Risk of infection
During incubation, birds are models of successful microbial inhibition and control; both incubation and the egg itself provide a remarkable network of antimicrobial defenses against microbial pathogens, many of which are known to cause infection in humans. My current work at the University of Akron is aimed to identify the mechanisms of this network.
I am interested in the chemical and physical antimicrobial features of eggshells. I am studying the success of eggshells with varying characteristics (antimicrobial concentration, porosity) at preventing microbial invasion and the role that abiotic factors may play in increasing susceptibility of eggs to infection.
I have been investigating some of the mechanisms of the remarkable network of antimicrobial defenses in a bird family (Aves: Megapodiidae) with an unusually high risk of egg infection. Megapodes avoid egg microbial infection despite the high microbial abundance in their mounds, Their eggshells are coated with a thick layer of mineral nanospheres that prevent bacterial attachment.
Collaborators: Darryl Jones, Hope Badawy, Matthew Shawkey
As in other animals, the colors of bird feathers are produced by a variety of pigment molecules, nanostructures, or a combination of both. This mechanistic diversity provides complex opportunities for natural and sexual selection on the many functions of plumage color. I am currently examining the morphology of feather melanosomes (melanin-containing organelles) using electron microscopy
Currently I am investigating the relationship between eggshell structure and nesting ecology in a wide sample of species. I am testing the hypothesis that eggs of birds nesting where microbial growth may be higher (e.g. wetter and warmer habitats) are more likely to evolve antimicrobial eggshells than those in less risky habitats.
Evolution of plumage color
Evolution of eggshell structure
Nest-site selection and incubation
By performing discriminant analyses on data from a wide range of bird species, we have been able to predict colors of both non-avialan dinosaurs and basal birds. Three of our recent published papers performing use these color reconstructions address questions about the evolution of color patterns and novel structural colors in the avian lineage.
Collaborators: Julia Clarke, Matthew Shawkey, Jakob Vinther, Li Quanguo, Gao Ke-Qin
Funding Body : NSF
In collaboration with Jakob Vinther we are exploring the range of color patterns seen in the mammals from the Messel deposit. Analyses of preserved melanosomes in fossils will allow us to reconstruct their color patterns and get a better understanding of the environment they lived in.
Collaborators: Jakob Vinther, Matthew Shawkey
Funding Body : National Geographic
Color patterns of early tertiary mammals
I have been interested in knowing how the physical environment, by constraining the way energy is gained and expended, determines the capacity of organisms to invest in reproduction, growth or in resistance to stress.
I have studied some of the different strategies that individuals follow during the various phases of bird reproduction such as nest-site selection, resource allocation during egg formation, incubation and chick rearing.
I find incubation especially interesting because it represents an energetically demanding event that can set limits to current and future reproductive success in birds. My PhD thesis investigated the importance of the thermal environment and nesting habitat on the reproductive performance of a sea duck, the Common Eider (Somateria mollissima) breeding in a cold environment.
I have also worked in a study looking at the way the environment of a developing individual can shape adult phenotype. Specifically, we looked at consequences of the elevation of stress hormone levels during development and how this affects reproductive effort/success on later stages in life using the zebra finch as model species. This project was performed in collaboration with Prof. Pat Monaghan, Prof. Neil Evans and Dr. Karen Spencer.
Long term effects of developmental conditions
In essence the questions of my project were 1) how does the nest site influence the microclimate of incubation, 2) what is the effect of microclimate on incubation performance? And 3) what role does the macroclimate play in population dynamics?