Microsatellite variation reveals fine‐scale genetic structure of masu salmon, Oncorhynchus masou, within the Atsuta River

Abstract

To describe in detail the population genetic structure of masu salmon Oncorhynchus masou, seven anadromous populations in the Atsuta River were investigated by analysis of eight polymorphic microsatellite loci. Exact test and genetic differentiation (F ST ) revealed that significant differentiation was observed at the within-river scale. Principal components analysis revealed that the spatial pattern of genetic composition was related to geographical location of each population. Furthermore, a significant correlation was observed between genetic differentiation and geographical distance, indicating that dispersal is less likely to occur between distant populations. The results of this study imply that masu salmon have potential to show clear genetic structure at the microgeographical scale (21 km) due to precise homing behaviour.

Influences of habitat fragmentation by damming on the genetic structure of masu salmon populations in Hokkaido, Japan

“…In the below-dam region, although the levels of genetic differentiation estimated by F ST were week, significant genetic differentiation and IBD were observed, implying that gene flow may be more likely to occur between neighboring populations (Primmer et al 2006). These results are concordant with previous studies, which demonstrated that masu salmon have the potential to show genetic structuring at the local scale due to their homing behavior (the Atsuta River, sea of Japan side of Hokkaido; Kitanishi et al 2009). In contrast to the below-dam region, no evidence of IBD was revealed above the dam, despite the significant genetic differentiation within this area.…”

“…No case of LD was detected systematically for the same pair of loci across different populations. In addition, some loci showed no evidence of LD in a previous study (Kitanishi et al 2009). Therefore, we used the entire suite of 10 microsatellite loci and treated them as being independent.…”

“…Kitanishi unpublished data). A recent study reported that masu salmon in an undammed river exhibited fine-scale genetic structuring owing to relatively strong natal homing (Kitanishi et al 2009), suggesting that masu salmon showing population genetic structuring within an above-dam region would be ideal for investigating the influences of damming on genetic structuring.…”

“…Given that habitat size may reflect population size, a greater water level in the above-dam region could mitigate some of the negative impacts caused by damming. In addition, several studies have reported that salmonid species can exhibit fine-scale genetic structuring (e.g., Primmer et al 2006;Neville et al 2007;Kitanishi et al 2009), indicating that genetic structuring could occur even within the above-dam region. Therefore, investigations using large numbers of population samples per dam and comparisons of detailed genetic structuring between samples collected from both sides of the dam are required for a detailed understanding of the effects of habitat fragmentation on genetic structuring.…”

Spawning site selection and the influence of incubation environment on larval success in interior Fraser coho.

“…Quinn et al (2006) present evidence of very fine scale homing in sockeye salmon. Genetic evidence has shown that masu salmon (Oncorhynchus masou) have clear genetic structure at the microgeographical scale (21 km) due to precise homing behaviour (Kitanishi et al, 2009). …”