Investigating adaptation to captivity: a data-driven approach

Abstract

Captive breeding programs are an increasingly common tool to prevent extinction and provide a source population for reintroductions to the wild. Breeding programs attempt to ‘halt evolution’ in captivity, however, there will always be differences between captive and wild environments. Genetic adaptation to captivity as a result of artificial or unintended selection is therefore likely. In this thesis, I examined (1) whether there are differences in reproductive success in captive environments between wild-born and captive-born animals, (2) long-term multi-generational changes in reproductive success in captivity and (3) how changes may occur between generations of captive breeding, including through variation in reproductive success and undetected selection. As the consequences of adaptation to captivity are of relevance to all captive breeding programs, I used a data-driven approach to examine the response of multiple species to captive breeding. In captivity, wild-born animals across diverse taxa had higher reproductive success than their captive-born counterparts and fitness changes occurred over multiple generations of captive breeding. The Tasmanian devil was then used as a case study to allow a closer examination of genetic change in captivity. High variation in the reproductive success of Tasmanian devils housed in free-range enclosures may reduce genetic diversity and accelerate adaptation to captivity if unmanaged, however mate choice did not explain the reproductive skew. Undetected early viability selection, where offspring deviate from Mendelian inheritance, was identified as a mechanism for undetected genetic change to occur in captive breeding programs. This thesis provides new information about the consequences and possible mechanisms of adaptation to captivity. Useful recommendations are provided to conservation managers considering the impact of adaptation to captivity in their species.