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Molecular phylogeny and adaptive radiation of the endemic Hawaiian Plantago species (Plantaginaceae)
Author(s) -
DunbarCo Stephanie,
Wieczorek Ania M.,
Morden Clifford W.
Publication year - 2008
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.3732/ajb.0800132
Subject(s) - biology , adaptive radiation , biological dispersal , paraphyly , monophyly , ecology , lineage (genetic) , evolutionary biology , phylogenetics , phylogenetic tree , population , clade , biochemistry , demography , sociology , gene
Insular oceanic islands provide excellent opportunities for the study of evolutionary processes and adaptive radiation. The Hawaiian Plantago radiation comprises six endemic taxa showing considerable inter‐ and intraspecific morphological and ecological diversity. The rDNA internal (ITS) and external (ETS) transcribed spacers and two recently described chloroplast spacers, ndhF ‐ rpl 32 and rpl 32‐ trnL , were sequenced to study phylogenetic relationships within this morphologically complex group. Phylogenetic analysis provided strong evidence for the monophyly of Hawaiian Plantago , suggesting that the lineage arose from a single long‐distance dispersal event. Inconsistencies between nuclear and chloroplast phylogenies suggest a history of hybridization. The basal, unresolved dichotomy of the combined phylogeny is consistent with rapid phenotypic diversification of the major lineages early in the history of this group. Speciation has largely occurred allopatrically, with divergence a result of intraisland ecological shifts between bog and woodland habitats and interisland dispersal events. Most interisland colonizations were from older to younger islands with initial colonization of Kaua‘i. In our analysis, P. pachyphylla is paraphyletic and taxonomic separation of the distinct morphotypes of this species appears justified. Furthermore, the apparent hybrid ancestry and unique morphology and habitat of the endangered P. princeps var. longibracteata support its recognition at the specific rank.