Abstract
There is growing awareness of the need to evaluate the long-term effects of wildlife populations, not only in terms of the level of short-term effects on individuals, but also in terms of much subtler, multigenerational effects particularly for long-term conservation of ecosystems. Here, we show population genetic structure of Pseudorasbora parva in the Kanto region and estimate the main stressors to influencing genetic variability and genotype. Genetic diversity within a population was significant among sampling sites, but no significant relationship was detected between genetic diversity and contaminants, such as polycyclic aromatic hydrocarbons (PAHs) and heavy metals, because of many types of stress effects and random genetic drift. On the other hand, cluster analysis of the fluorescence intensity of individual DNA fragment profiles measured by amplified fragment length polymorphism (AFLP) analysis identified five genotypes: two existed in many sites in the Kanto region, and three existed in only a few sites. Genetic diversity or genotype proportion in a population at the sites where these two genotypes was dominant were also significantly related to dissolved PAH, dissolved fluoranthene, dissolved benzo[k]fluoranthene and benzo[k]fluoranthene concentrations in sediments. Finally, the population genetic structure in eight sites along the Nogawa river was evaluated. These results showed genetic diversity and genotype proportion changed discontinuously in some sites, because of changes in PAH concentration and limited migration.
