Adaptive radiation is the evolution of ecological and phenotypical diversity. It arises via ecological opportunity that promotes the exploration of underutilized or novel niches mediating specialization and reproductive isolation. The assumed precondition for rapid local adaptation is diversifying natural selection, but random genetic drift could also be a major driver of this process. We used 27 populations of European whitefish (Coregonus lavaretus) from nine lakes distributed in three neighbouring subarctic watercourses in northern Fennoscandia as...

The composition of local mammalian carnivore communities has far-reaching effects on terrestrial ecosystems worldwide. To better understand how carnivore communities are structured, we analyzed camera trap data for 108,087 trap days across 12 countries spanning 5 continents. We estimate local probabilities of co-occurrence among 768 species pairs from the order Carnivora and evaluate how shared ecological traits correlated with probabilities of co-occurrence. Within individual study areas, species pairs co-occurred more frequently than expected at random....

While there are extensive macro- and microfossil records of a range of plants and animals from Quaternary records, earthworms and their close relatives among annelids are not preserved as fossils, and therefore we have limited knowledge of their Quaternary distributions. This lack of fossils means that clitellate worms (Annelida) are currently underused in palaeoecological research, even though they can provide valuable information about terrestrial and aquatic environmental conditions. Their DNA might be preserved in sediments,...

1. Comparative studies about the relationships between vital rates and ecological traits at the community level are conspicuously lacking for most taxa because estimating vital rates requires detailed demographic data. Identifying relationships between vital rates and ecological traits could help to better understand ecological and evolutionary demographic mechanisms that lead to interspecific differences in vital rates. 2. We use novel dynamic N-mixture models for counts to achieve this for a whole avian community comprising 53...

1. The boreal biome exhibits distinct alternative ecosystem states with high and low levels of tree-cover. Insect outbreaks facilitated by climate warming could potentially drive transitions from high to low tree-cover states. We investigated whether two key premises for such outbreak-induced transitions – critical thresholds (tipping points) and positive feedbacks that could maintain alternative states – are present in the northern-boreal mountain birch forest of Fennoscandia. Here, climate warming has promoted range expansions of defoliating...

Whether the ovarian fluid represents a selective environment influencing cryptic female choice was tested using an external fertilizer experiencing intense sperm competition and large effects of ovarian fluid on sperm swimming behaviour - the Arctic charr (Salvelinus alpinus). We physically separated the ovarian fluid from the eggs of reproductively active females and reintroduced either their own ovarian fluid or fluid from another female to the eggs. The eggs were then fertilized in vitro in a...

Chemical hazard assessment requires extrapolation of information from model organisms to all species of concern. The Sequence Alignment to Predict Across Species Susceptibility (SeqAPASS) tool was developed as a rapid, cost effective method to aid cross-species extrapolation of susceptibility to chemicals acting on specific protein targets through evaluation of protein structural similarities and differences. The greatest resolution for extrapolation of chemical susceptibility across species involves comparisons of individual amino acid residues at key positions involved...

Ecological models have been criticized for a lack of validation of their temporal transferability. Here we answer this call by investigating the temporal transferability of a dynamic state-space model developed to estimate season-dependent biotic and climatic predictors of spatial variability in outbreak abundance of the Norwegian lemming. Modelled summer and winter dynamics parametrized by spatial trapping data from one cyclic outbreak were validated with data from a subsequent outbreak. There was a distinct difference in...

Metabarcoding of lake sediments have been shown to reveal current and past biodiversity, but little is known about the degree to which taxa growing in the vegetation are represented in environmental DNA (eDNA) records. We analysed composition of lake and catchment vegetation and vascular plant eDNA at 11 lakes in northern Norway. Out of 489 records of taxa growing within 2 m from the lake shore, 17-49% (mean 31%) of the identifiable taxa recorded were...

Variability in biotic interaction strength is an integral part of food web functioning. However, the consequences of the spatial and temporal variability of biotic interactions are poorly known, in particular for predicting species abundance and distribution. The amplitude of rodent population cycles (i.e. peak phase abundances) has been hypothesized to be determined by vegetation properties in tundra ecosystems. We assessed the spatial and temporal predictability of food and shelter plants effects on peak phase small...

A mismatch between male and female gamete release in external fertilizers can result in reduced or failed fertilization, sperm competition and reduced paternity. Here, spawning behaviour of free-living Arctic charr (Salvelinus alpinus) was video recorded, and their reproductive behaviour was analysed. From evaluating 157 spawning events we observed that females mainly spawned with a guarding male and the female and the guarding male synchronized timing of gamete releaseunder sperm competition. Although sneakers spawned with higher...

Large-scale patterns in species diversity and community composition are associated with environmental gradients, but the implications of these patterns for food-web structure are still unclear. Here, we investigated how spatial patterns in food-web structure are associated with environmental gradients in the Barents Sea, a highly productive shelf sea of the Arctic Ocean. We compared food webs from 25 subregions in the Barents Sea and examined spatial correlations among food-web metrics, and between metrics and spatial...