HermaDEB: An evolutionary IBM for energy allocation in hermaphrodites

Size-advantage hypothesis models (SAH) allow an understanding of which sex occurs first and when the sex is changed in hermaphrodite species, through the optimal allocation of energy in terms of male versus female roles. Whereas sex allocation depends directly on how an organism allocates energy throughout its lifetime, the dynamic energy budget theory (DEB), describes the uptake and use of energy and nutrients, as well as the physiological organization throughout an organism's life cycle, including growth, maintenance, reproduction, and aging. We propose an evolutionary individual-based model to bridge the gap between metabolic models and the sexual allocation model. In this paper, we describe an individual-based model used to study the size at the time of a sex change/maximum size, i.e., Lratio and the most important physiological factors influencing size at the time of a sex change, Lchangei. We show that the fraction that determines how much to invest in somatic maintenance and growth, κ, the cost of the structure relative to the energy allocated to the soma, and the somatic maintenance rate coefficient are the most influential factors. We also show that the ratio between male and female gamete costs has very little influence on Lchangei and Lratio.