Authors

J Clark¹; J S Garbutt¹; L McNally¹; T Little¹;  ¹ University of Edinburgh

Discussion

Extrinsic mortality will determine population age structure, which in turn will influence disease spread when individuals of different ages differ in susceptibility, or when maternal age determines offspring susceptibility. Our experiments show that Daphnia magna offspring born to young mothers are more susceptible to the specialized parasite Pasteuria ramosa, than those born to older mothers. Previous observations show that susceptibility declines with age in this system. We used a Susceptible-Infected compartmental model to investigate how age specific susceptibility and maternal age effects on offspring susceptibility interact with demographic factors to affect disease spread. Our results show a scenario where an increase in extrinsic mortality drives an increase in transmission potential and so we identify a realistic context, in which age effects and maternal effects produce conditions favouring disease transmission. Ongoing experiments are investigating genotypic variation in age effects on parasite fitness.