Origins of the Endemic Scaly Tree Ferns on the Galapagos and Cocos Islands
2015 (English)In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 176, no 9, 869-879 p.Article in journal (Refereed) PublishedText
Premise of research.Successful long-distance dispersal is rarely observed in scaly tree ferns (Cyatheaceae). Nevertheless, recent molecular evidence has suggested that the four endemic scaly tree ferns on the Galapagos Archipelago (Cyathea weatherbyana) and Cocos Island (Cyathea alfonsiana, Cyathea nesiotica, and Cyathea notabilis), two oceanic island groups west of Central and northern South America, probably each originated from different mainland America ancestors. However, the phylogenetic relationships inferred among these endemics and their mainland relatives have been unclear. This study is aimed at better resolving the relationships and tracing the origins of these island endemics.Methodology.Five plastid regions from 35 Cyathea species were analyzed to reconstruct phylogenetic relationships using parsimony, likelihood, and Bayesian approaches. We also estimated divergence times of these species, and our chronogram was used to reconstruct their biogeographical range history.Pivotal results.Our well-resolved phylogenetic tree of Cyathea, which is in agreement with previous studies, shows that when the four Galapagos and Cocos endemics are included, they each belong to separate subclades. Our biogeographical study suggests that the four endemics originated from independent colonization events from mainland America and that there was no dispersal of Cyathea between the island groups. We reveal more detailed relationships among the endemics and their respective close mainland relatives; some of these relationships differ from previous studies. Our findings are corroborated by new morphological data from ongoing stem anatomy studies.Conclusions.The four scaly tree ferns endemic to the Galapagos and Cocos Islands each did indeed originate as independent colonization events from separate sources in mainland America, and their closest relatives are identified here.
Place, publisher, year, edition, pages
2015. Vol. 176, no 9, 869-879 p.
Cyathea, Cyatheaceae, island biogeography, phylogenetic analysis, rbcL, rbcL-accD, rbcL-atpB, trnG-R, trnL-F
IdentifiersURN: urn:nbn:se:uu:diva-270632DOI: 10.1086/683303ISI: 000365305400006OAI: oai:DiVA.org:uu-270632DiVA: diva2:890226
FunderSwedish Research Council Formas, 2010-585