Data from: Sensory trait variation contributes to biased dispersal of threespine stickleback in flowing water

Gene flow is widely thought to homogenize spatially separate populations,
eroding effects of divergent selection. The resulting theory of
‘migration-selection balance’ is predicated on a common assumption that
all genotypes are equally prone to dispersal. If instead certain genotypes
are disproportionately likely to disperse, then migration can actually
promote population divergence. For example, previous work has shown that
threespine stickleback (Gasterosteus aculeatus) differ in their propensity
to move up- or down-stream (‘rheotactic response’), which may facilitate
genetic divergence between adjoining lake and stream populations of
stickleback. Here, we demonstrate that intraspecific variation in a
sensory system (superficial neuromast lines) contributes to this variation
in swimming behavior in stickleback. First, we show that intact neuromasts
are necessary for a typical rheotactic response. Next, we showed that
there is heritable variation in the number of neuromasts, and that
stickleback with more neuromasts are more likely to move down-stream.
Variation in pectoral fin shape contributes to additional variation in
rheotactic response. These results illustrate how within-population
quantitative variation in sensory and locomotor traits can influence
dispersal behavior, thereby biasing dispersal between habitats and
favoring population divergence.