South P acific biogeography, tectonic calibration, and pre‐drift tectonics: cladogenesis in A brotanella ( A steraceae)

Abrotanella is the basal genus in the large tribe S enecioneae ( A steraceae) and has a disjunct distribution in A ustralasia and S outh A merica. A recent molecular phylogeny of the genus was used to investigate whether the main biogeographical patterns in the group could be related to the region's tectonic history in a coherent way. The phylogenetic/biogeographical breaks and overlaps in the genus imply a series of vicariance and range expansion events. Each of these can be related to one of the main tectonic events in the region, including assembly of the N ew Z ealand terranes, crustal extension, and magmatism in G ondwana that preceded seafloor spreading, opening of the T asman and P acific basins, and transcurrent movement on the N ew Z ealand A lpine fault. The coincident sequence indicates that pre‐drift tectonics and magmatism have been more important for the origin of trans‐ T asman and trans‐ P acific groups than the final rifting of G ondwana that led to their disjunction. For example, during the pre‐drift phase of break‐up, the W hitsunday volcanic province of A ustralia and the M edian B atholith of N ew Z ealand formed a large, active igneous belt. Its distribution is aligned with the break between N ew Z ealand–south‐eastern A ustralia clades, and N ew Z ealand– N ew G uinea clades. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society , 2012, ••, ••–••.