|Two-sex models: demography, invasions, and perturbation analysis|
Michael Neubert, Stephanie Jenouvrier
Believe it or not, most population models ignore sex. This strange omission works because, often, the reproductive output of females is not limited by the abundance of males. But when that assumption fails, both species must be included in a demographic model. Such models are inherently nonlinear, because the per-capita reproductive rate depends on the population structure. However, they are usually nonlinear in a way subtly different from the nonlinearities that arise from density-dependence, resource limitation, or predator-prey interactions: the models are homogeneous. That means that they depend only on relative proportions of the stages in the population, not the absolute abundance. My research on two-sex models is currently focusing on developing models to incorporate details of breeding behavior, on perturbation analysis of population structure and growth rate, and on the effect on the speed and success of biological invasions.