Zoological Studies

Does Variable Habitat Usage by the Japanese Eel Lead to Population Genetic Differentiation?

(2010) Freshwater habitat use by Japanese eels (Anguilla japonica) is facultative.  However, the relationship between its habitat-use strategy and the population genetic structure is still unknown.  To evaluate whether Japanese eel populations with different habitat-use behaviors display genetic differentiation, we examined the otolith Sr/Ca ratios by an electron probe microanalyzer of 166 wild Japanese eels collected from the Kaoping River of southwestern Taiwan in 2006-2007.  Eel habitat use was divided into 3 types according to the mean and standard deviation (SD) of otolith Sr/Ca ratios: type 1 (fresh water, low-migratory, the SD of the Sr/Ca ratio < 1.4‰), type 2 (brackish water, low-migratory, the SD of the Sr/Ca ratio < 1.4‰), and type 3 (highly migratory, the SD of the Sr/Ca ratio > 1.4‰).  No significant genetic differentiation was found among these 3 eel types (overall F_ST = 0.0007, p = 0.99).  Our results suggest that the diverse habitat usage by Japanese eels is due to behavioral plasticity that allows the utilization of different ecological niches, rather than a heritable character that can cause genetic differentiation among populations.