When we looked at temporal variation, we observed
that the genetic makeup of samples taken from Charleston
Harbor, South Carolina over 4 years showed little differentiation,
while the two samples taken from the Mississippi
River Delta, Louisiana over 2 years were significantly different.
These results mirror the geographical and temporal
genetic patchiness exhibited occasionally in other organisms
(e.g. McMillen-Jackson et al. 1994; Moberg & Burton
2000), and attributed to patchy settlement and further
selection as well as to high reproductive variance.