Natasha LeBas, Jennifer Rodger, Rowan Lymberry, Joseph Tomkins, Dominque Blache

As a response to the current biodiversity crisis, active management of threatened species has become more frequent (Hoffmann et al., 2010), with predator free havens an increasingly common conservation management strategy (Legge et al., 2022). In Australia, where introduced predators such as cats (Moseby et al., 2015) and foxes (Radford et al., 2018) are one of the largest threats to native fauna, havens have played a key role in maintaining viable populations of endemic mammals (Legge et al., 2018). Concerns, however, have been increasingly raised that populations in predator free havens, or similarly those that are captive bred or on islands, rapidly lose antipredator traits (Beauchamp, 2004; Blumstein & Daniel, 2005; Harrison, Phillips, et al., 2023; Jolly & Phillips, 2021; Jolly et al., 2018; Smith & Blumstein, 2008). Here we suggest that some of the selective pressures and mechanisms that may explain the rapid loss of these traits may have been overlooked. There is convincing evidence within the animal production literature that a fearful, high anxiety temperament (typically associated with anti-predator behaviours) is genetically linked to reduced fecundity; a relationship that may explain the rapid loss of fearful antipredator traits as a byproduct of selection for increased fecundity. We also propose a mechanism by which antipredator behaviour could be maintained in populations that are expected to evolve predator naivety.