Maximising evolutionary potential in functional proxies for extinct species: a conservation genetic perspective on de‐extinction

Abstract

Summary 1.De-extinction sensu stricto is the resurrection of phenotypic traits once possessed by extinct species to create extant functional proxies. To realise the ecological benefit of de-extinction, self-sustaining (genetically viable) populations of functional proxies are required. 2. It is often implied, yet rarely stated, that the genetic challenges associated with the survival and recovery of extant threatened species in an effort to conserve biodiversity are also relevant to the use of functional proxies of extinct species as a conversation tool. 3. Here, we highlight the importance of prioritising evolutionary potential À the capacity to evolve (adapt) in response to environmental change À in populations of functional proxies. 4. We use conservation genetic principles to describe impediments to the creation and maintenance of evolutionary potential as a series of potentially unavoidable genetic bottlenecks (preextinction, resurrection, captive, translocation). 5. To give any successfully translocated populations of functional proxies the best chance to survive beyond the first few generations in the wild, we advocate the use of a holistic framework that includes the creation of sufficiently large, genetically diverse populations that harbour the ability to adapt to a changing environment.

The ecology of de‐extinction

“…Iacona et al (2017) model de-extinction as a reversible link in what was once a one-way path from extant to extinct, and demonstrate that this can change how resources should be allocated to recovery efforts. It has been argued before that the release of a resurrected species is a reintroduction (Seddon, Moehrenschlager & Ewen 2014), and we see from Steeves, Johnson & Hale (2017) that the release of large numbers of suitable founders will be one requisite of restoration success. Intensive post-release monitoring will also be required to track outcomes, in terms of both focal species population establishment and growth, and the ecological consequences for other ecosystem components.…”

“…Extinction marks an irreversible break in the eco-evolutionary trajectory of a species (Robert et al 2017); there is a need to preserve the evolutionary potential of resurrected species by overcoming genetic bottlenecks at every stage of a project (Steeves, Johnson & Hale 2017); there is some uncertainty around whether a resurrected species might ever be restored to functionally meaningful densities (McCauley et al 2017), and our knowledge of past ecosystems will be incomplete for all but recent extinctions, making it difficult to predict the implications and impacts of attempts to restore the ecological interactions that have been lost with extinction (Wood, Perry & Wilmshurst 2017). But let's assume that we have been able successfully to resurrect through interspecies cloning, sufficient numbers of sufficiently genetically diverse individuals of a reasonable proxy of a species that went extinct relatively recently, and that its reintroduction has the potential to restore, within a largely intact and well-understood ecosystem, some ecological function lost through extinction.…”

Ancient DNA as a Tool for Navigating the Anthropocene

“…The ethics behind de-extinction is being vigorously debated at the general theoretical scale (Diehm 2015;Martinelli, Oksanen, and Siipi 2014;Minteer 2014;Oksanen 2008;Oksanen and Siipi 2014). Reflecting active research into the realization of de-extinction, there is also debate around the practicalities and methods of specific deextinction projects Desalle and Amato 2017;Peers et al 2016;Shapiro 2017;Steeves, Johnson, and Hale 2017).…”

De‐extinction and evolution

“…One peculiarity of de‐extinction with respect to initial genetic variation is that initial numbers of individuals and initial genetic variation can be completely decoupled in cases the operations are based on, for example multiple clones from a single source (see Steeves, Johnson & Hale ).…”

“…Numbers of released individuals in reintroduction programmes typically range from a few tens to a few hundred individuals, and empirical reintroduction surveys suggest that there is a positive relationship between the number of released individuals and programme success (Wolf et al 1996), yet the potential contribution of genetic effects to this pattern has not been clearly established. One peculiarity of de-extinction with respect to initial genetic variation is that initial numbers of individuals and initial genetic variation can be completely decoupled in cases the operations are based on, for example multiple clones from a single source (see Steeves, Johnson & Hale 2017).…”