Molecular evolution, genetic diversity, and avian malaria in the Hawaiian honeycreepers

Abstract

This dissertation is an interdisciplinary study linking molecular and population genetics to basic problems in island ecology, evolution, and extinction. The Hawaiian honeycreepers (Aves: Fringillidae: Drepanidinae) are extremely morphologically diverse and have radiated into nearly all of the passerine behavioral niches. The group is currently threatened with extinction by anthropogenic disturbances including introduced diseases. Basic biological problems in the honeycreepers include resolving systematic issues, documenting population structure and identifying the role of disease in limiting remaining populations. A molecular systematic study tested representative honeycreeper species for monophyly. I sequenced 13 honeycreeper species and used 3 outgroup taxa, 2 cardueline finches and a titmouse, for a 790 bp fragment of the mitochondrial cytochrome b gene. Phylogenetic trees constructed using distance, parsimony, and maximum likelihood methods all grouped the honeycreepers monophyletically and placed P. montana and O. bairdi in a basal clade. Two Ore0mYstis species were polyphyletic, indicating that they have been misclassified. The basis for this misclassification was strong convergence of morphological and behavioral characters associated with insectivory. A population study of mitochondrial cytochrome b DNA sequence variability was conducted at three scales; single locations, single islands, and multiple islands. Mitochondrial variation was found for four species living in a center of distribution that is surrounded by highly disturbed regions. In the multiple location study, diversity was found for the Common Amakihi (Hemignathus virens). The multiple island study showed that a population of Kauai Amakihi is phylogenetically distinct from those on Maui and Hawaii and that the Maui and Hawaii populations share mitochondrial haplotypes. No variation was detected in the highly mobile Iiwi (Vestiaria coccinea) sampled from the same islands. A PCR-based test for avian malaria was developed that detects the Plasmodium 18S rDNA. Quantitative Competitive PCR experiments established the sensitivity limits of the test. The PCR test was used to estimate prevalence of avian malaria in Hawaiian birds living at high elevations above the normal range of mosquito vectors. Malaria was highest in the nomadic Apapane (Himatione sanguinea) followed by the sedentary Common Amakihi (Hemignathus virens). Malaria was not detected in the mobile Iiwi (Vestiaria coccinea) .