Rebecca E. Koch
Assistant Professor
University of Wisconsin-Stevens Point
Past Projects
A bird in the hand is worth...
...a lot of smiles. (And maybe a data point or two.)
In fall 2012, I joined Dr. Geoffrey Hill's lab group at Auburn University in Alabama. Dr. Hill's work on house finch coloration inspired my first research project as a high school student in Northern California. I've since graduated from his lab with a Ph.D.!
My first interests sparked in what I consider the most bizarre and varied of avian behaviors: sexually-selected displays of sound and color. My dissertation research expanded this interest beyond behavioral ecology, using physiological techniques to address why and how displays evolve--and more! See below for brief summaries of various projects I completed during my time at Auburn.
Core Ph.D. Research
The main results from my dissertation research are now published in Nature Communications! You can read the press release here, and a "Behind the Paper" story here.
Canaries represent a unique system where artificial selection has selected for color types with "knock-out" mutations that affect the ability to absorb carotenoid pigments from the diet and/or express them as plumage colorants. I focused on three color types:
1. White recessive canaries with no carotenoids in feathers and no circulating carotenoids.
2. White dominant canaries with no carotenoids in feathers, but with circulating carotenoids.
3. Yellow canaries with carotenoids in feathers and circulating carotenoids.
I tested the "Resource Tradeoff Hypothesis" for honest signalling by examining each color type's ability to respond to immune and oxidative challenges, given their variation in carotenoid absorption and processing.
I presented a poster on preliminary results from these experiments at Evolution 2016 in June, and updated the poster for NAOC in August 2016. And, I gave a more thorough update in an oral presentation at SICB 2017. I gave a final talk on the conclusions of this study at Evolution 2017.
A series of review papers, code-named "Mighty Mitochondria" and "Paraquat Problems"
Building off recent research in the lab, including Dr. Geoff Hill's recent ideas about the cellular basis of "condition" and the importance of mitochondria in sexual signaling, I am leading the research and writing of a new review paper, and have led the initial draft of a second; each delves deeply into biomedical research on mitochondrial interactions with important aspects of animal physiology, including immunocompetence (now published in Biological Reviews) and neurological function (also published in Biological Reviews!). By bridging the gap between the dense medical literature and the evolutionary ecology field, I hope to introduce organismal biologists like me to the substantial evidence supporting mitochondrial involvement in so many of the behaviors, mechanisms, and physiological processes we study.
In addition, my recent interest in determining a suitable oxidative damage challenge for my dissertation research on carotenoid pigments has led me to dive into a different niche of biomedical literature that examines the myriad effects of traditional oxidative challenges, like paraquat and diquat. The review paper has since evolved into a comprehensive discussion not only of the ill effects of bipyridilium herbicides like paraquat, but also the pros and cons of other currently used or potential oxidative challenges. This paper is now published in Functional Ecology!
Canary Mate Choice
I am working on assessing the results of tests for female domestic canary mate preferences for male song and color--the latter of which has never been investigated in this species, despite a rich literature testing the former (though never with live males).
Using snippets of song recorded from my birds at the AU Aviary and "stimulus" song clips from Dr. Tudor Drăgănoiu (France), I am using a factorial design to examine the influences of song quality, presence or absence of yellow coloration, ancestral green/yellow or supernormal red coloration, and their interaction on female mate choice.
The results of my study will be important both to better understanding the overall multimodal components of the male domestic canary canary, and to examine the competing signal strengths of songbird song and color in a highly controlled setting.
This research was funded by NSF DDIG! You may have seen me present preliminary results at the ABS conference in June 2015.
Searching for runaway sexual selection in bird art and museum specimens
In my first semester in Auburn, I embarked on a project in which I searched for evidence of rapid and dramatic plumage trait change in bird species over the past several hundred years. Given the powerful effects of human activities on the genetic makeup of species worldwide, I expected to find evidence of runaway selection triggered to radically modify ornamentation in some species of birds.
I analyzed hundreds of species depicted in accurate, pre-1900 bird illustrations and compared the phenotype of the historical bird to that of its modern counterpart. I also compared museum specimens of manakins and cotingas that were identical in species ID and geographic site of collection, but that differed in age by an average of ~70 years. I found no evidence of runaway sexual selection, and I explore the possibilities indicated by my data in a manuscript published in Ideas in Ecology and Evolution.
You may have seen me present this research at the SICB Conference in January 2013, at the ABS conference in July 2013, or in a poster at ISBE 2014!
Canary dichromatism and carotenoid coloration
I have been using spectrophotometry to analyze feather color in yellow and red factor lipochrome canaries. Building off the dietary supplementation experiment begun in 2011 by Hill Lab alumna Alex Halasz, I will evaluate how limited access to different types of carotenoid pigments affects canary coloration and feather pigment composition. Dr. Kevin McGraw from Arizona State University is assisting in the chemical analysis of feather carotenoid content. The manuscript of this research has been published in the Wilson Journal of Ornithology.
I also used museum specimens from the American Museum of Natural History to assess how the sexual dichromatism present in wild canaries has been lost in the centuries-long domestication of captive canaries. I presented the results of this study at the SICB Conference in Austin, TX in January, 2014, and the results of this project are published in the Wilson Journal of Ornithology.
