Benthic marine invertebrates have a variety of larval types that
range from non-dispersing brooded or encapsulated embryos to planktonic
forms that can passively disperse in the water column for months.  The
consequences of different dispersal abilities for population structure and
speciation rates have been generally tested, but the specific patterns of
gene flow in different oceanographic situations have not been addressed.
For example, how sensitive are long-term gene flow patterns to temporal
variability in local oceanographic conditions?
	I will present a simulation model of dispersal using the
intertidal gastropod _Littorina_ that can track gene flow over many
generations.  Using a geographically simple stretch of coastline, I will
use the model to examine the effects of temporal changes in ocean currents
on genetic structure of a _Littorina_ population.