Clumped distributions of herbivorous insect eggs often result from independent assessments of individual plants by different ovipositing females. Here we ask whether, in addition, plants might be rendered more or less attractive to ovipositing Melitaea cinxia butterflies by presence of conspecific eggs and/or by prior larval attack. Both eggs and larval damage rendered Veronica spicata plants significantly more acceptable; the effect of eggs was particularly strong. Larval damage caused a marginally significant increase in acceptability of Plantago lanceolata, but there was no trend for an effect of eggs on this host. Variable oviposition preferences of Melitaeine butterflies are known to drive their metapopulation dynamics by affecting rates of emigration and patch colonization. Therefore variable host acceptability, as documented here, should do likewise, reducing emigration rates at high population densities where V. spicata is present in the landscape and complementing Allee effects that are already known in this system.

The western world has witnessed a rising epidemic of chronic inflammatory disorders, such as allergies and asthma. This epidemic is expected to spread also to the rest of the world, where allergies have to date been practically absent, along with adoption of western lifestyle. In parallel, biological diversity is globally declining. This inspired Ilkka Hanski, together with medical doctors, to formulate the biodiversity hypothesis of allergic disease. This hypothesis proposes that reduced contact with natural environments, including natural microbial diversity, is associated with unhealthy human microbiota, less able to educate the immune system. Contact with beneficial bacteria, particularly early in life, seems to be instrumental to the normal development of immune responses. Changes in lifestyle and diet, destruction of natural environments, and urbanisation threaten our natural exposure to these beneficial bacteria and thus also reduce their impact on our physiology. To ensure a healthy life, we need to preserve biodiversity in the environment and make sure it finds a favourable home in us. In this review, we will focus on the role of commensal microbiota in human health and wellbeing, as well as the interaction between our microbiota and environmental microbiota, highlighting the contribution of Ilkka Hanski.

Extinction—recolonization dynamics is known to promote “fugitive coexistence” in patchy environments: a species that is an inferior competitor but a better colonizer may persist by exploiting the period between its colonization of a patch and the arrival of a superior competitor. Here I use a simple model to demonstrate the plausibility of a different type of fugitive coexistence. I show that, under some circumstances, a “jack of all trades” plastic species can persist despite competition from an adaptable species that has the genetic potential to adapt locally and outcompete the plastic species in every patch. This persistence can be mediated by two forces that impede local adaptation: gene flow and extinction—recolonization dynamics. In the latter case, the persistence of the plastic species is of a fugitive nature; however, it is not mediated by an earlier colonization. Rather, it relies on the fact that, following recolonization, the adaptable species is often locally maladapted. This opens a time window for the plastic species to multiple and produce propagules before the other species becomes locally adapted, and thus competitively superior.

Grazing by large mammals can affect small-mammal populations by modifying the ground-layer vegetation, which provides them with food and shelter. The aim of this study was to investigate the impact of semi-domesticated reindeer grazing on smallmammal abundance in boreal forests/subarctic tundra ecosystems in a large-scale exclosure experiment in northernmost Finnish Lapland. In our experiment spanning four years, reindeer grazing affected the abundance of arvicoline voles, which were less abundant in grazed areas. This was probably due to a reduction in the abundance and height of bilberry, an important forage plant for both voles and reindeer. Changes in ground-layer vegetation affected the general condition of bank voles, which had significantly lower body mass in grazed areas. The abundance of insectivorous shrews was also reduced by grazing, probably due to a reduction in ground-dwelling invertebrates as an indirect effect of changes in the composition of ground-layer vegetation. A grazing-induced red...

The latitudinal diversity gradient predicts higher species richness at lower latitudes. Here, we utilize the data from a long-term monitoring with malaise traps to analyse if spider communities in Sweden are affected by geographic gradients and if these effects hold independent of forest type. The species richness and the effective number of species in spider communities were not significantly related to the latitudinal gradient. The effective number of species and the taxonomic distinctness of spider communities were related to longitude, with a higher number, but fewer related species in western parts of Sweden. The species and family composition were significantly related to latitude independent of forest type, with a dominance of Linyphiidae individuals and species in the north. Our study demonstrates the suitability of malaise trap sampling to contribute to a better understanding of local spider communities, as several rare and locally new species were recorded in this study.

There is a lack of documentation on the consumption of toxic fruits by carnivores. To quantify the importance of toxic fruits in the diets of badgers (Meles meles), foxes (Vulpes vulpes) and martens (Martes sp.), we collected faeces of these animals along nine transects (total 30.4 km long, 2 m wide) during the fruiting seasons (June–November) in 2010 and 2011. From 619 faecal samples we found seeds of 16 fleshy-fruited plant species, including four species with toxic fruits. Surprisingly, the fruit of Convallaria majalis having a high content of toxic substances was also eaten by these animals. Fruits of C. majalis were found in faeces in late summer/autumn after early frost when maturing processes had reduced the content of toxic substances in the mesocarp. Toxic fruits were detected in 6.3% of all faeces sampled (n = 619). The proportion of toxic fruits in the diet was the highest (up to 10.5%) in martens as compared with that in badgers and foxes (2.2% and 0.7%, respectively).

In Norway, recovering populations of large carnivores commonly prey on roe deer (Capreolus capreolus). Understanding predator habitat use and ecology requires fine-scaled information on prey distribution and abundance. However, the massive spatial scales at which large carnivores use the landscape presents many practical and statistical challenges for developing functional prey distribution models. Pellet-count data from > 1000 km of transects gathered across southeastern Norway between 2005 and 2011 were used to derive a map of the relative prey abundance for roe deer. These data were modeled using zero-inflated hurdle models using both environmental and anthropogenic variables. Snow depth and agricultural fields were the most significant variables in explaining both presence and abundance. Internal k-cross validation of the model showed medium accuracy (Spearman's r = 0.35), whereas external evaluation carried out on the basis of independently collected snow-tracking data (Spearman's r = 0.37) and hunti...

The ringed seal (Phoca hispida) is dependent on sufficient ice and snow cover for a breeding habitat. Therefore, climate change has a negative effect on pup survival. We developed methods to estimate perinatal mortality and to mitigate the effects of mild winters on the critically endangered subspecies (P. h. saimensis). Underwater surveys were used for collecting pup carcasses and placentas. Lanugo pup mortality was 13.5% and Brucella sp. was not found in the placentas. Camera traps showed sporadic human and medium-sized carnivore activity in the breeding habitat. Although carnivore activity was most intensive at lair sites, no penetration of the lairs was observed. We developed a method to mitigate the effects of poor snow cover by piling up snowdrifts (n = 117) at potential lair sites. Seals subsequently occupied 62% of these snow drifts. We suggest that the methods developed in this study should be implemented to conserve the Saimaa ringed seal.

Indicator species have been proposed to be used for revealing common status of ecosystems and their biodiversity. We studied breeding forest birds in southern Finland. Our aim was to find bird species combinations that would predict species richness of forest bird assemblages at several spatial scales. We evaluated statistical models that included 1–5 indicator candidate species, and ranked them according to the Bayesian information criterion. The red-breasted flycatcher Ficedula parva, the pygmy owl Glaucidium passerinum and the three-toed woodpecker Picoides tridactylus were found to be the best multiscale indicators. Models at smaller spatial scales, including several indicator species better explained the total variation in species richness. The indicators mostly revealed properties of the forest site rather than variation in species richness caused by species interactions. Our results show that a suitable set of indicator species may be a useful and quick method for the evaluation of bird diversity in forest environments.

Assessing the origin of trait variation during evolutionary history is an important first step in understanding evolutionary diversification. Here, we tested the influence of shared ancestry and climate, and the interplay of both, on the variation of ten life history traits in Triturus newts. We showed that (1) climate alone has driven the evolution of variation in five life history traits, (2) phylogenetic signal partly explains the variation in two traits (vitellus diameter and snout—vent length of larvae at metamorphosis), and (3) the interplay of shared ancestry and climate explains the variation in one trait (snout—vent length of larvae at metamorphosis). This study highlights the coarse-grained influence of shared ancestry and climate on the structure of phenotypic trait variation in Triturus and provides a handle for more detailed, fine grained studies on the evolution of phenotypic trait variation.