Journal: International Journal of Plant Sciences
Volume: 165
Pages: 69-83


Biogeographical and paleontological studies indicated that some ancient Gondwanan taxa have been carried by the rafting Indian plate from Gondwana to Asia. During this journey, the Indian island experienced dramatic latitudinal and climatic changes that caused massive extinctions in its biota. However, some taxa survived these conditions and dispersed ‘‘out of India’’ into South and Southeast Asia, after India collided with the Asian continent in the Early Tertiary. To test this hypothesis, independent estimates for lineage ages are needed. A published rbcL tree supported the sister group relationship between the South and Southeast Asian Crypteroniaceae (comprising Crypteronia, Axinandra, and Dactylocladus) and a clade formed by the African Oliniaceae, Penaeaceae, and Rhynchocalycaceae and the Central and South American Alzateaceae. Molecular dating estimates indicated that Crypteroniaceae split from their West Gondwanan sister clade in the Early to Middle Cretaceous and reached Asia by rafting on the Indian plate. Here we present molecular evidence from additional chloroplast DNA regions and more taxa to test the validity of the out-of-India hypothesis for Crypteroniaceae. Both clock-based (Langley-Fitch) and clock-independent age estimates (nonparametric rate smoothing and penalized likelihood) based on maximum likelihood analyses of three chloroplast DNA regions (rbcL, ndhF, and rpl16 intron) were used to infer the age of Crypteroniaceae. Our dating results indicate an ancient Gondwanan origin of Crypteroniaceae in the Early to Middle Cretaceous, followed by diversification on the Indian plate in the Early Tertiary and subsequent dispersal to Southeast Asia. These findings are congruent with recent molecular, paleontological, and biogeographic results in vertebrates. Within the biogeographic context of this study, we explore the critical assignment of paleobotanic and geologic constraints to calibrate ultrametric trees.