Population Genetic Structure among Intra-Annual Arrival Waves of the Japanese Eel Anguilla japonica in Northern Taiwan

structure among intra-annual arrival waves of the Japanese eel Anguilla japonica in northern Taiwan. Zoological Studies 46(5): xxx-xxx. A previous study showed that the Japanese eel Anguilla japonica Temminck & Schlegel is not a panmictic species, as it is divided into low- and high-latitude groups, but it shows no significant genetic differentiation among year cohorts in the same habitat. However, based on hatching dates back-calculated from otolith of elvers recruited in Taiwan in the winter, the arrival waves of elvers are from different intra-annual cohorts with separate spawning times. To test if temporal genetic differentiation exists within intra-annual cohorts, 7 polymorphic microsatellite DNA loci were examined. Four arrival waves of Japanese eel elvers were collected from a single location in northern Taiwan from Nov. 2000 to Mar. 2001. Deviations from Hardy-Weinberg equilibrium were found in three of the 7 loci after the Bonferroni correction, and five of the 7 loci were used for a genetic variation test. No significant genetic differentiation was observed among the overall sample (FST = 0.0029, p = 0.173), and subtle, but significant, differentiation was only found between temporal cohorts of November and Decembe