In the Southeast Asian tropics, Arhopala lycaenid butterflies feed on Macaranga ant-plants inhabited by Crematogaster (subgenus Decacrema) ants tending Coccus-scale insects. A recent phylogenetic study showed that (1) the plants and ants have been codiversifying for the past 20-16 million years (Myr), and that (2) the tripartite symbiosis was formed 9-7 Myr ago, when the scale insects became involved in the plant-ant mutualism. To determine when the lycaenids first parasitized the Macaranga tripartite symbiosis, we constructed a molecular phylogeny of the lycaenids that feed on Macaranga by using mitochondrial and nuclear DNA sequence data and estimated their divergence times based on the cytochrome oxidase I molecular clock. The minimum age of the lycaenids was estimated by the time-calibrated phylogeny to be 2.05 Myr, about one-tenth the age of the plant-ant association, suggesting that the lycaenids are latecomers that associated themselves with the pre-existing symbiosis of plant, ant, and scale insects.ArticleECOLOGICAL RESEARCH. 27(2):437-443 (2012)journal articl
