|Aim We explore the relationship between current European distributions of
amphibian and reptile species and observed climate, and project species potential
distributions into the future. Potential impacts of climate warming are assessed by
quantifying the magnitude and direction of modelled distributional shifts for
every species. In particular we ask, first, what proportion of amphibian and reptile
species are projected to lose and gain suitable climate space in the future?
Secondly, do species projections vary according to taxonomic, spatial or
environmental properties? And thirdly, what climate factors might be driving
projections of loss or gain in suitable environments for species?
Methods Distributions of species are modelled with four species–climate
envelope techniques (artificial neural networks, generalized linear models,
generalized additive models, and classification tree analyses) and distributions
are projected into the future using five climate-change scenarios for 2050. Future
projections are made considering two extreme assumptions: species have
unlimited dispersal ability and species have no dispersal ability. A novel hybrid
approach for combining ensembles of forecasts is then used to group linearly
covarying projections into clusters with reduced inter-model variability.
Results We show that a great proportion of amphibian and reptile species are
projected to expand distributions if dispersal is unlimited. This is because
warming in the cooler northern ranges of species creates new opportunities for
colonization. If species are unable to disperse, then most species are projected to
lose range. Loss of suitable climate space for species is projected to occur mainly
in the south-west of Europe, including the Iberian Peninsula, whilst species in the
south-east are projected to gain suitable climate. This is because dry conditions in
the south-west are projected to increase, approaching the levels found in North
Africa, where few amphibian species are able to persist.
Main conclusions The impact of increasing temperatures on amphibian and
reptile species may be less deleterious than previously postulated; indeed, climate
cooling would be more deleterious for the persistence of amphibian and reptile
species than warming. The ability of species to cope with climate warming may,
however, be offset by projected decreases in the availability of water. This should
be particularly true for amphibians. Limited dispersal ability may further increase
the vulnerability of amphibians and reptiles to changes in climate.|