Timing transantarctic disjunctions in the Atherospermataceae (Laurales): evidence from coding and noncoding chloroplast sequences

Previous studies of the small Southern Hemisphere family Atherospermataceae have drawn contradictory conclusions regarding the number of transantarctic disjunctions and role of transoceanic dispersal in its evolution. Clarification of intergeneric relationships is critical to resolving (1) whether the two Chilean species, Laurelia sempervirens and Laureliopsis philippiana, are related to different Australpacific species, implying two transantarctic disjunctions as suggested by morphology; (2) where the group is likely to have originated; and (3) whether observed disjunctions reflect the breakup of Gondwana. We analyzed chloroplast DNA sequences from six regions (the rbcL gene, the rpl16 intron, and the trnL-trnF, trnT-trnL, psbA-trnH, and atpB-rbcL spacer regions; together 4,338 bp) for all genera and most species of Atherospermataceae, using parsimony and maximum likelihood (ML). The family's sister group, the Chilean endemic Gomortega nitida (Gomortegaceae), was used to root the tree....