Molecular phylogenetic tools reveal the phytogeographic history of the genus Capparis L. and suggest its reclassification

Abstract

Capparis is the largest genus of the family Capparaceae, represented by 142 species in the tropics and subtropics of the Old World. Despite being one of the medicinally and economically important genera with its unique distribution pattern, the evolutionary history of Capparis remained unexplored. Moreover, the phylogenetic relationships, origin, dispersal, and character evolution of the genus were poorly understood. With the objectives to (i) test the congruence between the molecular and morphological datasets, (ii) validate Jacobs' hypothesis on the origin, dispersal, and speciation pattern of Capparis using new fossil data, and (iii) understand the possible evolutionary role of some key morphological characters, we sampled across the five speciation centres of Capparis. The results derived from three plastidial markers (matK, trnL-F and rbcL) revealed incongruence with the morphology based delimitations and suggested a new sectional classification in Capparis. Divergence dating analysis revealed that Capparaceae originated in Africa at 47.25 MYA and Capparis in Peninsular India at about 29.32 MYA. Capparis followed multiple forward and backward dispersal, supporting the “into and out of India” hypothesis. These dispersal events were consistent with the various land bridges in different parts of the Old World during the Eocene to Miocene. The only long-distance dispersal event was observed in the case of the New World Capparaceae, corroborating the earlier findings. Our results suggest West Asia to the North African region as another centre of speciation for Capparis and present a robust age estimate for the genus. The character state reconstruction of Capparis revealed a unique evolutionary adaptation due to exposure to various climatic conditions and the acquisition of suitable pollination strategies. We hypothesize that the gynophore length, sepal shape, and blotches on petals contribute substantially to the pollination success.