Document Type

Thesis

Degree

Master of Science

Major

Biology, Ecology

Date of Defense

11-18-2011

Graduate Advisor

Patricia Parker, PhD

Committee

Zuleyma Tang-Martinez, Ph.D.

Robert Marquis Ph.D.

Abstract

Introduced diseases such as avian malaria can severely impact the health of small populations and have been the cause of species extinctions. Island species are thought to be more highly susceptible to introduced diseases. These populations have likely evolved in the absence of various pathogens making them immunologically naïve to diseases that occur regularly in mainland species. The Galapagos archipelago still preserves 95% of its species diversity known to have occurred there. The introduction of Haemosporidian parasites in the genus Plasmodium, which cause avian malaria, have had detrimental impacts on naïve populations in other island systems. Until recently, avian malarial parasites had not been detected in the Galapagos avifauna; however, the presence of Plasmodium parasites has been documented in the endangered Galapagos penguin (Spheniscus mendiculus). Because avian malaria (Plasmodium relictum) causes high mortality in other avian species after initial exposure, there is concern for the conservation of the endemic Galapagos penguin. Using a Plasmodium spp. circumsporozoite protein antigen, we have standardized an enzyme-linked immunosorbent assay (ELISA) to test the level of exposure to the parasite in this species, as indicated by seroprevalence. Low seroprevalence would be consistent with high mortality, whereas high seroprevalence may indicate low Plasmodium-induced mortality under normal conditions. Serum from Galapagos penguins collected between 2004 and 2009 on the Galapagos archipelago was tested for the presence of anti - Plasmodium spp. antibodies. Penguins were also tested for prevalence of avian malaria parasites, determined by polymerase chain reaction (PCR). Total seroprevalence of malarial antibodies in this sample group was 97.2%, while total prevalence of Plasmodium parasites by PCR screening was 9.2%. This large discrepancy suggests high exposure to the parasite and low Plasmodium - induced mortality, at least under normal environmental conditions. The results of this study also suggest that parasite prevalence may be under-detected through PCR screening and multiple detection methods are necessary to better understand the extent of Plasmodium on the archipelago. It is extremely important to understand the distribution of this parasite on the islands and control any invasive threats before irreversible damage is done.

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