Parent-offspring regression suggests heritable susceptibility to ectoparasites in a natural population of kittiwake Rissa tridactyla

Little information is available on the genetic variability of host susceptibility to parasites in natural populations despite its importance for the understanding of the evolution of host-parasite interactions. A long-term demographic and epidemiologic survey of a seabird population allowed us to investigate the potential correlation between parent and offspring ectoparasite load, while controlling for various environmental factors. In particular, parasite loads were measured for all individuals (i.e., parents and offspring) when they were nestlings and the effect of the year and breeding cliff were taken into account. The positive correlation found between parent and offspring parasite loads suggests a heritable susceptibility to ectoparasitism by ticks in this host population and that this character has the potential to respond to natural selection.