Consequences of life-cycle complexity to the potential for evolutionary branching

Complex life-cycles - that is, organismal development that unfolds across ecological niches - are pervasive in nature. In this work we set out to investigate the effects of complex life-cycles on the potential for diversification via evolutionary branching. We did this by analyzing a mathematical model of a consumer with two life-stages, each of which is characterized by a specific feeding efficiency trait that undergoes evolutionary change in response to ecological conditions such as resource competition. We find (i) that life-cycle complexity can favor diversification when compared to simple life-cycles, as there is a larger potential for evolutionary branching in the trait of the life-stage that has a higher population density; (ii) that evolution favors character displacement to minimize intra-stage resource competition; and (iii) that under certain parameters more than one evolutionary branching event can occur.