Peter Dunn

University of Wisconsin - Milwaukee

We study the ecology and evolution of reproductive behavior in birds. We are particularly interested in extra-pair mating, which occurs when individuals mate with individuals ‘outside’ their supposedly monogamous relationships. In most birds extra-pair males only provide sperm – they do not help with parental care.  Thus, if females are choosing to mate with these males, then the potential genetic benefits of sperm from another male are likely to be small.  So why is extra-pair mating so common in birds? One explanation is that females gain better (‘good’) genes for their offspring that enhance their immunity or attractiveness, but finding these genes has been difficult.

Major Histocompatibility Complex (MHC)

One gene family that has been of great interest is the Major Histocompatibility Complex (MHC), because it plays a key role in recognizing foreign pathogens and it is also been linked to mate choice.


In two populations of the common yellowthroat we have found that females prefer to mate with males that have lager or more colorful ornaments, and these ornaments are also associated with MHC variation, oxidative stress and survival (Dunn et al. 2013, Whittingham et al. 2015).

Immune genes & Grouse Conservation

Latest News

Bird Color paper published in Science Advances

(27 March 2015)






Popular News coverage:

Audubon, The Science Times, Daily Mail


MHC in Yellowthroats paper published in Molecular Ecology (17 March 2015)







Glen Bartley photo


Zach Bateson awarded NSF Doctoral Dissertation Improvement Grant

( 22 January 2015)

Congratulations Zach !



Interestingly, the ornament preferred by females differs between populations. In Wisconsin, females prefer mates with larger black masks, but in New York females prefer males with larger or more saturated yellow bibs.  Thus, the target of sexual selection differs between populations, but in either case the ornament preferred by females is a reliable indicator of male health and vigor.  Just as predicted by Hamilton and Zuk.


Home People Projects Publications

Our previous research on greater prairie-chickens indicated that population decllines (bottlenecks) can lead to loss of MHC variation. We are now examining other species and other types of immune genes to see if this is a widespread pattern.  In collaboration with Dr. Jeff Johnson at the University of North Texas, we are also studying how immune gene variation affects individual survival in the critically endangered Attwater’s prairie-chicken.  


Our second major project examines the immune genes of threatened species of prairie grouse. We are examining the effects of population size on variation at the MHC in prairie-chickens, sharp-tailed and sage grouse.

Why are Birds Bright and Colorful ?