Populations at the edge: range dynamics and conservation of the Great Crested Newt under global change.

Under anthropogenic exploitation and rapid environmental changes, many species are challenged with novel conditions, some are shifting their ranges moving to new suitable areas, and many are now threatened or extinct.
Populations at the edges of species' range are key and often the most vulnerable: they are small, fragmented and less connected; harbour low genetic diversity and occupy suboptimal habitat; often face multiple anthropogenic stressors such as habitat loss and deterioration. However, populations that are at the range leading margin (the edge towards the direction of climate change) are key for successful species' range shifting: they already occupy locations where suitability will improve and thus could potentially readily expand, and might possess unique and locally favourable genetic variants. Understanding how these populations will respond to environmental change, both ecologically and evolutionarily, whether they will be able to persist under multiple natural and anthropogenic stressors, and how better we can assist them in this process, is crucial for effective species' conservation under global change.
Predictive process-based models, that integrate the fundamental processes shaping species' ecology and adaptive responses, such as genetic variation, demography and dispersal, together with assessing impacts of multiple environmental stressors, are a powerful tool to both better understanding species' range dynamics and making better predictions of likely species' responses to future environmental change. These models are being developed, and they are now ripe for testing and for applications of conservation relevance.
Amphibians are declining globally and are a high priority for biodiversity conservation. They are particularly vulnerable to multiple stressors as they rely on wetlands, an ecosystem particularly challenged by climate change and habitat loss, and are threatened by invasive species, diseases and pollution. The great crested newt Triturus cristatus is a declining species in Europe. In Britain it is an important wetland flagship species and has shown the highest rate of decline in recent years amongst native amphibians. In Scotland, T. cristatus is uncommon, with a restricted and fragmented range and, importantly, Scotland represents the north-west range of the species' world range. Critically, the species has a disjoint distribution in Scotland with an 80 km gap between the most northerly site in Fife and the most southerly Highland site. Much suitable unoccupied habitat has been identified and more is predicted to become suitable with climate change, creating potential for these edge populations to expand their range. However, multiple threats such has increasing habitat fragmentation, due to urbanization, agricultural changes and industrial developments, increasing drought, reduced genetic diversity, and increasing risk of predation from non-native species such as the signal crayfish and American mink, make it extremely uncertain whether this expansion and persistence will be at all possible.
T. cristatus is thus an excellent and important species for investigating ecological and adaptive responses to environmental changes of populations at the warming range margins, and for applying new integrated process-based methods to predict these responses and guide conservation interventions.
The overall aim of this project is to understand and predict the persistence of T. cristatus in Scotland under ongoing climate change and multiple stressors, and its potential expansion from marginal populations, to inform conservation management, moving towards a pro-active, rather than reactive, management of declining amphibians under global change.