Genetic features of Tachypleus tridentatus in Japan and an alien (non-native) population founded at Ise-Mikawa Bay, Chubu Region, Central Japan

Abstract

The tri-spine horseshoe crab Tachypleus tridentatus, known as a living fossil and endangered, is distributed from coastal Southeast Asia to western Japan. The Japanese population represents the northernmost range for this species. To examine the genetic structure and diversity of the Japanese population, over 600 samples from ten localities were analyzed using mitochondrial DNA AT-rich region sequences as a maternal inheritance marker and over 250 samples using nucleic compound microsatellite loci as biparental markers. Genetic subdivisions were detected in Japanese populations using both markers. Two genetically distinct groups, the western and the eastern group, were detected and six tentative local management units were defined. Locality and genetic units should be taken into account for conservation of Japanese populations. Furthermore, we report on an alien (non-native) population founded in Japan. Sixty-two individuals including 13 adults were captured in 12 years (from 2001) from Ise-Mikawa Bay, which is out of range of their natural habitat. Genetic analysis and other information indicated that the origin of these individuals was mainland China. This indicates the possibility that even an endangered species can become an alien and invasive one.