Using biotic interactions in broad-scale estimates of species’ distributions

International audienceAim: To examine the combined effect of abiotic and biotic factors on species distri-butions in a marine environment. Specifically, we aim to account for the effects of trophic interactions at broad scales in ecological niche models (ENMs) of sea kraits (Laticauda: Reptilia) by including the potential distribution of food resources as pre-dictor variables.Location: Oceania and Southeast Asia.Methods: First, we outline a simple method to generate biotic interaction variables for ENMs. We then test whether ENMs that include biotic interactions perform bet-ter than ENMs based on abiotic variables only.Results: The models based on biotic interactions (i.e. trophic interactions) and abi-otic variables slightly outperformed the models informed only by abiotic variables. We found a strong relationship between prey species richness and probability of distribution of predator (sea kraits). The models that included potential distributions of prey species as predictor variables showed an increase in proportion of pixels predicted present and a decrease in omission error, compared with models based only on abiotic variables.Main conclusions: Distribution estimates of predator species at broad scales are more accurate if calibration of ENMs includes relevant biotic variables (prey species richness, in this study). Hence, when data are available, biotic variables should be included in ENMs

Refining model estimates of potential species’ distribution to relevant accessible areas

International audienceDispersal is an important, yet overlooked phenomenon when studying species’ distributions using ecologicalniche models (ENMs). Here, we use species’ dispersal limits to evaluate and refine ENM estimates only to theareas accessible to the species within the study region and, thereby, enhance the model interpretations. First,we ran multiple ENMs to estimate the distribution of sea krait species in both marine and terrestrialenvironments. Second, we estimated dispersal of the sea kraits using a cost analysis approach. Finally, weoutline a new approach that combines dispersal models and ENMs with the purpose of estimating theaccessible range when projecting species’ distribution estimates outside the known species range. We foundthat only a small proportion of the area the ENMs were projected over was accessible to sea kraits. Themajority of the suitable areas for sea kraits are within the accessible area. Outside the accessible area, there isonly a very limited suitable area for sea kraits. Our results suggest that when dispersal is taken into account,sea kraits seem to occupy most of their suitable available niche and that they may be unable to colonize muchof the area outside of their dispersal ranges. Using dispersal estimates to refine species’ distribution pre-dictions is a useful tool for refining the area of focus when ENM results are interpreted. Estimating species’dispersal also helps evaluate the ability of the models to predict the species’ distributions in areas that are notaccessible to the species and, hence, the potential commission error represented by overpredictio

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Data from: Anthropogenic impact or anthropogenic accommodation? Distribution range expansion of the common wall lizard (Podarcis muralis) by means of artificial habitats in the north-eastern limits of its distribution range

During 2005-2008, field observations were made on the distribution and habitat occupation by Podarcis muralis in the middle Bistrita river basin. Prior to our study, this lizard was known from only 5 localities in Romanian Moldavia (Bicaz, Cheile Bicazului, Lacu Roşu, Gherman and Dodeni). Through the present paper the authors acknowledge the existence of 28 sites populated by P. muralis in Moldavia and propose a new model for the range expansion of the species in the area using man-made structures such as road and railway fences and road beds, benefiting from the mild climate provided by the Izvorul Muntelui barrier lake and forming insular populations to further colonize suitable habitats