Controlled breeding studies to verify the identity of roach and common bream hybrids from a natural population

Abstract

The occurrence of post-F1 generation hybrids between common bream and roach in natural populations has still to be qualified. To do this, common bream, roach, F1 and F2 hybrid progeny were produced under controlled conditions. All progeny groups exhibited overlaps in the ranges of their meristic characters. Discriminant analysis of meristic data combined with allozymes allowed identification of post-F1 hybrids. Enzyme electrophoresis showed F1 progeny to be heterozygous at diagnostic loci. Back-crossed F2 progeny had a mixture of homozygosity and heterozygosity at diagnostic loci. Meristic and genetic analysis of fish from a natural population indicated that they were all F1 hybrids. Post-F1 hybridization cannot be ruled out from natural populations because F1 hybrids are known to be fertile. It is suggested that post-F1 hybrids were not detected either because of their low incidence of occurrence or due to biological phenomenon such as inferior fitness. 1997 The Fisheries Society of the British Isles 1997 The Fisheries Society of the British Isles

Hybridisation between two cyprinid fishes in a novel habitat: genetics, morphology and life-history traits

“…A similar selective pressure may be operating on some back-crossed progeny. Previous studies have demonstrated that the progeny of back-crosses tend to have a morphology intermediate between the parent species and the F1 hybrid [26,31]. Morphometric analysis in the present investigation, though confirming the presence of such fish in both Lough Ramor and Ross Lake, did not reveal the existence of significant numbers of intermediate morphologies (Fig.…”

Biochemical assessment of evolution and taxonomy of the morphologically poorly diverged geckos, Gekko yakuensis and G. hokouensis (Reptilia: Squamata) in Japan, with special reference to their occasional hybridization

“…Natural hybridization has been well documented, but in few cases does it lead to an introgression between the species involved. This is because hybrids usually have low fertility and/or viability (Dowling & Moore, 1985;Hewitt, 1989;Green & F'ustowaka, 1997;Pitts et al, 1997). It is thus worth analysing the genetic structure of the present hybrid populations in more detail to see whether frequencies of the post-F1 individuals meet assumptions of random mating and equivalent survivorship among genotypes.…”

Identification of cyprinid hybrids by using geometric morphometrics and microsatellites

“…Interspecific and intergeneric hybridization has been reported within the family Cyprinidae (Briolay et al., 1998). Ten different cyprinid hybrids have been reported from the British Isles (Wheeler, 1969) and Europe (Ross and Cavender, 1981; Pitts et al., 1997; Hänfling et al., 2005; Wyatt et al., 2006). Species of the sub‐family Leuciscinae seem to hybridize more frequently than other cyprinid species, with hybrids of common bream Abramis brama (L.) and roach Rutilus rutilus (L.) representing the most common hybrid fish in waters of the British Isles (Pitts et al., 1997).…”

“…Wheeler (1969) describes hybrids as resembling white bream, whereas Swinney and Coles (1982) point out that hybrids are more similar to common bream. However, nuclear markers have proven to be an effective tool for the differentiation of cyprinid species and the detection of interspecific hybrids (Pitts et al., 1997; Freyhof et al., 2005; Hänfling et al., 2005). Additionally, analysis of mitochondrial DNA allows the identification of the maternal species and gives information about the direction of hybridization.…”