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Eric Middleton

Graham Goodman
Graduate Student
Middleton Email
(801) 585-9742

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Background
As with many children around the world, I was first exposed to parasites at a young age. Despite an early introduction, it wasn’t until taking a course on parasitology at the University of Colorado that I was fully able to appreciate the complexity of host-parasite relationships. After graduating from CU, I went on to study elk, bats, crocodiles, and wolves, while completely ignoring the organisms that lived on, and in them. While elk and bats are charismatic, it wasn’t long before I missed the complex world of parasites and quit my job with wolves to study parasites once again.
Since joining the Clayton-Bush lab, I have focused my research on the relationship between parasites, the social environment, and behavior. The frequency of many self-directed ectoparasite defenses are not only influenced by the intensity of infestation, but also by other environmental and social conditions. While many self-directed behaviors are well studied, we know far less about cooperative ectoparasite defenses. One such cooperative defense may be allopreening. Allopreening is when bird preens another bird, and is thought to play important social and hygienic functions. My goal is to take an integrative approach to better understand the proximate and ultimate pressures that have shaped this fascinating behavior.

Current research
I am interested in investigating testing whether allopreening is an inducible ectoparasite defense and if the social environment influences the rate at which birds allopreen. Because allopreening requires partners to come into contact with each other, it is possible that it comes with inherent parasite related costs. I am also interested in better understanding how this pair-bonding behavior may also influence parasite transmission. Allopreening in action.

Study organisms
Pigeons (Columba livia) and their ectoparasitic feather lice (Columbicola columbae) offer a great opportunity to study allopreening because pigeons allopreen regularly, but also unidirectionally. That is, females tend to allopreen males but not vice versa. If allopreening strictly provides protection from parasites, it would be disproportionately valuable to males that will receive most of the benefit. Allopreening may be a commodity that can be traded for itself or in exchange for other services from the male. For example, allopreening may be valuable for males as it reduces ectoparasite loads, and valuable for females because it may help reinforce monogamy or promote male protection. In this system, males invest heavily in parental care, and single females are often harassed by bachelor males.

Why study allopreening?
A more comprehensive understanding of this behavior will allow biologists to begin asking big questions about cooperation, sociality, and how the adaptive functions of a behavior can interact with the social functions. For example, if allopreening rates increase with parasite intensity, and allopreening is important for maintaining pair bonds, having parasites may increase group cohesion and cooperation in some animal societies. Allopreening may have initially evolved to provide direct fitness benefits to monogamous pairs of birds and their offspring. However, once established, the behavior could be coopted to promote cooperation between non-related group members. This may be especially true for birds that form large groups, as these are associated with higher parasite loads. Furthermore, we can also ask questions about the evolutionary pressures that lead some species to allopreen reciprocally, while others allopreen unidirectionally. This is important as we increasingly find reciprocal altruism and kin selection to be insufficient in explaining the extent of altruism and cooperation seen throughout the animal kingdom. 

Broader impacts
In addition to basic research, I am interested in creating outreach and teaching materials related to biology. I have mentored several undergraduate and middle school students.  I firmly believe that the path to a more scientifically literate public and congress will rely on the next generation of voters.

Outside stuff
I enjoy running ultra-marathons, backpacking, skiing, and playing volleyball.

Publications:

Villa, S. M., G. B. Goodman, J. S. Ruff and D. H. Clayton.  2016.  Does allopreening control avian ectoparasites?  Biology Letters 12: 20160362. http://dx.doi.org/10.1098/rsbl.2016.0362. PDF