Phylogenetic affinity of an enigmatic Rubiaceae from the Seychelles revealing a recent biogeographic link with Central Africa: gen. nov. Seychellea and trib. nov. Seychelleeae.
Biogeography
Conservation
Dispersal
Relictual lineage
Systematics
West Indian Ocean
Journal
Molecular phylogenetics and evolution
ISSN: 1095-9513
Titre abrégé: Mol Phylogenet Evol
Pays: United States
ID NLM: 9304400
Informations de publication
Date de publication:
02 2020
02 2020
Historique:
received:
19
07
2019
revised:
30
09
2019
accepted:
12
11
2019
pubmed:
18
11
2019
medline:
11
6
2020
entrez:
18
11
2019
Statut:
ppublish
Résumé
The granitic islands of the Seychelles harbor about 268 native angiosperm species, with 28% being endemics there. The Seychelles biota contains a mix of ancient taxa with Gondwanan origins and young taxa that arrived there via dispersals. We investigate the phylogenetic position of an enigmatic, critically endangered, Seychellean endemic of the coffee family (Rubiaceae), Psathura/Psychotria sechellarum, and assess whether its presence on the granitic islands of the Seychelles is the result of vicariance or long-distance dispersal. Phylogenetic relationships of the family were reconstructed based on the Bayesian and maximum-likelihood phylogenetic analyses of sequence data from five plastid markers of 107 terminals. Divergence times were estimated using a Bayesian-based method. Psathura/Psychotria sechellarum is distantly related to Psychotria s.l. (including Psathura), and is strongly supported as sister to the Central African genus Colletoecema. Their striking morphological differences, coupled with their geographic separation and genetic distinctness, support the recognition of the new genus Seychellea and new tribe Seychelleeae to accommodate the Seychellean species. The Colletoecema-Seychellea clade constitutes an early-divergent lineage in the subfamily Rubioideae, with an old stem and a young crown ages estimated to be in the Late Cretaceous and late Oligocene-early Pliocene, respectively. Colletoecema diverged from Seychellea in the late Oligocene-early Pliocene and their respective crown ages are inferred to be late Miocene-middle Pleistocene and Pleistocene, respectively. The ancestor of the two genera was likely present in Africa, and reached the Seychelles via avian dispersal. Unlike Colletoecema with three species, Seychellea is monospecific, with very few individuals left in the wild. The species should be a top candidate for conservation priority, as its extinction would cause loss of genetic diversity of this entire lineage.
Identifiants
pubmed: 31734453
pii: S1055-7903(19)30449-X
doi: 10.1016/j.ympev.2019.106685
pii:
doi:
Types de publication
Journal Article
Research Support, Non-U.S. Gov't
Langues
eng
Sous-ensembles de citation
IM
Pagination
106685Informations de copyright
Copyright © 2019 Elsevier Inc. All rights reserved.