Population genomics of the critically endangered Aeolian wall lizard (Podarcis raffonei)

Small populations tend to have a higher extinction risk and this can be explained by a loss of genetic diversity and an accumulation of harmful mutations (genetic load). Here we compared the genetic load between two exceptionally small populations of the Aeolian wall lizard (La Canna and Strombolicchio) and the Sicilian wall lizard. The population of La Canna is characterized by extremely low effective population size and unique levels of inbreeding, qualifying as a wild inbred strain, but we demonstrate that the genetic load is similar to the one of Strombolicchio. This suggests the existence of a maximum level of tolerable genetic load, but not a minimum level of genetic variation, for a small population to persist.