EVOLUTION AND BIOGEOGRAPHY OF THE HEBE COMPLEX (SCROPHULARIACEAE) INFERRED FROM ITS SEQUENCES

The Hebe complex comprises a putatively monophyletic group distributed from eastern Australia and New Guinea to the Falkland Islands. Analys is of ITS sequences supports five distinct clades within the complex, corresponding to Derwentia plus Hebe formosa, Heliohebe, Chionohebe pl us Parahebe trifida, Parahebe, and Hebe. Hebe cheesemanii and Hebe cup ressoides form a weakly supported clade that is distinct from the Hebe clade. Relationships of Hebe macrantha are poorly resolved. The curre ntly recognised infrageneric classification of Hebe is not supported b y this study, and the newly described genus Leonohebe Heads is conside red polyphyletic. These results suggest that the progenitor of the Heb e complex originated in Australia. A rapid and extensive radiation fol lowed establishment of a founder population in New Zealand. The combin ed effects of inbreeding, genetic drift, and strong selection on small populations fragmented by mountain-building and glaciation have contr ibuted to its rapid evolution. At least two recent instances of long-d istance dispersal between New Zealand and South America are supported.