Evolution in a metapopulation with space-limited subpopulations.

A model for the dynamics of a metapopulation with space-limited subpopulations (Roughgarden & Iwasa, 1985) is extended to include genetic variation for life-history traits. The traits include those expressed by the sessile adults in the space-limited subpopulations and traits expressed by the dispersing larvae. Conditions for increase of a new allele at a single locus are derived using two formulations, one that omits, and one that includes, age-structure among the sessile adults. From both formulations a criterion indicating the general direction of evolutionary change is derived: a new allele enters the population if it increases the average productivity of larvae from the subpopulations relative to the larval mortality rate, where the average is computed by weighting the productivity from each subpopulation by the amount of unoccupied space in it. This criterion may offer a start towards a theory for the evolution of life histories appropriate to the population structure of sessile marine invertebrates with pelagic larvae. In particular, the basal area of a sessile adult in a population with space-limited recruitment is a selectively neutral character.