Research

My current research specialization is integrating the field immunogenetics and genomics to answer questions on the evolutionary and behavioral ecology of vertebrates.

AVATAR_JOEL

Everything is better as a cartoon scientist. Follow me on Twitter: @EvoEcoJoel

Postdoctoral Research

While acoustic and visual cues are still important, chemical cues are coming into the forefront of communication in songbirds. Recent research, particularly from Dr. Danielle Whittaker, has shown that dark-eyed juncos (Junco hyemalis) respond to chemical cues from preen oil secreted by their uropygial gland. This candidate cue is involved in reproductive success in this species and may be mediated by microbial symbionts located in and around this gland. Alongside Dr. Whittaker, I am trying to unravel how host genotype controls the abundance and taxonomic groups of bacteria in the preen gland of this species.

My other research projects involve investigating the role of adaptive genes in host-pathogen interactions, and how these interactions are involved in population divergence, and animal conservation.

How do you take preen oil from a bird you ask? 

Graduate Research

Ph.D. (Supervisor: Beth MacDougall-Shackleton)

Thesis Abstract: In recent years, sexual selection theory has redefined genetic quality to consider not only additive genetic effects on fitness but also non-additive genetic effects, such as heterozygote advantage or disadvantage. In jawed vertebrates, the major histocompatibility complex (MHC) gene family has been shown to exhibit both additive and non-additive genetic effects on fitness. MHC gene products are involved in initiating adaptive immune responses, and MHC genotype determines the range of pathogens to which an individual can respond. Therefore, parasite-mediated selection at MHC may favour locally-adapted, rare, or particular combination of alleles. Because heterozygote advantage at MHC is widespread, sexual selection should favour mechanisms by which individuals assess the MHC genotypes of potential mates, and mate non-randomly. Studies exploring the role of MHC in immunity and sexual selection are widespread amongst mammals and fish, but in birds (especially songbirds) there is relatively scant evidence for MHC-mediated mating and the mechanism by which this might be accomplished remains unknown. First, I assessed differentiation at MHC class I and II that might underlie locally-good gene effects in two populations of song sparrows (Melospiza melodia) previously shown to exhibit higher resistance to sympatric malaria (Plasmodium) strains. I found no population differentiation, suggesting no locally-good gene effects at MHC, but individuals with higher class I diversity were less likely to be infected when experimentally inoculated with Plasmodium. Second, I explored whether song sparrows convey information on MHC class II genotype through chemical (preen oil) or auditory (birdsong) cues. Pairwise similarity at MHC was related to pairwise similarity of preen oil chemical composition, but not to pairwise similarity in song repertoire content. Song repertoire size, a sexually selected trait in this species, was nonlinearly related to MHC diversity, such that males with intermediate MHC diversity sang the most songs. Finally, to investigate MHC-mediated mate choice, I compared MHC similarity of socially mated pairs of free-living song sparrows to random expectations. Contrary to my prediction of MHC-disassortative mating, social pairs were more similar at MHC than expected by chance. This work emphasizes the importance of considering mate choice in the context of fitness effects at MHC.

website_schematic

My thesis investigated MHC in song sparrows. In particular, parasite-mediated selection at MHC, chemical and acoustic signals of MHC, and MHC-mediated mate choice. (song sparrow photo: Tosha Kelly)

MSc (Supervisor: Colleen Barber)

Thesis Abstract: Plumage spectral characteristics are thought to play an essential role in mate choice. Male and female birds may benefit from mating outside of their social-pair bond if they obtain genetic benefits for their offspring by choosing mates with plumage that signals individual high quality. The goal of this thesis was to test the hypothesis that male and female genetic quality is signaled through hackle spectral characteristics and used in mate choice decisions by European starlings (Sturnus vulgaris). Hackle brightness was positively correlated with female body condition and male provisioning effort. Also males with brighter hackles sired proportionally more male offspring than males with duller hackles. Purple hackles (Figure 1a, Figure 2) were positively correlated with male body condition and female realized reproductive success. This study demonstrates the importance of hackle spectral quality in European starlings and the role it plays in mate choice.

 

 

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s