Phylogenetic relationships of Cuban and Caribbean plumeria (apocynaceae) based on the plastid genome

Authors: TIERNAN, NICHOLE - Fairchild Tropical Botanic Garden; Nakamura, Kyoko; BURNS, CHRISTINA - Florida International University; JESTROW, BRETT - Fairchild Tropical Botanic Garden; OVIEDO PRIETO, RAMONA - Institute Of Ecology And Systematics; FRANCISCO-ORTEGA, JAVIER - Florida International University

Submitted to: Biological Journal of the Linnean Society, London
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/14/2023
Publication Date: 8/19/2023
Citation: Tiernan, N., Nakamura, K., Burns, C., Jestrow, B., Oviedo Prieto, R., Francisco-Ortega, J. 2023. Phylogenetic relationships of Cuban and Caribbean Plumeria (Apocynaceae) based on the plastid genome. Biological Journal of the Linnean Society, London. 397-412. https://doi.org/10.1093/biolinnean/blad042.
DOI: https://doi.org/10.1093/biolinnean/blad042

Interpretive Summary: Members of Plumeria, commonly known as frangipani, are trees and shrubs found in tropical gardens worldwide and prized for their charismatic flowers. The Caribbean Islands are considered a global hotspot of biodiversity, containing an extraordinary concentration of endemic plant species, exceptionally endangered by habitat loss and vulnerable to extinction. Plumeria species display high morphological variations and they occurs in a wide variety of ecological zones, from high-elevation montane rainforests [e.g. Plumeria marchii Urb. (Jamaica) and Plumeria montana (Cuba)] to serpentine montane slopes [e.g. P. krugii (Puerto Rico) and P. cubensis (Cuba)] and limestone mountainous regions. A genetic study using the complete plastid genome sequences found that most Plumeria species are native to the Caribbean Islands, with a few also found in Central America and northern South America. The study identified patterns of adaptive radiation and colonization routes within the region. This research provides a phylogenetic framework for future research, necessitating the inclusion of nuclear molecular markers and broader sampling. A more detailed analysis of the biogeography of Plumeria will be feasible with further sampling that will allow the determination of relationships between Caribbean and mainland species.

Technical Abstract: Plumeria L. (Apocynaceae) is a Neotropical genus mostly restricted to the Caribbean, which is cultivated in tropical gardens worldwide. Almost all ~27 species are endemic to the Caribbean Islands, except for four (Plumeria inodora Jacq., Plumeria obtusa L., Plumeria pudica Jacq., and Plumeria rubra L.) that are native to Central America and northern South America. Cuba harbours the largest diversity of the genus, with 13 endemic species. We present the first molecular phylogeny of the genus based on the nucleotide sequences of the complete plastid genome. Partial plastid genomes of 11 Plumeria species and one closely related species (Himatanthus sp.) were sequenced using long-PCR and next-generation sequencing. The recovered clades mostly grouped by single islands or closely neighboring islands. The phylogenetic relationships indicate patterns of adaptive radiation, with ecological shifts within these island-based clades and a west-to-east colonization route in the region. Plumeria rubra and Himatanthus sp. were resolved as sister to the rest of the genus. One unexpected finding was that P. pudica, a species restricted to the southern Caribbean Basin mainland, was recovered within the clade containing the Caribbean Island endemics, rendering the endemic group polyphyletic. Our study provides a phylogenetic framework for future studies that will need to include nuclear molecular markers and a more extensive sampling.