A comparison of genetic diversity between the Galapagos Penguin and the Magellanic Penguin

The Galapagos Penguin (Spheniscus mendiculus) is a United States federally listed endangered species with populations on the Galapagos Islands of Fernandina and Isabela. Although the waters around the islands are normally productive, low productivity during El Nino years results in high adult penguin mortality and low recruitment in following years. We used microsatellite markers developed. for Spheniscus penguins to study the long term genetic effects of serial bottleneck events in the Galapagos Penguin, and compared this variation to that of its congener, the Magellanic penguin (Spheniscus magellanicus). The observed heterozygosity for the Galapagos Penguin was 3%, significantly lower than the 46% heterozygosity of the Magellanic Penguin. This low level of heterozygosity is directly related to its low effective population size. While this population has survived long term, presumably without high levels of genetic variation, we feel that the greater frequency of El Nino events, coupled with increased human impacts such as introduced disease, oil discharge, and competition with fisheries, may put the species in particular danger of extinction.