Current Research
MHC-based mate choice in a songbird: mechanisms, hormonal correlates, and population patterns
The major histocompatibility complex (MHC), a gene family involved in immune function, has been shown to play a role in mate choice in several species, though studies to date have given varying results. MHC genotype may be detected via odor, in sweat and urine and mammals and potentially in preen oil in birds. Three mate choice hypotheses have been suggested: 1) inbreeding avoidance, as individuals with different MHC types will be non-relatives, 2) compatible genotypes, as disassortative mating will produce heterozygous and therefore fitter offspring, or 3) “good genes,” as condition-dependent traits may rely on underlying MHC genotype.
I am testing the following hypotheses in a well-studied songbird, the Dark-Eyed Junco:
1) female juncos evaluate potential mates using olfactory cues;
2) these olfactory cues communicate information about MHC genotype; and
3) population genetic patterns such as inbreeding influence MHC-based mate choice.
I am conducting a number of studies testing whether juncos can discriminate among individuals on the basis of olfactory cues. I am collaborating with Helena Soini and Milos Novotny of IU's Institute for Pheromone Research to examine individual variation in preen oil compounds. I am sequencing MHC Class I and II loci in juncos and we will test for covariation in MHC sequence and preen oil compounds.
Furthermore, we are examining potential morphological (such as plumage) and physiological (such as steroid hormone levels) correlates of MHC genotype to test whether good genes advertisement is occurring.
Finally, I am interested in whether an individual's "genetic landscape" influences mate choice. I am comparing mate choice patterns with respect to MHC in two populations in southern California: one that breeds in species-typical habitat with normal levels of gene flow, the other a recent urban colonist population that has been isolated for about 30 years. My work to date suggests that MHC-based mate choice is occurring only in the isolated population, perhaps as an inbreeding-avoidance mechanism.
This research is supported by grants from the Indiana Academy of Science, the American Philosophical Society, and Indiana University.
Past Research
Evolutionary Genetics of Kloss's Gibbons (Hylobates klossii):
Systematics, Phylogeography, and Conservation
This was my dissertation research at the City University of New York. (Download the full 3.0 MB dissertation pdf.) For this project, I investigated the genetic diversity of the Kloss's gibbon, endemic to the Mentawai Islands of Indonesia. These gibbons are a poorly studied species, and little is understood about their phylogenetic position within the gibbon radiation and patterns of genetic diversity within the species. The other endemic Mentawai primates (Macaca pagensis, Presbytis potenziani, and Simias concolor) have been suggested to be divided into two subspecies based on variation in coat color: one on Siberut in the northern end of the chain, and one subspecies on the three southern islands. The Kloss's gibbon shows no obvious variation, as all individuals are completely black. Furthermore, the primates of the Mentawai Islands are threatened by logging and hunting, and the conservation status of the Kloss's gibbon has not been evaluated since 1980.
I collected fecal samples from unhabituated gibbon groups at 7 sites on all four Mentawai Islands in 2001 and 2003. I also conducted population surveys based on loud calls (want to hear a Kloss's gibbon call?). I extracted DNA from the fecal samples and amplified and sequenced the hypervariable region I of the mitochondrial genome, and also genotyped the samples at six microsatellite loci.
Systematics: Based on mitochondrial D-loop sequences and their congruence with morphological and vocal characteristics as well as ND3-4 data, the Kloss's gibbon appears to be a recently derived member of the lar group of gibbons, clustering with the geographically close H. agilis and H. moloch, rather than a basal taxon as previous morphological studies have suggested (Whittaker et al 2007, PDF).
Phylogeography: Based on the mitochondrial data, the Kloss's gibbon shows no genetic differentiation between islands.
Conservation: Based on my surveys, there are 20,000-25,000 Kloss's gibbons remaining in the wild, with the largest proportion located on Siberut (Whittaker 2005, PDF). I evaluated the conservation status for all four Mentawai primate species and published a conservation action plan (Whittaker 2006, PDF). I assessed the conservation status of these species at the 2006 Asian Primate Red List workshop and their status has been updated in the 2008 IUCN Red List.
This research was funded by:
National Science Foundation
The Charles A. and Anne Morrow Lindbergh Foundation
Primate Conservation, Inc.
New York Consortium in Evolutionary Primatology
