Biology ETDs


Spencer Galen

Publication Date



The tropical Andes of South America represent a highly complex landscape characterized by physical barriers to dispersal and stark ecological gradients. The study of intraspecific genetic diversity in widespread Andean species has the potential to elucidate the historical biogeographic events that have driven diversification as well as the processes by which organisms have adapted to their environments in this region. The house wren (Troglodytes aedon) provides a convenient system for the study diversification and adaptation in the Andes, as it is distributed widely across both biogeographic barriers and heterogeneous environments. In chapter one, I utilize house wren and malaria parasite mtDNA to investigate host-parasite phylogeography and diversification. I also examine the bioclimatic correlates of malaria abundance in order to understand how the host and external environment interact to shape malaria biogeography. I found that the house wren and its Haemoproteus parasites co-diversified during the Pleistocene within the Andes, but that the diversification of the parasites was diffuse with respect to the regional avifauna. House wren-specific Haemoproteus parasites were polyphyletic and appeared to have speciated by switching hosts from other South American bird species. Malaria distributions were structured with respect to climate, with parasites in the genus Leucocytozoon significantly associated with high elevation habitats above 2,000 m. In chapter two I use a population genetic approach to study the evolution of hemoglobin in response to high altitude hypoxia in Andean house wrens. I discovered five amino acid substitutions in the genes that encode the subunits of the major hemoglobin isoform that segregated with respect to elevation. One substitution, β(55)Val==>Ile, was significantly structured between low (<1,000 m) and high (>3,000 m) elevation house wren populations. The genetic structure associated with β(55) was supported by coalescent analyses that revealed reduced migration at the βA locus. These findings suggest that the β(55)Ile allele confers increased hemoglobin-O2 affinity and is adaptive at high altitudes.

Project Sponsors

National Science Foundation




Avian malaria, House wren, Hemoglobin, Haemosporidia, Peru, Andes

Document Type


Degree Name


Level of Degree


Department Name

UNM Biology Department

First Advisor

Witt, Christopher

First Committee Member (Chair)

Loker, Eric

Second Committee Member

Hanelt, Ben