CAREER: Integrating Evolutionary and Mechanistic Investigation of Variation in Cooperation and Life History

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Cooperation is a key part of many complex animal societies, but even within close-knit groups some individuals cooperate more than others. We now know individuals may benefit from cooperation in several ways, but mechanisms underlying decisions to cooperate and variation in the amount of cooperation remain incompletely understood. The lance-tailed manakin provides an excellent opportunity to investigate why individuals vary in cooperative behavior, and how cooperative and non-cooperative behaviors coexist. Males of this tropical bird cooperate with non-relatives in coordinated courtship displays, but only dominant alphas mate. Some males serve long terms (6+ years) as non-breeding betas, while others become alphas without ever being betas. Both highly cooperative and non-cooperative males breed once alpha, but males cooperating for the average number of years have low alpha success. This project will assess the role of territory quality, genetic variability, phenotypic plasticity and bet-hedging strategies on beta male behavior. Undergraduate and graduate students and postdoctoral trainees will all be involved in lab and field work in the U.S. and Panama. This work integrates research and education by (1) implementing an international field course for undergraduates that combines involvement in long-term research with student-designed projects; (2) hosting three undergraduates for REU projects in Panama; (3) developing outreach exercises for 4th-6th graders; (4) publishing educational resources and establishing an associated webcam; and (5) establishing an educational display on the field site, visited by 8000-10,000 tourists/yr. This project investigates mechanisms underlying behavioral variation in cooperation in the lance-tailed manakin. It assesses the role of ecological constraints, experimentally quantifying effects of territory quality on beta behavior, and tests three complementary hypotheses explaining the occurrence of disruptive selection: genetic variability, phenotypic plasticity, and bet-hedging in unpredictable environments. The project quantifies additive genetic variance in cooperation using animal models on behavioral histories of pedigreed males. Effects of individual phenotype on life history and cooperation are investigated by measuring the relationships of condition, stress responsiveness, and telomeres (repeated nucleotides on chromosome ends, implicated as bioindicators of physiological state). Measures of lifetime siring success will yield insights about whether cooperators reduce variance in lifetime reproductive output. The project will train one postdoctoral researcher, at least one graduate student, and 15 postgraduates in field, laboratory, and analytical techniques. This project provides insight into both the function of cooperation by delayed direct benefits and the forces underlying disruptive selection on behavioral phenotypes. All data from the study will be archived at the Florida State University, and metadata associated with publications will be archived on Dryad.org. Databases will furthermore be accessible through a data repository held at the Smithsonian developed as part of the Manakin Research Coordination Network.