Risk maps summarizing landscape suitability of novel areas for invading species can be valuable tools for preventing species' invasions or controlling their spread, but methods employed for development of such maps remain variable and unstandardized. We discuss several considerations in development of such models, including types of distributional information that should be used, the nature of explanatory variables that should be incorporated, and caveats regarding model testing and evaluation. We highlight that, in the case of invasive species, such distributional predictions should aim to derive the best hypothesis of the potential distribution of the species by using (1) all distributional information available, including information from both the native range and other invaded regions; (2) predictors linked as directly as is feasible to the physiological requirements of the species; and (3) modelling procedures that carefully avoid overfitting to the training data. Finally, model testing and evaluation should focus on well-predicted presences, and less on efficient prediction of absences; a k-fold regional cross-validation test is discussed.

Recent global warming threatens many species and has already caused population-and species-level extinctions. In particular, high risks of extinction are expected for isolated populations of species with low dispersal abilities. These predictions rely on widely used 'climatic envelope' models, while individual responses, the ultimate driver of a species response to climate change, have been most often neglected. Here, we report on some changes in life-history traits of a dispersal-limited reptile species (a poorly studied taxa) living in isolated populations. Using long-term data on common lizards collected in southern France, we show that individual body size dramatically increased in all the four populations studied over the past 18 years. This increase in body size in all age classes appeared related to a concomitant increase in temperature experienced during the first month of life (August). Daily maximum temperature in August increased by 2.2 1C and yearling snout-vent-length increased by about 28%. As a result, adult female body size increased markedly, and, as fecundity is strongly dependent on female body size, clutch size and total reproductive output also increased. For one population where capturerecapture data were available, adult survival was positively related to May temperature. All fitness components investigated therefore responded positively to the increase in temperature, such that it might be concluded that the common lizard has been advantaged by the shift in temperature. We contrast these short-term results with the long-term habitat-based prediction that these populations located close to mountain tops on the southern margin of the species range should be unable to cope with the alteration of their habitat. To achieve a better prediction of a species persistence, one will probably need to combine both habitat and individual-based approaches.

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Aim  A debate exists as to whether present‐day diversity gradients are governed by current environmental conditions or by changes in environmental conditions through time. Recent studies have shown that latitudinal richness gradients might be partially caused by incomplete post‐glacial recolonization of high‐latitude regions; this leads to the prediction that less mobile taxa should have steeper gradients than more mobile taxa. The aim of this study is to test this prediction. Location  Europe. Methods  We first assessed whether spatial turnover in species composition is a good surrogate for dispersal ability by measuring the proportion of wingless species in 19 European beetle clades and relating this value to spatial turnover (βsim) of the clade. We then linearly regressed βsim values of 21 taxa against the slope of their respective diversity gradients. Results  A strong relationship exists between the proportion of wingless species and βsim, and βsim was found to be a good predictor of latitudinal richness gradients. Main conclusions  Results are consistent with the prediction that poor dispersers have steeper richness gradients than good dispersers, supporting the view that current beetle diversity gradients in Europe are affected by post‐glacial dispersal lags.

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BackgroundGenetic, phenotypic and ecological divergence within a lineage is the result of past and ongoing evolutionary processes, which lead ultimately to diversification and speciation. Integrative analyses allow linking diversification to geological, climatic, and ecological events, and thus disentangling the relative importance of different evolutionary drivers in generating and maintaining current species richness.ResultsHere, we use phylogenetic, phenotypic, geographic, and environmental data to investigate diversification in the Spanish sand racer (Psammodromus hispanicus). Phylogenetic, molecular clock dating, and phenotypic analyses show that P. hispanicus consists of three lineages. One lineage from Western Spain diverged 8.3 (2.9-14.7) Mya from the ancestor of Psammodromus hispanicus edwardsianus and P. hispanicus hispanicus Central lineage. The latter diverged 4.8 (1.5-8.7) Mya. Molecular clock dating, together with population genetic analyses, indicate that the three lineages experienced northward range expansions from southern Iberian refugia during Pleistocene glacial periods. Ecological niche modelling shows that suitable habitat of the Western lineage and P. h. edwardsianus overlap over vast areas, but that a barrier may hinder dispersal and genetic mixing of populations of both lineages. P. h. hispanicus Central lineage inhabits an ecological niche that overlaps marginally with the other two lineages.ConclusionsOur results provide evidence for divergence in allopatry and niche conservatism between the Western lineage and the ancestor of P. h. edwardsianus and P. h. hispanicus Central lineage, whereas they suggest that niche divergence is involved in the origin of the latter two lineages. Both processes were temporally separated and may be responsible for the here documented genetic and phenotypic diversity of P. hispanicus. The temporal pattern is in line with those proposed for other animal lineages. It suggests that geographic isolation and vicariance played an important role in the early diversification of the group, and that lineage diversification was further amplified through ecological divergence.

Summary1. Biological invasions represent a major threat to human health, ecosystem functioning and global biodiversity. Insect pests affecting agriculture and forestry are of special importance. Estimations of climatic similarity between a species' native range and potential zones of invasion can be useful for preventing new invasions, spreads and ulterior contacts among populations from multiple invasions. 2. We estimated areas climatically favourable for the establishment of the western corn rootworm (WCR), an insect pest of maize Zea mays in North America that has recently invaded Central Europe through multiple invasions, and it has the potential of invasion mainly in the Northern Hemisphere. 3. We used complementary techniques to assess the biological relevance of predictors and obtain areas of climatic favourability. The biological relevance of variables was first assessed accounting for two main components of the WCR's environmental niche (marginality and specialisation). Then, the most relevant predictors were used to obtain either climatic envelopes or environmental distances regarding the WCR's native range. Model outputs and predictor relevance were independently assessed in the currently invaded region of Europe and through the spatial projection of proposed physiological thresholds from previous empirical studies. Lastly, as examples of application for given time periods, we fed back results of environmental distances with maize data for a 10-year period in Europe, and refined global risk maps with the main maize zones for the year 2000. 4. We present global zones of climatic favourability and invasion risk for the WCR, with emphasis on the Northern Hemisphere. The northern and north-west range limits predicted by the climatic envelope in the WCR's native range mirrored the independently characterised physiological limits. Also, our model outputs explained some of the patterns observed in Europe supporting the validity of our procedures. 5. Synthesis and applications. Assessments of climatic favourability for the western corn rootworm can provide information on areas of invasion risk. Our study highlights the combination of holistic and reductionist approaches as a useful protocol to evaluate models and ⁄ or infer causality. Our methodology can be an efficient tool in combating future potential invasions, spreads and secondary contact zones of insect pests by reducing uncertainty regarding where to allocate prevention and ⁄ or eradication efforts.

Aim Climatic factors are known to influence species distributions. However, elucidating the underlying mechanisms is challenging because direct and indirect effects of climatic and non-climatic factors are correlated. In the absence of this covariation and at fine-grain resolutions the direct effect of climate via physiological constraints should be stronger on the distributions of ectothermic organisms. So far, no comprehensive study has explicitly tested the influence of climate on species distributions by quantitatively comparing ectothermic and endothermic vertebrates. Location Peninsular Spain.Methods Presence-absence data of native terrestrial vertebrates in Peninsular Spain were modelled using generalized additive models to disentangle the influence of climate and other contemporary correlated factors (topography and plant cover). We performed partial regressions to partition the deviance explained by climatic and non-climatic effects into independent and shared components. We compared the independent contributions of climatic and non-climatic effects between ectothermic and endothermic vertebrates, and among mammals, birds, reptiles and amphibians. ResultsAfter reducing the covariation with non-climatic factors, climate explained a greater proportion of deviance in ectotherms than in endotherms. Also, the contribution of temperature was highest for reptiles, and the contribution of precipitation was highest for amphibians, after extracting their overlaps with precipitation and temperature, respectively. The contribution of topography and plant cover remained high for birds after extracting the overlap with climate. Main conclusionsOur results are consistent with the prediction that, at fine resolutions, the direct influence of climate (via physiological constraints) on range distributions is stronger in ectothermic vertebrates. Also, at least for birds, indirect effects of climate (via plant productivity) and other habitat characteristics remained relatively important once their covariation with climate was reduced. This study shows that controlling the direct effects of climate by their indirect effects and/or other correlated factors, combined with comparisons among functional groups, can be a useful approach to elucidate causal links with the spatial patterns of organisms.