My research focuses on understanding the mechanisms of diversification at the level of species and populations, both spatially and temporally. In addition, I am applying the knowledge about past and current processes to predict how future environmental changes might influence levels of biodiversity and to develop improved ways of conservation prioritization. I developed new lines of research during my postdoc at UCLA, and intend to continue this work in the form of collaborations with researchers from the Center for Tropical Research and the Department of Ecology and Evolutionary Biology. Collaborative projects will consist of the following:
1) Mapping intraspecific variation of multiple species in the US and Africa
2) The environmental determinants of the occurrence and prevalence of infectious diseases, including avian influenza, West Nile virus, and human monkeypox
3) Identifying signals of selection in the wolf genome
4) The relative roles of selective and neutral evolutionary processes in the divergence of island bird populations
I have also studied the processes of allopatric speciation in Pacific honeyeaters and reed warblers, and worked on various conservation biology projects. In addition, I am interested in the biology of the African rockfowl, Picathartes.Conservation Biology
One of the most enigmatic and elusive birds of the African tropical forests is the rockfowl. Two species are currently recognized, and both are vulnerable to extinction. Rockfowl are colonial breeders near rocky outcrops in the forest. These rocky outcrops are not abundant, which make them essentially islands in the forest. Few is known about the biology of rockfowl, such as breeding biology, behavior, and genetics. I am particularly interested in their population genetics: how much variation is present within populations, how much do populations diverge, and to what extent is there gene flow between populations? In addition, I am interested to find out if and how these birds move from one breeding colony to another. This knowledge will be crucial in establishing conservation efforts for these birds.
The origin of species is a recurring theme, central to evolutionary biology. The process of speciation may be driven by sexual selection, ecological selection, or random drift, and the geographic constellation may vary from sympatry (no geographic isolation) to complete allopatry (geographically isolated by means of any barrier, such as water, mountains, or other unsuitable habitat). It has become clear through many empirical and theoretical studies that sexual and ecological selection can drive speciation in sympatry, but at the same time comparative studies show that allopatric speciation is much more common. Due to the historic pathway of scientific effort, we now know a lot about what rarely happens, and we know relatively little about what often happens. Although we have nice examples of allopatric speciation likely driven by ecology in Darwin’s finches of the Galapagos and the honeycreepers of the Hawaii islands, we do not have a thorough understanding of the processes driving allopatric speciation. In particular, we have little insight into the importance of sexual selection relative to changes through random drift. Island birds lacking obvious patterns of ecological divergence are well-suited to fill in this gap.
Vocalizations are the peacock’s tail of honeyeaters and reed warblers, and acoustic sexual selection is a classical model of studies on speciation in birds. In addition, the honeyeaters’ bright plumage indicates that –besides song- it may also be used in mate attraction and partner selection.
Five island populations in the Pacific were sampled for so far. Blood samples, external morphological characteristics, and song recordings will give insight in their genetic, morphological, and behavioral variation respectively. Plumage coloration differs markedly among the various island populations, not only across the entire Pacific (assessed from museum collections), but also within Micronesia. Second, song also varies noticeably among islands, and again even within Micronesia. Most notably, dawn song of the Pohnpei subspecies is distinctively different from the dawn song of other subspecies. I found more uniquely different motives in the Pohnpei population, and these motives are combined in all sorts of ways resulting in a variety of different phrases. This is in contrast to the songs of the remaining populations studied that possess a smaller repertoire of different motives and different phrases. Genetically there are slight differences in mitochondrial DNA, and the different populations are expected to show considerable divergence in microsatellites and SNPs. Once the behavioral, morphological, and genetic variation and divergence has been fully analyzed, I will assess mating preferences in the field.
I am grateful to the following institutions that provided funding for my 2006 museum visits and field trip to the Pacific: American Museum of Natural History Collection Studies Grant; Alida B. Buitendijk Foundation (Naturalis); Netherlands Organisation for Scientific Research Travel Grant; Society for the Advancement of Research in the Tropics (Treub-Mij); Systematics Research Fund. Special thanks go out to the following people for their help and collaboration: Prof. Joel Cracraft (American Museum of Natural History, New York); Dr. James Dean (Smithsonian Institution, Washington); Dr. Beth Flint (USFWS Pacific Remote Islands); Dr. Scott Fretz (Hawaii Division of Forestry and Wildlife); Dr. Joy Hiromasa (USFWS Pacific Islands); Ms. Shelly Kremer (Division of Fish and Wildlife, CNMI); Dr. Craig Ludwig (Smithsonian Institution, Washington); Mark MacDonald (M.Sc. University of New Brunswick); Dr. Annie Marshall (Fish and Wildlife Biologist USFWS, Pacific Islands Office); Dr. Rufino Mauricio (Historic Preservation Office FSM); Dr. Tony Otto (Historic Preservation Office FSM); Dr Douglas Pratt (North Carolina Museum of Natural Sciences); Ms. Karen Rosa (U.S. Fish and Wildlife Service Honolulu); Dr. Paul Sweet (American Museum of Natural History, New York); Dr Jeremiah Trimble (Harvard Museum of Comparative Zoology); Dr. Eric VanderWerf (U.S. Fish and Wildlife Service Honolulu); Ms. Linda Williams (Division of Fish and Wildlife, CNMI); Dr. Bethany Woodworth (USGS Pacific Island Ecosystems).