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Abstract Detail

Evolution on Islands: a colloquium to honor the careers of Daniel Crawford and Tod Stuessy

Baldwin, Bruce [1], Wagner, Warren [2].

Examples of advances in understanding of island plant evolution from the work of Daniel Crawford, Tod Stuessy, and their collaborators.

Dan Crawford, Tod Stuessy, and their collaborators have made key insights into patterns and processes of island evolution through empirical and theoretical efforts, with research characterized by attention to exceptionally diverse lines of evidence. An example of the progress achieved by such depth of focus has been the understanding that factors that promote maintenance of genetic diversity (i.e., paleopolyploidy and genetic mechanisms that promote or enforce outcrossing) appear correlated with unusually extensive diversification in insular lineages of Compositae that are remote from their source areas. They also have underscored the striking rarity of chromosome evolution within island lineages in general, and have sought to understand that lack of change by focusing on an example of in situ polyploidization, in Tolpis (Cichorieae; Compositae). Their detailed work on disseminules of native plants of the Juan Fernandez Islands helped to solidify the case for primary importance of bird dispersal in founding of island angiosperm lineages, in line with results from other remote archipelagos, including those of the Central Pacific. There, they found that the long-enigmatic Fitchia and Operanthus (Coreopsideae; Compositae) are not only sister but also represent a particularly extreme example of long-distance dispersal from the New World. Their work was some of the earliest to show that levels of genetic variation within endemic angiosperm clades of oceanic islands were lower than in mainland relatives and that patterns of insular genetic variation are in line with timing of island emergence and, in general, with numbers and sizes of populations. The case for neo-endemism of most remote-island lineages has been advanced substantially by their findings, as has the understanding of insular paleoendemism, by their long-term studies of Lactoris (Aristolochiaceae). They also have made contributions to the understanding of hybridization in oceanic islands, with observations suggesting low incidence of modern hybridization in the flora of the Juan Fernandez Islands and strong evidence for ancient hybrid speciation there, e.g., with genetic resolution of an intergeneric hybrid origin of xMargyracaena skottsbergii (Rosaceae). The generality of their findings on island plant evolution, from studies largely centered in the Juan Fernandez Islands and Macaronesia, is evident from results of similar investigations in the Hawaiian archipelago, where our island research programs have been primarily focused.

Broader Impacts:

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1 - University Of California Berkeley, JEPSON HERB & DEPT INTEGR BIOL, 1001 Valley Life Sciences Building, MC 2465, Berkeley, CA, 94720-2465, USA
2 - Smithsonian Institution, Botany, MRC-166 National Museum Of Natural History, PO Box 37012, WASHINGTON, DC, 20013-7012, USA, 202/633-0968

adaptive radiation
genetic variation
Juan Fernandez Islands.

Presentation Type: Symposium or Colloquium Presentation
Session: C5
Location: Franklin A/Hyatt
Date: Wednesday, July 11th, 2012
Time: 9:30 AM
Number: C5005
Abstract ID:526

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