. 1. A major, and largely unexplored, uncertainty in projecting the impact of climate change on biodiversity is the consequence of altered interspecific interactions, for example between parasitoids and their hosts. The present study investigated parasitism in the Brown Argus butterfly, Aricia agestis ; a species that has expanded northward in Britain during the last 30 years in association with climate warming.2. Aricia agestis larvae suffered lower mortality from parasitoids in newly colonised areas compared with long-established populations. This result was consistent over four consecutive generations (2 years) when comparing one population of each type, and also when several populations within the historical and recently colonised range of the species were compared within a single year. Thus, A. agestis appears to be partially escaping from parasitism as it expands northwards.3. Reduced parasitism occurred despite the fact that several of the parasitoid species associated with A. agestis were already present in the newly colonised areas, supported predominantly by an alternative host species, the Common Blue butterfly, Polyommatus icarus .4. As the species expand their distributions into areas of increased climatic suitability, invasion fronts may escape from natural enemies, enhancing rates of range expansion. The results suggest that the decoupling of interspecific interactions may allow some species to exploit a wider range of environments and to do so more rapidly than previously thought possible.Key words . Aricia agestis , butterfl y , climate change , enemy escape , parasitoids , range expansion . [413][414][415][416][417][418][419][420][421] have not been explored in relation to climate change, and the outcome could be quite different in this context. The biological invasions literature has largely considered species that have been transported long distances by humans, and that have left some or all of their natural enemies behind ( Clay, 2003;Mitchell & Power, 2003;Torchin et al. , 2003 ; Gröbler & Lewis, in press). Such invasive species will often be taxonomically or biologically distant from native species in the area under invasion, so natural enemies may not switch quickly to the invading host or prey. In contrast, natural enemies might be able to track species expanding their distributions in response to climate change much more effectively, given that the initial distribution change does not usually involve long-distance movement away from the long-standing geographic range, and that related species harbouring shared natural enemies may already occur in the regions of expansion.The present study tests the hypothesis that a species that has moved northwards as the climate has warmed has escaped from its natural enemies. Materials and methods The study systemThe study organisms were the Brown Argus butterfly [ Aricia agestis (Denis and Schiffermüller)] and its parasitoids. Aricia agestis has expanded its distribution northwards in Britain, moving at about 10 km per year since the early...

Many factors, including climate, resource availability, and habitat diversity, have been proposed as determinants of global diversity, but the links among them have rarely been studied. Using structural equation modeling (SEM), we investigated direct and indirect effects of climate variables, host-plant richness, and habitat diversity on butterfly species richness across Britain, at 20-km grid resolution. These factors were all important determinants of butterfly diversity, but their relative contributions differed between habitat generalists and specialists, and whether the effects were direct or indirect. Climate variables had strong effects on habitat generalists, whereas host-plant richness and habitat diversity contributed relatively more for habitat specialists. Considering total effects (direct and indirect together), climate variables had the strongest link to butterfly species richness for all groups of species. The results suggest that different mechanistic hypotheses to explain species richness may be more appropriate for habitat generalists and specialists, with generalists hypothesized to show direct physiological limitations and specialists additionally being constrained by trophic interactions (climate affecting host-plant richness).

The psychological, sociological and evolutionary roots of conspecific violence in humans are still debated, despite attracting the attention of intellectuals for over two millennia. Here we propose a conceptual approach towards understanding these roots based on the assumption that aggression in mammals, including humans, has a significant phylogenetic component. By compiling sources of mortality from a comprehensive sample of mammals, we assessed the percentage of deaths due to conspecifics and, using phylogenetic comparative tools, predicted this value for humans. The proportion of human deaths phylogenetically predicted to be caused by interpersonal violence stood at 2%. This value was similar to the one phylogenetically inferred for the evolutionary ancestor of primates and apes, indicating that a certain level of lethal violence arises owing to our position within the phylogeny of mammals. It was also similar to the percentage seen in prehistoric bands and tribes, indicating that we were as lethally violent then as common mammalian evolutionary history would predict. However, the level of lethal violence has changed through human history and can be associated with changes in the socio-political organization of human populations. Our study provides a detailed phylogenetic and historical context against which to compare levels of lethal violence observed throughout our history.

Aim Mountain regions are particularly well‐suited for investigating the impact of climate change on species ranges because they encompass both upper and lower limits of species distribution. Here, we investigate changes in the elevational distribution of dung beetle species (Coleoptera: Scarabaeoidea) in two separate mountain regions in Europe. Location South‐western Alps (France) and Sierra Nevada (Spain). Methods We compared historical and current data on dung beetle distributions along elevation gradients for 30 species in the SW Alps and 19 species in the Sierra Nevada. We tested for significant changes between survey periods in three parameters: mean elevation and upper and lower range limits. Results We found up‐slope range shifts for 63% and 90% of the species in the SW Alps and Sierra Nevada, respectively. Up‐slope range shifts resulted mainly from expansion of upper range limits in the SW Alps and from changes of both range limits in the Sierra Nevada. The magnitudes of range shifts were consistent with the level of warming experienced in each region, but they also reflected the asymmetrical warming observed along the elevation gradients. Smaller changes were observed for species reaching their historical range limits at the higher elevations, associated with a non‐significant increase in temperature between periods. Main conclusions The differences observed between regions are related to the geographical position of each mountain range, which determines the characteristics (including thermal tolerance) of the regional species pool, and the level of warming, which determines whether maximum thermal tolerance has been exceeded for the majority of species in the region. Our results highlight the importance of considering both the biogeography of the mountain and the species pool under study when assessing the sensitivity of species to future climate change in mountain regions.

No abstract