On the island of New Guinea, some extraordinary lizards have green blood, due to high levels of biliverdin, a bile pigment, which overwhelms the color of their red blood cells. In humans and other vertebrates, biliverdin (and bilirubin) are toxic waste products that cause jaundice and are associated with pathology in newborns and diseases such as Gilbert's and Crigler-Najjar syndromes. As the concentration of biliverdin in these lizards would cause jaundice and death in other animals, the adaptive significance of their high bile pigment levels is unknown. One hypothesis is that it is an anti-parasitic strategy. Lizards are hosts to malaria parasites but preliminary data collected by the PI's show a trend towards reduced levels of malaria infection in green-blooded lizards. The goals of this project are to conduct fieldwork at nine locales in Papua New Guinea and to use a large number of tissue and blood samples already in hand to obtain better estimates of the diversity and relationships of skinks and their malaria parasites, in order to more conclusively test this hypothesis. Thus, this project will make numerous novel contributions to systematics, biodiversity, and parasitology.
The broader impacts of this project will include development of middle/high school curriculum materials, training of undergraduate and graduate students, and various international partnerships. As no other animals have ever been found that can survive this level of biliverdin in their blood, the study may ultimately provide some clues to better understand jaundice and in doing so contribute to biomedicine and economic development.
