title: An ancient tripartite symbiosis of plants, ants and scale insects.
abstract: In the Asian tropics, a conspicuous radiation of Macaranga plants is inhabited by obligately associated Crematogaster ants tending Coccus (Coccidae) scale insects, forming a tripartite symbiosis. Recent phylogenetic studies have shown that the plants and the ants have been codiversifying over the past 16-20 million years (Myr). The prevalence of coccoids in ant-plant mutualisms suggest that they play an important role in the evolution of ant-plant symbioses. To determine whether the scale insects were involved in the evolutionary origin of the mutualism between Macaranga and Crematogaster, we constructed a cytochrome oxidase I (COI) gene phylogeny of the scale insects collected from myrmecophytic Macaranga and estimated their time of origin based on a COI molecular clock. The minimum age of the associated Coccus was estimated to be half that of the ants, at 7-9Myr, suggesting that they were latecomers in the evolutionary history of the symbiosis. Crematogaster mitochondrial DNA (mtDNA) lineages did not exhibit specificity towards Coccus mtDNA lineages, and the latter was not found to be specific towards Macaranga taxa, suggesting that patterns of associations in the scale insects are dictated by opportunity rather than by specialized adaptations to host plant traits.
authors.affiliation: Department of Mountain and Environmental Science, Interdisciplinary Graduate School of Science and Technology, Shinshu University, 3-1-1 Asahi, Matsumoto, Nagano 390-8621, Japan. s05t404@shinshu-u.ac.jp
authors.forename: Shouhei
authors.initials: S
authors.lastname: Ueda
authors.forename: Swee-Peck
authors.initials: SP
authors.lastname: Quek
authors.forename: Takao
authors.initials: T
authors.lastname: Itioka
authors.forename: Keita
authors.initials: K
authors.lastname: Inamori
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Sato
authors.forename: Kaori
authors.initials: K
authors.lastname: Murase
authors.forename: Takao
authors.initials: T
authors.lastname: Itino
mesh_terms: D000818:Animals; D001000:Ants / Q000235:genetics / Q000502:physiology*; D004272:DNA, Mitochondrial / Q000737:chemistry / Q000235:genetics; D003576:Electron Transport Complex IV / Q000737:chemistry / Q000235:genetics; D019665:Euphorbiaceae / Q000502:physiology*; D019143:Evolution, Molecular; D006430:Hemiptera / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013559:Symbiosis
chemical_list: D004272:DNA, Mitochondrial; D003576:Electron Transport Complex IV