A paper, written by University of Michigan researcher Johannes Foufopoulos, an assistant professor at the School of Natural Resources and Environment who specializes in disease ecology, and collaborators from Princeton University and the University of Upsalla, investigates the relationship between immunological investment (how developed is the body's immune system), native parasite abundance, and island size. The findings were published online June 8 in the Proceedings of the Royal Society of London.
The paper helps scientists understand how island populations respond to invasive parasite species. The introduction of exotic parasites and diseases through travel, commerce and domestic animals and the resulting destruction in native wildlife populations is a worldwide problem, Foufopoulos said, but it's even more serious for species that have evolved on islands.
For example, in the Hawaiian islands, many native bird species have gone extinct after the introduction of avian malaria, he said. The Galapagos authorities are now realizing that the greatest danger to the islands' wildlife comes from exotic species, such as invasive pathogens, accidentally introduced by humans.
The study shows that people on islands have different immune systems "and this may be the explanation for their susceptibility to invasive diseases," Foufopoulos said.
The team found that larger islands with larger bird populations harbor more native parasites and diseases, because the number of parasites is directly dependent on the size of the population. Island size and parasite richness then influenced the strength of the immune response of the hosts.