Ex situ collections and their potential for the restoration of extinct plants

The alarming current and predicted species extinction rates have galvanized conservationists in their efforts to avoid future biodiversity losses but for species extinct in the wild, few options exist. We posed the question, can these be restored, and if so, what role can ex situ plant collections (i.e. botanic gardens, germplasm banks and herbaria) play in the recovery of plant genetic diversity? We reviewed the relevant literature to assess the feasibility of recovering lost plant genetic diversity using ex situ material and the chances of survival of subsequent translocations. Thirteen attempts of recovering species extinct in the wild were found, most of which from material preserved in botanic gardens (12) and seed banks (2). A single case of a locally extirpated population was recovered from herbarium material. Eight (60%) of these cases were successful or partially successful translocations of the focal species or population, while the other five failed or was too early to judge. Our review exposes the many constraints of using ex situ source material for the restoration of plant genetic diversity to the wild, but also highlight the opportunities that modern collecting practices present for plant conservation. Limiting factors are the scarcity of available source material stored ex situ, low viability and reduced longevity of the material, low genetic variation, lack of evolution (especially for material stored in germplasm banks and herbaria) and socio-economic constraints. However, our review suggests that all types of ex situ collections may effectively contribute to plant species conservation, if their use is informed by a thorough understanding of the aforementioned issues. For these reasons, we conclude that the recovery of plant species currently classed as extinct in the wild is not 100% successful and the possibility to achieve this should not be used as a justification for insufficient in situ conservation efforts. This article is protected by copyright. All rights reserved.