THE REACTION PROGRESS VARIABLE IN ISOTOPE ECOLOGY

The reaction progress variable in isotope ecology provides important constraints on reaction rates and mechanisms. Use of the variable provides the opportunity to combine different experimental schemes and can be used to plan sampling campaigns. Multi-rate constants can be solved and this can allow a more realistic reconstruction of the history of individual behavior. In combination with the mass transport equation, complicating factor such as growth rates can be accounted for. We provide examples of multi-rate constants, direct determination of dietary histories, and physiological delay periods, all determined from the reaction progress variable approach.