Major histocompatibility complex (MHC) genes code for proteins that present pathogens to the immune system and therefore have a direct effect on how well an individual survives disease. Amazingly, these genes also influence mate choice in many vertebrates. In mammals and fish, the MHC alters body odor thereby allowing individuals to choose mates and recognize kin through the sense of smell. Individuals can optimize MHC genes in their offspring by choosing mates with 1) high MHC heterozygosity or diversity, 2) specific well-adapted MHC alleles, or 3) MHC genes that complement their own. Individuals with "good" MHC genes are more resistant to some diseases, but also may be more attractive. This is because MHC genes can influence, not only body odor, but also physical traits, such as antlers in deer, that are expressed to their fullest extent when an individual is healthy and in good body condition. These "condition-dependent traits" are often displayed and examined during mate choice decisions (imagine the peacock's tail). Combining fieldwork with molecular approaches, the proposed research investigates how MHC genes may influence condition-dependent traits and mating patterns in European starlings (Sturnus vulgaris) and takes a truly integrative approach to understanding behavioral, physiological, and genetic components of mate choice in birds. Results from this research are expected to have impact on a broad range of work relating to behavioral and molecular ecology.
Broader Impacts: European starlings were introduced to North America from Europe 150 years ago, and during this time, their numbers have dramatically increased. Studying how these birds choose mates and how their immune systems successfully adapt to new pathogens will lead to a deeper understanding of their biology that can be applied to methods for controlling their expansion. Parsing out the non-exclusive roles of MHC heterozygosity and specific alleles in disease susceptibility and resistance will provide insight into how avian populations, and vertebrates in general, deal with an increasing barrage of introduced pathogens as human impact increases across the globe. Because this research has applications to both behavioral and molecular ecology, this project piques the interest of a broad range of students. Two undergraduates have participated in field research for this project, and more will participate this field season. Students interested in genetics techniques will also have the opportunity to work closely on molecular aspects of this project. Because this research is conducted on dairy farms, where starlings are agricultural and economic pests, placing nest boxes around the outlying agricultural fields has had the surprising effect of reducing the numbers of starlings breeding in and around barns and has created a positive working relationship between the researchers and local farmers.
