Geographic variation in the immunoglobulin levels in pygoscelid penguins

Antarctic organisms, including penguins, are susceptible to parasites and pathogens. Effects of infestation could differ in different locations along a geographical gradient from north to south consistent with conditions that affect the prevalence and virulence of parasites and pathogens. The immune system, including immunoglobulins as the main component of the humoral immune response, is the major way by which organisms confront infestation. We investigated the variation in immunoglobulin levels in three species of antarctic penguins (Pygoscelis antarctica, Pygoscelis papua, and Pygoscelis adeliae) along a geographical gradient from King George Island (62°15′S) to Avian Island (67°46′S). We found that immunoglobulin levels increased northwards in all the three species. This could indicate a higher impact of parasites and/or pathogens relative to the existing gradient in temperatures along this coast. Changing temperatures, consistent with global climate change, could be altering the ecology of parasite or pathogen infestation within the biota of northern Antarctica. We have also found marginal differences in immunoglobulin levels between sexes in both chinstrap and gentoo penguins.