Genome resource banks pay conservation dividends

In the feature article, Howard et al. (2016) demonstrate the efficacy of a conservation strategy that has long been touted as an extinction fail-safe, genome resource banking (Holt & Pickard, 1999). While multiple research groups have demonstrated that genome resources can be successfully stored (reviewed in Fickel, Wagener & Ludwig, 2007) and used to produce animals (Comizzoli & Wildt, 2012), Howard et al. (2016) show for the first time that genome resources have the potential to increase the viability of a highly endangered, captive-bred population. Using banked semen from genetically valuable black-footed ferrets, they were able to increase gene diversity and decrease individual inbreeding in the captive population. This infusion of genetic diversity in the gene pool was achieved by artificially inseminating 18 females with semen from 16 ancestral males that had been cryopreserved between 10 and 20 years prior to the artificial insemination. Over the 4 years of the project, 18 females produced five pregnancies and eight kits. Those genetically valuable kits were then bred back into the captive breeding population. The genetic contribution of the ancestral males increased gene diversity because animals produced earlier in the population timeline had not undergone the extent of genetic erosion via drift that animals produced later had experienced. The net gain to gene diversity was modest. Although statistically significant, the authors report a <0.2% increase in population-wide gene diversity over the 4 years of the study. Is this statistical significance biologically significant? Likely not, as the authors reported that fecundity continued to decline in the captive population. A biologically significant increase in genetic diversity would constitute a genetic rescue, whereby fitness in the form of survival or reproduction in the population is also increased (Ingvarsson, 2001). No fitness gains are reported here and thus the authors correctly refrain from inferring a genetic rescue. This conclusion, however, should not diminish the accomplishments of this paper. Documenting a population-wide decline in genetic erosion is the next step in a proof of concept showing the utility of genome resource banks for genetic rescue, and thus this feature article represents a substantial contribution to conservation science and management. As the authors state themselves, integrating reproductive science into conservation practice is hard work and success comes incrementally. The take home message of this feature article is that transdisciplinary science promotes conservation. The black-footed ferret recovery program exemplifies this approach by integrating scientific disciplines with wildlife management. The research effort in this paper demonstrates the utility of inclusiveness: from the inception of the recovery program, reproductive scientists worked with field biologists, zoo curators, geneticists, immunologists and the federal caretakers of this species, the US Fish and Wildlife Service, to ensure that this species could be propagated in captivity and reintroduced back into the wild. The cross-talk among scientists of different disciplines was crucial to the process and one of the outputs of this innovation was the collection of genome resources at the beginning of the recovery process. As a result, semen from genetically valuable animals was cataloged and curated for 20 years, until technologies and science had been developed to utilize those resources. Those initial genome resource collection efforts have the potential to continue to pay conservation dividends. Other genetic resources collected at the time, fibroblasts, were taken from two black-footed ferrets not currently represented in the extant population. If these genetic resources were incorporated into the gene pool, it would increase the founding population size of extant black-footed ferrets from seven to nine individuals. The authors are appropriately cautious about heralding the potential success of this approach as it requires the adaptation of an unproven technique into conservation breeding, interspecies somatic cell transfer (Wisely et al., 2015). Caution but not dismissal is paramount to advancing reproductive science for the conservation community. The feature article illustrates that transferring biomedical technology into applied conservation science has potential risks and rewards. The process of this science is and should be slow and methodical, but