Genetic rescue restores long-term viability of an isolated population of adders (Vipera berus)

Climate change is regarded as a major threat to global biodiversity [1]. However, another key driver of declines in biodiversity during the last century has been, and still is, the devastating impact of anthropogenic habitat destruction [2]. Human degradation of natural habitats has resulted in large, formerly homogeneous areas becoming exceedingly isolated and fragmented, resulting in reduced genetic diversity and a concomitant increased vulnerability to pathogens [3] and increased risk of inbreeding [4]. In order to restore genetic diversity in small isolated or fragmented populations, genetic rescue - that is, an intervention in which unrelated individuals are brought into a population, leading to introduction of novel alleles - has been shown to reduce the deleterious effects of inbreeding [4,5].