Figure 1

Sampling design. The black dots indicate the two sampling localities on the Great Barrier Reef: Lizard Island (14°40’S, 145°28’E) in the north and One Tree Island (23°25’S, 151°55’E) in the south. The thick solid arrow represents the distribution of Amblygobius rainfordi, and Chrysiptera rollandi, two species for which One Tree Island is near the southern margin of their distribution. The thin solid arrow represents the distribution of Amphiprion akindynos, the Lizard Island population of which is near the northern margin of this species’ distribution. The dashed line represents the distribution of the three congeneric control species whose ranges extend both north and south beyond the limits of the GBR. All species were sampled at the two locations indicated; the solid arrows are displaced for illustrative purposes.