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Graduate Students and Postdocs
Colin Brent, Postdoctoral Researcher
Rebecca Clark, Ph.D. student
Matthieu Dacher, Postdoctoral Researcher
Dina Grayson, Ph.D. student
Tate Holbrook, Ph.D. student
Kate Ihle, Ph.D. student
Joe Latshaw, M.S. student
Tim Linksvayer, Postdoctoral Researcher
Brendon Mott, M.S. student
Oliver Niehuis, Postdoctoral Researcher
Rick Overson, Ph.D. student
Adam Siegel, Ph.D. student

Colin Brent

Postdoctoral Researcher
Ph.D., 2001 Boston University

My research focuses on the mechanisms regulating reproduction and caste development in a variety of social insects. I examine the behavioral, hormonal and physiological changes in insects as they mature, and the endogenous and exogenous stimuli that regulate this transformation. I am particularly interested in how interactions with conspecifics are perceived and translated into developmental responses affecting the reproductive dynamics of a colony. This multidisciplinary research has both basic and applied aspects, and, by providing insight into the mechanisms that underscore colony reproductive dynamics, it is a crucial step towards understanding the context in which extreme social complexity can arise.

Although most of my research has focused on the development of ants and termites, I am currently working with Robert Page and Gro Amdam to examine the hormonal regulation of behavioral and reproductive differentiation in honey bees. Adult worker bees exhibit temporal polyethism, displaying different suites of behaviors depending on their age and social environment. The timing and nature of these behavioral shifts appear to be under both genetic and hormonal control, and influenced by earlier organizational events occurring before adult emergence. These controls appear to have been derived from the basic ground plan for reproductive differentiation. Using selectively bred strains, we are exploring the long-term developmental and behavioral effects of differential endocrine activity during larval and pupal stages, while concurrently trying to isolate the neuronal and genetic basis of strain differences.

Rebecca Clark

Ph.D. student
Advisor: Jennifer Fewell

I study social insect nutrition and behavioral ecology, using species of ants that are native to Arizona to answer questions about processes affecting colony growth and fitness. One current project aims to understand how the division of labor in groups of ant queens affects colony survival and productivity in the seed-harvester ant Pogonomyrmex californicus. Additionally, I am working to understand nutrient flow in the desert leafcutter ant Acromyrmex versicolor, which uses leaves and grass to cultivate a fungus that serves as the ant's primary food source. I will be using a stoichiometric framework to clarify how this obligate ant-fungus mutualism allows ants to convert plant material that is relatively poor in available carbon, nitrogen and phosphorus to a nutrient-rich substrate that allows these ants to occupy an important ecological niche in the new world.

Matthieu Dacher

Post-doctoral research associate / Adjunct faculty
Ph.D., 2005, Tolouse III University (France)

Post-Doctoral Project: Role of inhibitory neural networks in honey bee olfaction

Restrained worker honeybee is a valuable model for studying neural networks that underlie olfactory processing. Indeed, this insect readily allows for the study of olfactory plasticity at both the behavioural and the neuronal levels. For instance, there is a high correlation between honeybee odour representation (behaviourally assessed by discrimination conditioning) and the neural activity in the antennal lobe (as assessed by calcium imaging). It is widely admitted that in the antennal lobe (the first relay of olfactory receptor neurons in the brain and an analog of mammals' olfactory bulb), at least two types of neural inhibition are important for processing input from olfactory receptor neurons. However, the exact roles of these inhibitory networks remain unknown.

To clarify this point, we propose begin with a complete study of the behavioural roles of various gabaergic and histaminergic drugs (putative blockers of the inhibitory processes), by injecting them in the antennal lobe during olfactory discriminative learning. We will then clone the honeybee genes coding for the subunits of two types of GABA receptors as well as for the histamine receptors, which are putatively involved in these inhibitory processes. This will allow us to product RNAi, which can be used as a molecular tool to investigate the role of different types of receptors in olfactory discrimination. Finally, we propose to combine pharmacological and molecular treatments with calcium imaging in the antennal lobe. The unique nature of this work lies in taking advantage of the possibility of recording neural events in combination with treatments designed to manipulate inhibitory processing. These data can then be correlated to results from behavioural studies using the same pharmacological and molecular treatments. Hence, the role of inhibitory networks in olfaction will be studied at various levels of analysis, from molecular to behavioural.

Dina Grayson
Ph.D. student
Advisor: Jennifer Fewell

My research interests include animal behavior, physiology, ecological stoichiometry, and invasive species. More specifically, my dissertation research focuses on evaluating some of the behavioral and physiological traits of the Africanized honey bee that help them out-compete European honey bees in the Southwest. The Africanized honey bee has spread both North and South throughout the Americas since it was first introduced to Brazil in 1957. Previous research has indicated that faster colony growth and reproduction of the Africanized honey bee has contributed to its successful invasion. However, it remains unclear how the resources necessary for faster colony growth and reproduction are obtained by Africanized honey bees. By comparing the foraging behavior of European and Africanized honey bees in the same environment I hope to elucidate some of those mechanisms.

C. Tate Holbrook

Ph.D. student
Advisor: Jennifer Fewell

I am a Biology Ph.D. student in Jennifer Fewell's lab. While still exploring potential directions for my dissertation research, I am generally interested in the behavioral ecology and evolution of social insects. Social insects are an excellent model system for studying the evolution of sociality because they exhibit a wide range of social organizations, are ecologically dominant, and are easy to manipulate. I am particularly intrigued by multiple mating, cooperative colony foundation, division of labor, and transitions in social evolution.

During my first year of graduate school, I have collected preliminary data on division of labor during colony foundation in the leafcutter ant Acromyrmex versicolor and collaborated with Drs. Jčrgen Gadau and Bob Johnson on a sociogenetic analysis of queen dimorphism and mating behavior in the harvester ant Pogonomyrmex (Ephebomyrmex) pima.

I completed a B.S. in Biology at the University of North Carolina at Asheville, where I investigated amphibian community ecology (Advisor: Dr. Jim Petranka) and katydid bioacoustics (Advisor: Dr. Tim Forrest). I then collaborated with Drs. Blaine Cole and Diane Wiernasz of the University of Houston on the sociobiology of the harvester ant P. occidentalis. I also enjoy teaching and intend to pursue an academic career that balances research and teaching.

Kate Ihle
Ph.D. student
Advisors: Gro Amdam and Rob Page

Joe Latshaw
M.S. student
Advisor: Brian Smith

Tim Linksvayer

Postdoctoral Researcher
Ph.D., 2005, Indiana University

I am interested in social evolution, particularly in the eusocial ants, bees, and wasps. Social insects are model systems for the study of social evolution, but little is known about the genetic architecture underlying social insect traits, which shapes evolutionary responses to selection. When social interactions occur, the phenotype of an individual is influenced directly by its own genes (direct genetic effects) but also indirectly by genes expressed in social partners (indirect genetic effects). Social insect colonies are characterized by extensive behavioral interactions among workers, brood, and queens so that indirect genetic effects are particularly relevant. For my Ph.D. thesis, I developed a formal indirect genetic effects model of social insect phenotypes and I estimated the relative contribution of direct and indirect genetic effects to mass, caste ratio, and sex ratio within a population of an acorn ant and to size differences between three species of acorn ants. The results demonstrate the importance of both direct and indirect effect genes, and the interaction between these classes of genes, to the evolution of social insect phenotypes. I am currently continuing to develop theory and experimentally study social evolution in ants and bees using an evolutionary genetics approach.

Brendon Mott
M.S. student
Advisor: Juergen Gadau

Brendon M. Mott is an Arizona native and received his Bachelor of Science in Biology from Arizona State University in May 2006. He is currently pursuing a MS in Biology at ASU and is working on several systems in the seed harvester ant genus Pogonomyrmex. His research interests are in the confluence of genetics and evolution. This includes both the genetic mechanisms of evolution and the use of genetic/molecular methods for studying population dynamics and behavior.

Oliver Niehuis
Postdoctoral Researcher

Rick Overson
Ph.D. student
Advisor: Juergen Gadau

Adam Siegel

Ph.D. student
Advisor: Rob Page

I am studying variation in the behavior and learning of selectively bred strains of the honeybee, Apis mellifera. These bees have been bred to collect different amounts of pollen. One project is looking at pre-foraging behavioral differences in these bee strains. I plan to follow this up with work on the mechanisms of these variations. Another project focuses on associative learning in the strains.

I obtained a B.S. in Biology at Tufts University in 2004, and am currently pursuing a Ph.D. at ASU.