Genetic Analysis of Population Structure of Coptotermes gestroi (Isoptera: Rhinotermitidae) in Native and Introduced Populations

Weusedmicrosatellitemarkers to characterize the population structure ofCoptotermes gestroi (Wasmann), an economically important termite species in the tropics. Eighty-Þve colonies were sampled from seven countries (Malaysia, Thailand, Singapore, Indonesia, the Philippines, Taiwan, and the United States [Hawaii]). Ten to 20 workers per colony were genotyped using eight variable microsatellite loci. STRUCTURE analysis partitioned the 13 spatially separated populations into four clusters. Individuals in the Peninsular Malaysia and Singapore population groups displayed admixtureclusters.Therewas lowgeneticdifferentiation(FST 0.073)among thePeninsularMalaysia populations, suggestingmoderate gene ßow among them. Comparatively, therewasmoderate genetic differentiation (FST 0.192) and positive correlation between genetic distance and geographic distance among all of the 13 putative populations studied, which suggests limited gene ßow among them. There was no signiÞcant isolation by distance within the three largest populations (Penang, Kuala Lumpur, and Singapore), presumably because humans aid the dispersal and fragmentation of colonies in these cities.However, signiÞcant isolationbydistancewas found in introducedpopulations (Taiwan).Population structure analysis demonstrated thatC. gestroipopulations inTaiwanwere likely introduced from the Philippines.