1 Citation
Long-distance dispersal (LDD) of seeds plays an important role in the
plant migration to a new habitat and maintaining gene flow among
populations. Pantropical plants with sea-drifted seeds have achieved their
global distribution by LDD. However, the spatiotemporal processes to
achieve the wide distribution and the role of LDD in it have not yet been
investigated. In this study, we conducted phylogenomic analyses on the
plastome, genome-wide nuclear SNP, and low-copy gene data of Hibiscus
tiliaceus and its relatives. We conducted shotgun sequencing for
extracting plasome sequence and MIG-seq for a genome-wide SNPs genotyping.
The dated phylogeny showed that global expansion started approximately
four million years ago (MYA), and species diversification occurred 1 MYA.
Plastome phylogeny suggested the non-monophyly of the haplotypes in the
two widely distributed coastal species, H. tiliaceus and H.
pernambucensis. In contrast, genome-wide nuclear SNP phylogenies clearly
illustrated genetic segregation among species and/or geographical regions.
Ancestral polymorphisms in chloroplast genomes shared among distinct
species have remained below the range of rapid expansion and speciation of
marginal populations. This study demonstrated that the LDD of sea-drifted
seeds contributed to the rapid expansion and pantropical distribution of
sea hibiscus, and adaptation to local environment or isolation by regional
effect after LDD promoted speciation, suppressing gene flow.