Revisiting the phylogeny of Primulaceae s.l. using whole plastid genomes: Highlighting phylogenetic conflicts and their implications

Abstract The family Primulaceae s.l. is estimated to comprise approximately 60 genera and 2600 species worldwide. Although extensive research has been conducted on the family Primulaceae and its subfamily boundaries, there is a lack of systematic studies utilizing complete plastid genome data, leading to uncertainties in the phylogenetic positions of certain key taxa, such as Stimpsonia . In this study, plastid genomic data were collected from 67 accessions representing four subfamilies and 28 genera within the Primulaceae family. Phylogenetic trees were constructed using coalescent and concatenated approaches to elucidate the evolutionary history of the family. By employing a comprehensive dataset of 67 plastid genomes from all four subfamilies, a robust phylogenetic framework for the family was established. Contentious relationships were identified at the early stages of divergence in Primula and among Cyclamen and its relatives, probably due to rapid diversification. Our plastid genomic data support the idea that Stimpsonia is sister to the remainder of the subfamily Primuloideae, in contrast with its placement in Myrsinoideae based on nuclear data. A cytonuclear discordance in the phylogenetic position was also detected in Aegiceras corniculatum . The divergence time estimates from this study align with previous findings, indicating significant diversification events during the Eocene and Oligocene epochs. These timeframes coincide with major geological and climatic changes, which were likely to have influenced the distribution and diversification of Primulaceae. These results underscore the complex evolutionary history of the Primulaceae family and lay the groundwork for future research aimed at unraveling the intricate evolutionary dynamics within this family.