Tasmanian and Victorian populations of the fern Asplenium hookerianum result from independent dispersals from New Zealand

Abstract

The fern Asplenium hookerianum Colenso (Aspleniaceae) is indigenous to New Zealand and Australia. In New Zealand, it is widespread and genetically diverse, with 26 haplotypes previously identified for the chloroplast trnL–trnF locus. In Australia, A. hookerianum is currently known only from two small populations in Victoria and two in Tasmania. The present study assessed the diversity, relationships and biogeographic history of the Australian populations. A single trnL–trnF haplotype was identified in Tasmanian populations, and it was shared with populations in south-western New Zealand. The single haplotype found in Victorian populations was unique and most similar to a haplotype found in populations from central and eastern North Island, New Zealand. Relationships among haplotypes suggest that the two Australian haplotypes are derived within the group (not close to the root of the haplotype network) and only distantly related. This pattern is consistent with two independent dispersals of A. hookerianum from New Zealand to Australia. These findings are unique in providing evidence for more than one trans-Tasman dispersal event in a species of vascular plant.