J Syst Evol ›› 2018, Vol. 56 ›› Issue (6): 621-636.DOI: 10.1111/jse.12454

• Research Articles • Previous Articles     Next Articles

The odd one out or a hidden generalist: Hawaiian Melicope (Rutaceae) do not share traits associated with successful island colonization

Claudia Paetzold1*, Michael Kiehn2,3, Kenneth R. Wood3, Warren L. Wagner4, and Marc S. Appelhans1,4   

  1. 1Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium), Goettingen University, Untere Karspuele 2, Goettingen, D-37073, Germany
    2Core Facility Botanical Garden, University of Vienna, Rennweg 14, A-1030, Austria
    3National Tropical Botanical Garden, 3530 Papalina Road, Kalaheo, HI 96741, USA
    4Department of Botany, National Museum of Natural History, Smithsonian Institution, P.O. Box 37012, MRC 166, Washington, DC 20013-7012, USA
  • Received:2018-02-14 Accepted:2018-07-16 Online:2018-08-30 Published:2018-12-13

Abstract: Oceanic islands are unique in their species composition, which is defined by arrival of colonizers via long distance dispersal followed by establishment of species followed in some cases by adaptive radiation. Evolutionary biologists identified traits facilitating successful colonization of islands as including polyploidy, self‐compatibility, herbaceousness and ability for long‐distance dispersal. Successful establishment and evolutionary diversification of lineages on islands often involves shifts to woodiness and shifts in methods of outcrossing as well as changes in dispersal ability. The genus Melicope colonized numerous archipelagos throughout the Pacific including the Hawaiian Islands, where the lineage comprises currently 54 endemic species and represents the largest radiation of woody plants on the islands. The wide distributional range of the genus illustrates its high dispersibility, most likely due to adaption to bird dispersal. Here we investigate ploidy in the genus using flow cytometry and chromosome counting. We find the genus to be paleopolyploid with 2n = 4x = 36, a ploidy level characterizing the entire subfamily Amyridoideae and dating back to at least the Palaeocene. Therefore Hawaiian Melicope have not undergone recent polyploidization prior to colonization of the islands. Thus Melicope retained colonization success while exhibiting a combination of traits that typically characterize well established island specialists while lacking some traits associated to successful colonizers.

Key words: bird dispersal, colonization, establishment, long distance dispersal, Pacific, polyploidy