Poor but prosperous: how island biota survive genetic impoverishment.

Although often genetically impoverished due to founder effects, inbreeding, genetic drift and sequential bottlenecks, island populations tend to reach high densities and manage to adapt to the local environment. This is paradoxical because low allelic diversity can lead to inbreeding depression (reduction in fitness due to deleterious recessive alleles), and, on a longer timescale, to reduced genetic adaptability of populations. How and why do island populations, despite low genetic diversity, survive, adapt, and thrive? A first possibility might be that low heterozygosity does not translate into inbreeding depression, thanks to the mitigating effects of behavioural adaptations related to mate choice; or through the purging of deleterious variants. Alternatively, the fitness consequences of inbreeding may be bearable under the mild selection regimes typical for islands. However, evidence that either of these mechanisms is at work in wild populations remains scarce. In this project, I will study the "island paradox" in insular and mainland populations of the Italian wall lizard, Podarcis siculus. For the first time, the relationships between heterozygosity, physiological performance, behaviour, selection gradients and genomic structure are integratively used to unravel how insular populations overcome genetic impoverishment.

Keywords:ISLAND POPULATIONS, PERFORMANCE, EVOLUTION, INBREEDING

Disciplines:Animal ecology, Behavioural biology, Vertebrate biology, Biology of adaptation, Population, ecological and evolutionary genetics