Genetic rescue or outbreeding depression? How to manage endangered populations.

The project aims to investigate whether genetic rescue, translocations of individuals between different populations lead to improved genetic health and larger local populations of the green toad, Bufotes viridis, and the natterjack toad (Epidalea viridis) or whether there are genetic problems, outbreeding depression, in connection with the ongoing Swedish action programs for the species.

The project is a collaboration between university researchers and biologists linked to the county administration boards that are in charge of the action programs.

We intend to use genome sequencing methods and experiments with larvae of different origins to investigate population structure, possible gene flow, degree of inbreeding, disease state, and local adaptations in various local populations of and in a breeding population held in captivity at the zoo Nordens Ark (a so-called ex-situ population).

This population is used for re-introductions e.g. on Öland.Our results will be used to improve and guide the work with the action program while examining fundamental questions in conservation biology research: When and how should genetic rescue be initiated? How genetically similar should the stocks be to achieve the desired effect and to avoid breeding depression?

How outbred should the ex-situ stock be? These are issues where the scientific community is divided and where more empirical knowledge is needed.