Effect of species range shifts on trophic networks in freshwater ecosystems

As climates warm in the 21st century, many species are shifting their geographic distributions towards higher latitudes and elevations. Previous studies have indicated that range shifting species may express greater metabolic and behavioural flexibility than species which have not recently undergone biogeographic shifts, with long-term implications for the structure and function of high latitude communities. For instance, research has already revealed that range shifting species often negatively impact species richness and biodiversity of areas where they become established. However, the processes by which community turnover occurs in colonised sites are little known, rendering future biodiversity predictions difficult.
We propose to investigate how range-shifting species affect patterns of community composition, using pond damselflies (Odonata: Zygoptera: Coenagrionidae) as a model system. These species are rapidly range shifting in Britain under climate change, and are important, keystone predators in freshwater communities; the Irish species also have high conservation value. Our previous work has indicated that range shifts in Coenagrionid damselflies are associated with species turnover in high latitude freshwater ecosystems, but the effects on trophic interactions and resulting community resilience to future environmental change remain largely unknown.

To examine the ecosystem consequences of range shifts, the student will:
1) Relate the colonisation dynamics of range-shifting damselflies in Scotland and Ireland to changes in freshwater trophic network structure, accounting for land use and climatic variability across the study region, using hierarchical regression models.
2) Investigate differences in phenotypes, behaviour and metabolic rates under different thermal regimes in range-shifting vs. non-range shifting damselflies across the region, in order to identify alternative mechanisms mediating biotic interactions in range-shifting vs. non-range shifting populations.
3) Using data derived from Next Generation Sequencing approaches, identify genetic variants in range-shifting vs. non-range shifting damselfly species that are associated with particular trophic networks (Obj 1) and traits (Obj 2).

The project will contribute to our understanding of how communities are likely to respond to ongoing range shifts, and identify the mechanisms underpinning global homogenisation of biodiversity. The results also have the potential to make fundamental contributions to the development of the rapidly advancing field of functional community ecology.

The student will be based primarily at the University of Aberdeen, under the supervision of Dr Lesley Lancaster, who is a leading researcher in understanding evolutionary and community consequences of range shifts. The student will be co-supervised by Dr Paul Caplat at Queen’s University Belfast, who develops novel approaches to predict community patterns at multiple scales from life-history traits, climate and land use. Dr Sarah Helyar (Queen’s University) will supervise the genetic part of the work. There is potential for the student to establish links with NGOs responsible for freshwater restoration in Scotland and Ireland for application of the results. The student will form part of the QUADRAT doctoral training programme, which provides internationally cutting edge training in environmental management leadership.