Predominantly Eastward Long-Distance Dispersal in Pantropical Ochnaceae Inferred From Ancestral Range Estimation and Phylogenomics

Abstract

Ochnaceae is a pantropical family with multiple transoceanic disjunctions at deep and shallow levels. Earlier attempts to unravel the processes that led to such biogeographic patterns suffered from insufficient phylogenetic resolution and unclear delimitation of some of the genera. In the present study, we estimated divergence time and ancestral ranges based on a phylogenomic framework with a well-resolved phylogenetic backbone to tackle issues of the timing and direction of dispersal that may explain the modern global distribution of Ochnaceae. The nuclear data provided the more robust framework for divergence time estimation compared to the plastome-scale data, although differences in the inferred clade ages were mostly small. While Ochnaceae most likely originated in West Gondwana during the Late Cretaceous, all crown-group disjunctions are inferred as dispersal-based, most of them as transoceanic long-distance dispersal (LDD) during the Cenozoic. All LDDs occurred in an eastward direction except for the SE Asian clade of Sauvagesieae, which was founded by trans-Pacific dispersal from South America. The most species-rich clade by far, Ochninae, originated from either a widespread neotropical-African ancestor or a solely neotropical ancestor which then dispersed to Africa. The ancestors of this clade then diversified in Africa, followed by subsequent dispersal to the Malagasy region and tropical Asia on multiple instances in three genera during the Miocene-Pliocene. In particular, Ochna might have used the South Arabian land corridor to reach South Asia. Thus, the pantropical distribution of Ochnaceae is the result of LDD either transoceanic or via land bridges/corridors, whereas vicariance might have played a role only along the stem of the family.

Biogeographic history of the pantropical family Gesneriaceae with a focus on the Indian plate and diversification through the Old World

“…Vicariance and long-distance dispersal (LDD) are the two processes by which global biotic disjunctions can be explained, but these hypotheses can be difficult to distinguish for any particular disjunction. However time-calibrated phylogenies, especially when supported by near-complete taxon sampling, can address this question by determining the time and direction of movement between landmasses (e.g., Renner 2004a,b, Givnish et al 2004, Sytsma et al 2004, Buerki et al 2011, Olmstead 2013, Baker and Couvreur 2013a,b, Perret et al 2013, Armstrong et al 2014, Dupin et al 2016, Luebert et al 2017, Wu et al 2018, Schneider et al 2022. For pantropical plant groups, LDD is considered important but the role of island chains as potential stepping stones, and the precise routes employed, are still debated (e.g., Schneider et al 2022, Zhao et al 2022.…”

New Insights Into The Evolution of Chloroplast Genomes in Ochna Species (Ochnaceae, Malpighiales)

“…[5][6][7] Moreover, biogeography of Quiinoideae, an Ochnaceae subfamily, and divergence time for Ochnaceae were conducted. 8,9 For phylogenetic analysis, different data were employed, such as nuclear and chloroplast genomes. [10][11][12] Recently, phylogenetic relationships and new infrageneric classification of Ochnaceae have been proposed based on nuclear genes and exon data.…”