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Model Structure: An individual maximizes reproductive success at each time step. Each time step in the model (t) corresponds, for simplicity, to a single reproductive period. There are several state variables that affect the individualβs reproductive success: the energy state of the individual, xt; the circulating hormone signal, Ct; and the sensitivity at each target tissue, 1 through i (S1,t,β¦, Si,t). An individual starts with a certain state value for its energy state, X0, circulating hormone level (C0) and sensitivity at each target tissue, 1 through i (S1,0,β¦, Si,0). An individualβs state at each time step t is defined by the state vector: The organism must solve the problem of how to optimally allocate its limited energy resources to maximize its fitness payoffs (Wt). The trait value (Vi,t) at each tissue and the selection on the trait (zi) determine the fitness payoffs to the organism. ππ‘ = π½π‘ (ππ,π‘ ) π§π,π‘ (ππ,π‘ ) π§π,π‘ (ππ,π‘ ) π§π,π‘ Several stochastic variables drive the simulation as well. The mortality rate (µ) is a fixed chance that the individual will not survive the given time step. Reproductive efficacy is modeled as a betadistributed random variable (Ξ²). ππ‘ πΆπ‘ π₯Μ π‘ = π1. .. . [ ππ ] The individual maximizes lifetime reproductive success by choosing the optimal adjustment in hormone levels (ΞCt) and sensitivities (ΞSi,t) at each time step. Constraints exist on the available energy of the individual (i.e. it must be above a certain level for any reproductive success (G, xrep), and it must be above zero for the individual to survive). An individualβs reproductive success in a given time step is a function of multiple hormonally-mediated characters. The value (Vi,t) of each trait is a function of the sensitivity of the target, Si,t and the circulating hormone signal, Ct. The relationship between these variables and the biological response is described by the simplified version of the Michaelis-Menken equation, according to the following expression: ππ,π‘ = ππ,π‘ πΆπ‘ πΎ + πΆπ‘ In the specific case being considered, we assume that reproductive success is a function of three hormonally-mediated characters: gamete maturation, mating effort and parental effort (Vg,t, Vm,t, and Vp,t). Parameter terms for the dynamic state model State Variables x Energy state Ct Circulating level of hormone at time t Si Sensitivity at target tissue i Static Parameters G Minimum hormonal state permissive of gamete maturation xrep Minimum body condition permissive of reproduction |ΞCmax| Absolute value of the maximum possible change of Ct |ΞSi, max| Absolute value of the maximum possible change of Si zi Selection index on trait i Ξ³i,t Cost of effort expended on each trait i Ο Food availability, e.g. encounter rate K Michaelis-Menten constant, e.g. dissociation rate Ξ· Cost of hormone production Stochastic Parameters Ξ² Random state variable reflecting reproductive efficacy at time t µ Mortality probability