Ph.D. Student
Indiana University
Department of Biology
Jordan Hall 142
1001 E. 3rd St.
Bloomington, IN 47405
E-mail: nmgerlac AT indiana DOT edu
My Research in a Nutshell
My current research involves extra-pair behavior in female dark-eyed juncos (Junco hyemalis). Extra-pair behavior has been well-studied from the perspective of male behavior, but much less so from the female perspective. Dark eyed juncos have an appreciable rate of extra-pair young in their nests, although individual females vary from highly faithful (no EPYs) to highly unfaithful (all EPYs). I am examining 1) the predictors of this variation in female behavior, 2) the consequences of this behavior for the fitness of the female and the fitness of her offspring, and 3) the hormonal mechanism(s) underlying this behavior in females.
This research consists of two main components. The first component is the assembling and analysis of data from over 20 years of records collected on a single dark-eyed junco population. This long-term data set allows me a unique opportunity to examine multiple years of reproduction for the effects of female age, condition, mate choice, and breeding history on extra-pair behavior. Similarly, I can also look at components of lifetime fitness for females who engage in varying levels of extra-pair behavior, as well as for offspring that are the result of extra-pair vs. within-pair fertilizations.
The second part of my research consists of experimental manipulation of a free-living population of dark-eyed juncos at Mountain Lake Biological Station in Giles County in southwest Virginia. By administering implants of crystalline testosterone to female juncos, I can examine the effects of elevated hormone levels on reproduction, specifically extra-pair behavior, and its effects on fitness. I also plan to examine whether nestling immune response varies in extra-pair vs. within-pair offspring, as a measure of short-term fitness to complement the long-term fitness measures described above.