Abstract Detail



Pacific Biogeography

Baldwin, Bruce [1], Wood, Kenneth R. [2], Freyman, William [3].

Revisiting cytonuclear discordance, habitat shifts, and biogeographic patterns in the Hawaiian silversword alliance (Compositae).

Expanded phylogenetic analyses of the endemic Hawaiian silversword alliance (Argyroxiphium, Dubautia, Wilkesia; Compositae–Madiinae) provide evidence for more ancient habitat shifts, hybridization events, and clade structure — including a previously unresolved major clade — than were identified in earlier studies of this prominent example of adaptive radiation.  Up to 235 samples spanning the within- and between-island geographic and ecological distributions of all 45 recognized taxa were included in maximum likelihood and Bayesian inference analyses of nuclear ribosomal DNA ETS+ITS (nrDNA) and chloroplast DNA (cpDNA) sequences.  Resulting trees indicate that phylogenetic incongruence detected previously appears to reflect extensive chloroplast capture, as earlier suspected.  For example, DNA sequences representing different populations of the same species or subspecies recognized by Carr and colleagues (based primarily on morphology and cytology) almost always belong to the same minimal well-supported clade based on nrDNA but not cpDNA.  Conspecific cpDNA sequences were sometimes separated across the deepest resolved nodes in the plastome trees.  Ecological shifts between highly contrasting habitats, shown earlier to have occurred on each major island or island group during diversification of the silversword alliance, extend to bog situations.  Multiple independent evolutionary shifts to bog habitat may help to explain stable sympatry of four fully to partially interfertile taxa of Dubautia in the summit bog of Wai`ale`ale on Kaua`i.  A phylogenomic study of tribe Madieae using target-enriched nuclear loci is underway to bring additional resolution to the origin and adaptive radiation of the silversword alliance.


1 - University Of California, Jepson Herbarium & Dept. Of Integrative Biology, 1001 Valley Life Sciences Bldg. #2465, Berkeley, CA, 94720, United States
2 - National Tropical Botanical Garden, 3530 Papalina Road, Kalaheo, HI, 96741, USA
3 - University of California, Jepson Herbarium & Dept. of Integrative Biology, 1001 Valley Life Sciences Bldg. #2465, Berkeley, CA, 94720, United States

Keywords:
adaptive radiation
Argyroxiphium
Asteraceae
biogeography
bogs
Compositae
Dubautia
habitat shifts
Hawaii
hybridization
islands
Madiinae
Pacific
silversword alliance
Wilkesia.

Presentation Type: Colloquium Presentations
Number:
Abstract ID:879
Candidate for Awards:None


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