Genetic variations estimated from PCR-RFLP analysis of two morphs of the freshwater goby Rhinogobius in the Lake Biwa water system

Abstract

The freshwater goby Rhinogobius is the most abundant fish in the shore area of Lake Biwa, Japan. Recently, it has been reported that two morphs of Rhinogobius inhabit this lake. In this study, genetic variations in Rhinogobius sp. OR (Orange-type) and Rhinogobius sp. BW (Biwa-type) in the Lake Biwa water system have been investigated using polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP) analysis of mitochondrial DNA, including the variable D-loop region. Samples of Rhinogobius sp. OR were collected from the middle sites of three rivers, two outlets, and two lakeshore sites, whereas samples of Rhinogobius sp. BW were taken from two lakeshore sites. Rhinogobius sp. OR and Rhinogobius sp. BW did not share any haplotypes, suggesting that PCR-RFLP analysis is effective for distinguishing between these species of goby. The haplotype diversity of Rhinogobius sp. OR (0.214-0.543) was lower than that of Rhinogobius sp. BW (0.543-0.682). There were no significant differences in haplotype frequencies between Rhinogobius sp. BW groups from the two localities. In addition, haplotype frequencies in Rhinogobius sp. OR did not differ significantly among samples from the middle sites of rivers, the outlets, and the shores. These results indicate that in Rhinogobius sp. OR there is frequent gene flow among fish inhabiting different sites, and that this species of goby consists of a single population throughout the Lake Biwa water system.

Life‐history variation in relation to nest site abundance in males of the freshwater goby Tridentiger brevispinis

“…OR and Rhinogobius sp. BW, there are no genetic differences among populations in Lake Biwa, probably due to wide dispersal of their planktonic larvae (Takahashi & Ohara 2004). If, like these Rhinogobius species, T. brevispinis is also widely distributed along shorelines at the end of the planktonic larval period, there are unlikely to be genetic differences among populations, and the difference in age at maturity of males between the Ohmi-maiko and Minamihama populations probably results from plasticity of life-history traits.…”

Variation in behavioural response to oxygen stress by egg‐tending males of parapatric fluvial and lacustrine populations of a landlocked goby

“…In case of a genetic effect, the differential behavioural response would have evolved separately in the two populations to fit respective environments. Previous molecular analyses, however, have shown that the gene pool is shared by the two population types (Takahashi & Okazaki, 2002; Takahashi & Ohara, 2004). The extent to which this species is divergent is so limited to be virtually undetectable by molecular analyses, even if a genetic effect exists.…”

“…They have distinct spawning locations between which they can, but seldom, migrate, as shown by isotopic analysis (Maruyama et al , 2001). They both spend the larval period in the lake and molecular data suggest they share a common gene pool (Takahashi & Okazaki, 2002; Takahashi & Ohara, 2004). The fluvial population migrates upstream from the lake to the tributary rivers at the age 0+ years (Yuma et al , 2000) and spawns larger eggs in rapids or glides (Maruyama et al , 2003, 2004), where the flow maintains dissolved oxygen concentration near saturation (Allan, 1995; Hauer & Hill, 1996).…”