Genetic structures of allopatric and sympatric populations in Pseudorasbora pumila pumila and Pseudorasbora parva

Abstract

Pseudorasbora pumila pumila was collected to investigate its genetic relationships from 11 localities in Hokkaido and eastern Honshu of Japan with Pseudorasbora parva from 6 localities in Hokkaido, eastern Honshu, and Polovynka River (a tributary of the Amur River in eastern Russia) in 1996-1998. In Hokkaido and Akita prefectures (Honshu), three P. pumila pumila populations were distributed with P. parva sympatrically. Samples of P. pumila pumila and P. parva were analyzed based on 27 allozyme loci. Genetic differentiation between P. pumila pumila and P. parva (D = 0.522-0.622, average 0.601) was almost equal to or greater than that between other congeneric fish species previously reported. In the three sympatric populations of two species, which had arisen from artificial transplantation of the latter into localities of the former, the individual frequency composition of genetic types (P. pumila pumila, P. parva, F 1 hybrid, and later filial generation hybrid) were significantly different from each other. Differing from the previous studies, F 1 hybrids were fertile and coexisting populations of the two species included the F 1 hybrid and the later filial generation hybrid. These results suggest that genetic population dynamics of sympatric populations of the two species would be influenced not only by hybridization but also by ecological and environmental factors. Alternatively, the existence of populations that possessed both the alleles specific to P. pumila pumila and those specific to P. parva may indicate that introgressive hybridization, instead of species displacement, has occurred between the two species under a certain condition.

Pan‐continental invasion of Pseudorasbora parva: towards a better understanding of freshwater fish invasions

“…This has been noted to occur between P. parva and P. pumila (an endangered freshwater minnow native to inland waters of Japan), resulting in the extirpation of P. pumila in some areas where P. parva has been accidentally introduced (Konishi et al. 2003; Koga and Goto 2005). Although male reproductive success in both species is determined by body size, P. parva grow faster and larger, resulting in both asymmetric inter‐specific mating between P. parva males and P. pumila females, resulting in the subsequent displacement of P. pumila (Konishi and Takata 2004).…”

Identifying conservation priority ponds of an endangered minnow, Pseudorasbora pumila, in the area invaded by Pseudorasbora parva

“…Currently, P. pumila is ranked as endangered (EN) by the Ministry of the Environment of Japan (2003). Previous genetic analyses revealed low genetic diversity in P. pumila populations, suggesting the deleterious effects of habitat fragmentation and loss (Konishi et al 2003;Koga and Goto 2005). Modernization and abandonment of traditional agricultural practices in Japan might further decrease habitats suitable for P. pumila, necessitating the evaluation of habitat requirements to manage the present populations.…”

“…Another factor frequently implicated in the decline of P. pumila is the species replacement of P. pumila by the congener Pseudorasbora parva (Japanese name, Motsugo) following hybridization (Hosoya 1979;Uchiyama 1987;Konishi et al 2003;Konishi and Takata 2004;Koga and Goto 2005). Pseudorasbora parva is distributed throughout almost all of eastern Asia, including western Honshu (Nakamura 1969).…”