Marine biogeographic disjunction in central New Zealand

We present a phylogeographic analysis of an abundant New Zealand endemic sea-star, Patiriella regularis, to help pinpoint the location of an important biogeographic disjunction in central New Zealand. The analysis incorporates 284 mtDNA control region sequences (approximately 800 bp) of P. regularis from 22 coastal locations around New Zealand. We detected 132 haplotypes, with a mean divergence of 0.96%. AMOVA analysis of New Zealand samples is consistent with a north-south biogeographic disjunction across central New Zealand (among-group genetic variance = 6.10%; P = 0.0005). Cook Strait, the shallow marine strait separating the main islands, is not correlated with the disjunction: samples from northern South Island are genetically indistinguishable from North Island samples (variance = 1.69%; P = 0.073). These results are consistent with the hypothesis that upwelling zones south of Cook Strait constitute a significant barrier to larval dispersal.