Abstract
Genetic structure of the caddisfly Stenopsyche marmorata populations was studied in the Sakawa River catchment containing Miho Dam in Kanagawa Prefecture, based on the mtDNA COI region by polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) method. Primer set (product size: 160 bp) was designed based on 771 bp of mtDNA sequences from 59 individuals of S. marmorata. Five SSCP types were recognized in 330 individuals from 11 sites located in the Sakawa River and its adjacent (the Sagami River) catchments. Frequencies and diversities of the SSCP types were clearly different between the populations of upper sites of Miho dam and those of other sites (including tributary sites). This result suggests that Miho dam is a prominent barrier for the movement of S. marmorata.
