and isolated predator–prey interactions to considering the full set of interacting species. The data package contains eleven datasets

Data from: Candidate genes for colour and vision exhibit signals of selection across the pied flycatcher (Ficedula hypoleuca) breeding range

The role of natural selection in shaping adaptive trait differentiation in natural populations has long been recognized. Determining its molecular basis, however, remains a challenge. Here, we search for signals of selection in candidate genes for colour and its perception in a passerine bird. Pied flycatcher plumage varies geographically in both its structural and pigment-based properties. Both characteristics appear to be shaped by selection. A single-locus outlier test revealed two of fourteen loci to exhibit significantly elevated signals of divergence. The first of these, the follistatin gene, is expressed in the developing feather bud and found in pathways with genes that determine the structure of feathers and may thus be important in generating variation in structural colouration. The second is a gene potentially underlying the ability to detect this variation: SWS1 opsin. These two loci were most differentiated in two Spanish pied flycatcher populations, which are also among the populations that have the highest ultraviolet reflectance. The follistatin and SWS1 opsin genes, thus provide strong candidates for future investigations on the molecular basis of adaptively significant traits and their co-evolution. The data package contains two datasets: - The SNP genotypes of the pied flycatcher individuals utilised in this study by population. Data have been collected in the field and the genotypes subsequently generated in a genetics laboratory. The loci are listed at the start of the page, in the order that they presented in in the file (left to right).The alleles are in 2-digit format, one column per locus. Z-linked loci are denoted with a Z and haplotypes denoted with the abbreviaiton 'hap'. Population names correspond to the sampling site of the individual (e.g. Jeseniky = Jeseniky Mountains, the Czech Republic) as presented in Table 1 of the publication. - The microsatellite genotypes for the pied flycatchers collected from Dartmoor, which have not previously been published elsewhere. Data have been collected in the field and the genotypes subsequently generated in a genetics laboratory. The alleles are in 2-digit format, one column per locus. The loci are listed at the start of the page, in the order that they presented in in the file (left to right). The microsatellite data for the other populations is the same as that presented in Lehtonen et al. 2009 Molecular Ecology 18:4463-447