Conserving the Tansy Beetle: How can endangered species persist in dynamic habitat networks?

Conserving endangered species requires an understanding of their population dynamics in space and time. Many rare species function as metapopulations, where networks of populations exchange individuals through dispersal, allowing colonisation of empty patches and potentially rescuing populations from local extinction. However, turnover in the habitat patch network complicates these dynamics, as the

species tracks a moving target of available habitat. Better understanding of how species persist in dynamic habitat networks is needed to better assess regional extinction risk, species recovery after disturbance and target ecological restoration. This PhD will develop better understanding of the metapopulation dynamics of tansy beetles (Chrysolina

graminis) in patch networks formed by their host plant (tansy), in order to inform conservation management. The beetle has a stronghold on the banks of the River Ouse around York, representing most of its UK distribution. Because of its geographical restriction and vulnerability to disturbance (e.g.

major flooding), the tansy beetle is listed as Endangered in the National Red List for England and is prioritised for conservation as a Section 41 species in England. It has the support of the Species Recovery Trust (SRT, project CASE partner) and a dedicated conservation partnership in the Tansy Beetle Action Group (TBAG), who are both supporting this project.

The student will analyse an unprecedented >13-year survey dataset mapping beetles in thousands of tansy patches over 45 km of riverbank around York. The objectives are to: 1. Identify factors determining beetle colonisation and local extinction rates. This may include factors such as distance from other populations, flooding and grazing pressure.

2. Quantify dynamism in the tansy patch network and the factors de termining patch appearance and loss. This will inform efforts to maintain large and well connected networks of tansy plants. In addition, fieldwork will be used to better understand patterns identified in the analyses above. This includes:

1. Performing a field experiment on beetle colonisation of potted tansy plants, to determine the effect of matrix vegetation on dispersal, and establish whether tansy plants established away from the river are reached by dispersing beetles. 2. Field surveys of predation rates in tansy beetle eggs and larvae, which may be key to local population

persistence or extinction. Factors influencing predation may include predator abundance (e.g. ants or spiders), the plant species that eggs are laid on and grazing or mowing of the surrounding vegetation.