Associate Professor of Biology
Dr. Knapp's web page
Current Research Interests and Subject Areas Available for Graduate Research
I am interested in understanding the physiological, ecological and evolutionary factors contributing to behavioral variation, with an ultimate aim of increasing our understanding of how behavior evolves. Research in my lab combines the approaches of behavioral endocrinology, neuroendocrinology and physiological ecology to study the bases of behavior by studying animals in both the field and laboratory. We ask questions related to the physiological bases of variation in aggressive and reproductive behavior, with two main foci: 1) variation in androgen-glucocorticoid interactions in the context of alternative male reproductive tactics and 2) endocrinology of male parental behavior. The focus has been on steroid hormones because of their important role as chemical messengers that mediate behavioral, physiological and developmental processes. The concentration on interactions between the stress and reproductive endocrine axes is because these axes mediate some of the major costs and benefits associated with male reproductive behavior.
Alternative male reproductive tactics
In species with discrete alternative reproductive tactics, males achieve reproductive success by one of two or more distinct tactics: a displaying, territorial tactic or one or more non-displaying “cuckolder” tactics. In many of these species, the behavioral variation is tightly correlated with morphological variation, with one male “morph” exhibiting the entire suite of sexually dimorphic characters typically considered male-typical and one or more morphs that are female-like in the expression of some secondary sex characters. These species have traditionally received much attention in the behavioral ecology literature, but little is known about the physiological mechanisms contributing to such intra-sexual variation. My current efforts in this are area focused mainly on bluegill sunfish in collaboration with Dr. Bryan Neff (Western University, Ontario, Canada). Our current focus includes understanding morph-specific variation in behavior and spermatogenesis.
Male parental behavior
In many species of fish, the males provide all of the parental care. I am interested in how hormone-behavior relationships vary across species that differ in whether or not the males must simultaneously provide parental care and court additional females for spawning. Again, bluegill sunfish are our current main study species.
I welcome inquiries from students interested in various questions related to the physiological bases of variation in reproductive behavior. Although my own research is currently focused on fishes, students would not be limited to studying these taxa.
Ph.D., Arizona State University
M.S., University of Wisconsin-Madison
B.S., Cook College, Rutgers University
Member, Oklahoma Center for Neuroscience
Rodgers, C.M.C., B.D. Neff, and R. Knapp. (2013) Androgen-mediated nurturing and aggressive behaviors during paternal care in bluegill sunfish (Lepomis macrochirus). Hormones and Behavior, in press. doi: 10.1016/j.yhbeh.2012.12.008
Genova, R.M., M.A. Marchaterre, R. Knapp, D. Fergus, and A.H. Bass. (2012) Glucocorticoid and androgen signaling pathways diverge between advertisement calling and non-calling fish. Hormones and Behavior, 62(4): 426-432.
Knapp, R., and S.L. Carlisle. (2011) Testicular function and hormonal regulation in fishes. pp. 43-63 In (Norris, D.O., and K.H. Lopez, eds.) Hormones and Reproduction of Vertebrates. Vol. 1. Fishes. San Diego: Elsevier.
Knapp, R., E. Marsh-Matthews, L. Vo, and S. Rosencrans. (2011) Stress hormone masculinizes female morphology and behaviour. Biology Letters, 7: 150-152. doi:10.1098/rsbl.2010.0514
Scobell, S.K., A.M. Fudickar, and R. Knapp. (2009) Potential reproductive rate of a sex-role reversed pipefish over several bouts of mating. Animal Behaviour, 78: 747-753.
Neff, BD, and R. Knapp. (2009) Paternity, parental behavior and circulating steroid hormone concentrations in nest-tending male bluegill. Hormones and Behavior, 56: 239-245.
Knapp, R., and B.D. Neff. (2008) Alternative reproductive tactics in fishes. Pp. 411-433 in Fish Behaviour (Magnhagen, C., V.A. Braithwaite, E. Forsgren, and B.G. Kapoor, eds), Enfield, NH: Science Publishers Inc.
Leary, C.J., A.M. Garcia, R. Knapp, and D.L. Hawkins. (2008) Relationships among steroid hormone levels, vocal effort and body condition in an explosive-breeding toad. Animal Behaviour, 76: 175-185.
Knapp, R., and B.D. Neff. (2007) Steroid hormones in bluegill, a species with male alternative reproductive tactics including female mimicry. Biology Letters, 3: 628-631.
Leary, C.J., A.M. Garcia, and R. Knapp. (2006) Female toads and sexual parasites choose males with low levels of stress hormone: dynamic tradeoffs and potential constraints on sexually selected traits. American Naturalist, 168(4): 431-440.