Brockington Group: The mathematics of the metacollection: optimal allocation of plant diversity across the world's ex-situ collections
Supervisor
Professor Sam Brockington
Importance of Research
No single botanic garden or seed bank can conserve plant diversity alone. Collectively, however, the world's seed banks and botanic gardens function as a distributed metacollection. But recent analysis of 2.2 million accession records shows that this system has reached carrying capacity: total accessions and species diversity have both plateaued, while wildsourced acquisition and international exchange have declined sharply. If the system cannot grow, the only remaining lever is how existing capacity is allocated. At present, allocation is emergent rather than designed, and duplication of easy taxa coexists with total absence of threatened ones. There is no theory that tells us how many sites should hold a species, which sites and with how many individuals each.
Project Summary
This project will develop the mathematics of the metacollection: a formal optimisation theory for distributing plant diversity across a network of institutions under finite capacity. Drawing on systematic conservation planning, metapopulation theory and portfolio optimisation, you will formulate collection allocation as a constrained optimisation problem in which the objective combines species and genetic representation, expected persistence and equity, and the constraints capture space, climate suitability, horticultural expertise and access legislation. Because gardens experience partially independent risks, redundancy has quantifiable value, and the optimal number of holding institutions per taxon can be derived rather than assumed.
What the successful applicant will do
You will build simulation models of the global metacollection, parameterised with real accession, survival and institutional data. You will implement and compare optimisation algorithms, including complementarity-based greedy heuristics, integer programming and stochastic dynamic programming, and analyse the sensitivity of solutions to uncertainty and to equity constraints. You will deliver both theory and a usable prioritisation tool, tested with partner gardens, and will engage directly with the international policy conversation on Global Biodiversity Framework targets.