Climate and habitat configuration limit range expansion and patterns of dispersal in a non-native lizard

Abstract

Aim Invasive species are one of the main causes of biodiversity loss worldwide. As introduced populations increase in abundance and geographical range, so does the potential for negative impacts on native communities. As such, there is a need to better understand the processes driving range expansion as species become established in recipient landscapes. We investigated the potential for population growth and range expansion of introduced populations of a non-native lizard (Podarcis muralis), considering multi-scale factors influencing growth and spatial spread. Location England, UK Methods We collated records of P. muralis presence through field surveys and a citizen science campaign. We used presence-only models to predict climate suitability at a national scale (5km resolution), and fine-scale habitat suitability at the local scale (2m resolution). We then integrated local models into an individual-based modelling platform to simulate population dynamics and forecast range expansion for 10 populations in heterogeneous landscapes. Results National-scale models indicated climate suitability restricted to the southern parts of the UK, limited by a latitudinal cline in overwintering conditions. Patterns of population growth and range expansion were related to differences in local landscape configuration and heterogeneity. Growth curves suggest populations could be in the early stages of exponential growth. However, annual rates of range expansion are predicted to be low (5-16 m). Conclusions We conclude that extensive nationwide range expansion through secondary introduction is likely to be restricted by currently unsuitable climate beyond southern regions of the UK. However, exponential growth of local populations in habitats providing transport pathways is likely to increase opportunities for regional expansion. The broad habitat niche of P. muralis, coupled with configuration of habitat patches in the landscape, allows populations to increase locally with minimal dispersal.