Ecological Archives E089-146-A1

Gil Proaktor, Tim Coulson, and E. J. Milner-Gulland. 2008. The demographic consequences of the cost of reproduction in ungulates. Ecology 89:2604–2611.

Appendix A. Reproductive strategies.

Individuals reproduce according to their pre-determined age-specific reproductive strategy. Each reproductive strategy is represented by a binary string consisting of a unique combination of 0 (not reproducing), and 1 (reproducing). A single value is allocated for each age from 2 through to 15, where age 15 is assumed to be the oldest possible age of a female. The value for age 1 is set to 0 for all females because red deer females do not reproduce before age 2 regardless of the conditions they experience. For example, a female with the strategy “001001111111111” begins to reproduce at age 3, does not reproduce at ages 4–5, and reproduces at all subsequent ages. Prior to the beginning of each simulation, six different reproductive strategies are created. These strategies are created randomly but with a limit of a maximum of seven values of 0 per strategy. This limit follows an initial inspection of the model output and permits reduction of computation time by avoiding searching low fitness combinations. Strategies are randomly allocated to an initial population of 120 individuals with a stable age distribution.

Each newborn inherits its life-time reproductive strategy from its mother with a 0.05 chance of mutation. A mutation results in one randomly selected age-specific reproductive strategy being changed from 1 to 0 or vice versa. A second type of mutation is the creation of a complete new random strategy. The chance of that mutation occurring is 0.005. These mutation rates are chosen following an initial inspection of the model convergence rates at a range of mutation rates.


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