TY - JOUR
T1 - Evolutionary relationships and biogeography of the ant-epiphytic genus squamellaria (Rubiaceae: Psychotrieae) and their taxonomic implications
AU - Chomicki, Guillaume
AU - Renner, Susanne S.
N1 - Funding Information:
We thank Jeremy Aroles for help in the field; Two anonymous reviewers for comments on the manuscript; Bruno Corbara and Derrick Rowe for photographs; Alivereti Naikatini and Marika Tuiwawa from the University of South Pacific and the herbarium SUVA for technical support and advice; Gudrun Kadereit, University of Mainz, for the isotope-ratio mass spectrometry analyses carried out at the University of Mainz; Matthew Jebb and Sylvain Razafimandimbison for taxonomic advice, and Yannick Staedler for providing the microCT scanning images in . Yasumin S. Lermer from the Botanical Institute in Munich drew two plates (S. huxleyana and S. grayi), and Rosemary Wise from Oxford drew the S. vanuatensis plate. Curators at Dublin (DUB), Kew (K), Leiden (L), Munich (M and MSB), Oxford (FHO), Paris (P), Sydney (NSW), and SUVA provided access to relevant collections. Material from Vanuatu was collected during “SANTO 2006”, an international expedition organized by the Paris Natural History Museum, Pro-Natura International, and the Institut de Recherche pour le Développement, and sponsored by the Stavros Niarchos Foundation, the French Fonds Pacifique and the Total Foundation. The expedition operated under a permit granted to Prof. P. Bouchet by the Environment Unit of the Government of Vanuatu. This work was supported by a grant from the German Research Foundation (DFG), RE 603/20, and grants from the Society of Systematic Biologists and the American Association of Plant Taxonomy to GC.
Publisher Copyright:
© 2016 Chomicki, Renner. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
PY - 2016/3
Y1 - 2016/3
N2 - Ecological research on ant/plant symbioses in Fiji, combined with molecular phylogenetics, has brought to light four new species of Squamellaria in the subtribe Hydnophytinae of the Rubiaceae tribe Psychotrieae and revealed that four other species, previously in Hydnophytum, need to be transferred to Squamellaria. The diagnoses of the new species are based on morphological and DNA traits, with further insights from microCT scanning of flowers and leaf δ13C ratios (associated with Crassulacean acid metabolism). Our field and phylogenetic work results in a new circumscription of the genus Squamellaria, which now contains 12 species (to which we also provide a taxonomic key), not 3 as in the last revision. A clock-dated phylogeny and a model-testing biogeographic framework were used to infer the broader geographic history of rubiaceous ant plants in the Pacific, specifically the successive expansion of Squamellaria to Vanuatu, the Solomon Islands, and Fiji. The colonization of Vanuatu may have occurred from Fiji, when these islands were still in the same insular arc, while the colonization of the Solomon Islands may have occurred after the separation of this island from the Fiji/Vanuatu arc. Some of these ant-housing epiphytes must have dispersed with their specialized ants, for instance attached to floating timber. Others acquired new ant symbionts on different islands.
AB - Ecological research on ant/plant symbioses in Fiji, combined with molecular phylogenetics, has brought to light four new species of Squamellaria in the subtribe Hydnophytinae of the Rubiaceae tribe Psychotrieae and revealed that four other species, previously in Hydnophytum, need to be transferred to Squamellaria. The diagnoses of the new species are based on morphological and DNA traits, with further insights from microCT scanning of flowers and leaf δ13C ratios (associated with Crassulacean acid metabolism). Our field and phylogenetic work results in a new circumscription of the genus Squamellaria, which now contains 12 species (to which we also provide a taxonomic key), not 3 as in the last revision. A clock-dated phylogeny and a model-testing biogeographic framework were used to infer the broader geographic history of rubiaceous ant plants in the Pacific, specifically the successive expansion of Squamellaria to Vanuatu, the Solomon Islands, and Fiji. The colonization of Vanuatu may have occurred from Fiji, when these islands were still in the same insular arc, while the colonization of the Solomon Islands may have occurred after the separation of this island from the Fiji/Vanuatu arc. Some of these ant-housing epiphytes must have dispersed with their specialized ants, for instance attached to floating timber. Others acquired new ant symbionts on different islands.
UR - http://www.scopus.com/inward/record.url?scp=84977552549&partnerID=8YFLogxK
U2 - 10.1371/journal.pone.0151317
DO - 10.1371/journal.pone.0151317
M3 - Article
C2 - 27028599
AN - SCOPUS:84977552549
SN - 1932-6203
VL - 11
JO - PLoS ONE
JF - PLoS ONE
IS - 3
M1 - e0151317
ER -