Conservation in a dynamic landscape: metapopulation ecology of the endangered tansy beetle
Conserving endangered species requires an understanding of their population dynamics in space and time. Many rare species function as metapopulations, in which networks of populations exchange individuals through dispersal, allowing colonisation of empty patches and potentially rescuing populations from local extinction. Turnover in the patch network itself complicates these dynamics, as the species tracks a moving target of habitat patches. Ultimately, better understanding of metapopulation dynamics in dynamic networks will allow better assessment of regional extinction risk, species recovery after disturbance and better targeting of ecological restoration efforts.
This studentship focuses on the tansy beetle (Chrysolina graminis). The beetle has a stronghold (meta)population on the banks of the River Ouse around York, which was thought to be its entire UK population. However, it was recently rediscovered in two East Anglian fenland sites where it had been thought extinct. Because of its geographical restriction and vulnerability (e.g. to major flooding), the tansy beetle is listed as Endangered in the National Red List for England, prioritised for conservation as a Section 41 species in England and was a UK Biodiversity Action Plan species. 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).
The first focus of the studentship will be on beetle metapopulation dynamics in a dynamic network of host plant (tansy) patches around York. Building on our previous work on patch occupancy and dispersal and an unprecedented >12-year SRT and TBAG survey dataset mapping thousands of tansy patches over 45 km of riverbank, the student will investigate:
1. How dynamic is the tansy patch network? What determines patch appearance and loss?
2. How does the beetle metapopulation function? What determines colonisation and local extinction?
3. What are the long-term risks of regional extinction and how might this be minimised?
A second focus will be on better understanding the re-discovered fenland populations to inform conservation. The student will investigate:
1. How are beetle distributions structured in the fenland sites? Are they aggregated in particular areas or on particular host plants?
2. How does performance vary on alternative host plants? The fenland populations seem to use the mint family rather than tansy but the effects of host plant choice are not known.
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By Geoff Oxford – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=13290111