Spatial models for hybrid zones

We introduce a spatially explicit model of natural hybrid zones that allows us to consider how patterns of allele frequencies and linkage disequilibri a change over time. We examine the influence of hybrid zone origins on patt erns of variation at two loci, a locus under selection in a two-patch envir onment, and a linked neutral locus. We consider several possible starting c onditions that represent explicit realizations of two alternative scenarios for hybrid zone origins: primary intergradation and secondary contact. Our results indicate that in some circumstances, differences in hybrid zone or igins will result in substantially different patterns of variation that may persist for thousands of generations. Our conclusions are generally simila r to those previously derived from partial differential equations, but ther e are also some important differences.