The Potential for Genetic Rescue in the Endangered South Atlantic Island Floras

The world faces a sixth mass extinction, a crisis that will result in major losses of global biodiversity. Islands are at the coalface of this extinction crisis with higher extinction rates than continental areas, and increased threats from climate change. In small and fragmented populations of endangered species, genetic rescue has the potential to be a valuable tool for species conservation. Tools for the maintenance of genetic variation and hence the potential for adaptation to environmental change are critical for tackling the extinction crisis. We review the current literature on genetic rescue as a conservation tool in plants and assess the potential for genetic rescue in the highly endangered floras of the South Atlantic Islands. Several case studies of species likely to be good candidates for genetic rescue are highlighted. Genetic rescue is likely to result in a more comprehensive and informed conservation of the genetic variation in the endangered plants of the South Atlantic. This will be extremely useful when the potential for adaptation to environmental change needs to be maximized. Several knowledge gaps remain, a combined approach that measures both molecular and ecological traits in semi-controlled common garden trials is suggested and the role of ex situ institutions and botanic gardens is likely to be crucial to its success.