Simultaneous production of triploid and haploid eggs by triploid Squalius alburnoides (Teleostei: Cyprinidae)

Abstract

The hybrid minnow Squalius alburnoides comprises diploid and polyploid forms with altered modes of reproduction. In the present paper, we report a cross where a triploid female generated both large, triploid and small, haploid eggs simultaneously, which were fertilized with S. pyrenaicus sperm. Although the large eggs were rarer (15%), they originated offspring with higher survivorship, so that tetraploids were dominant among the surviving siblings. The cross yielded apparently all female progeny. Inheritance patterns were inferred using four microsatellite markers and NORs (Nucleolus Organizer Regions) phenotypes, and suggested that haploid eggs were probably produced by an atypical hybridogenesis, in which the elimination of the unmatched genome permitted random segregation and recombination between the homospecific genomes, while the triploid eggs were clonal. The present results suggest that the occurrence of triploid unreduced eggs may be a new route for the natural tetraploidization in the complex.

Disruption of normal meiosis in artificial inter-populational hybrid females of Misgurnus loach

“…The simultaneous appearance of various ploidy-types of eggs has been reported in natural triploids and diploid-triploid mosaics, accidentally derived from a natural clonal lineage of the loach (Oshima et al, 2005;Yoshikawa et al, 2007). Similar observations of simultaneous formation of different types of eggs were reported in triploid (diploid x tetraploid) loach (Matsubara et al 1995;Arai andMukaino, 1997, 1998;Momotani et al, 2002), spontaneous triploid in central area of Honshu Island, Japan (Zhang and Arai, 1999) and other triploid teleosts including minnow in the genus Squalius (Alves et al, 2004) and Phoxinus (Dawley and Goddard, 1988;Goddard and Dawley, 1990).…”

Reproductive success of nuclear nonhybrid males of Squalius alburnoides hybridogenetic complex (Teleostei, Cyprinidae): an example of interplay between female choice and ecological pressures?

“…It is important to stress that both male and female diploid PA hybrids (the form that probably was at the origin of the complex) do not undergo meiosis, producing gametes clonally (reviewed in Alves et al 2001). Most triploids are PAA females that reproduce by meiotic hybridogenesis once they exclude the P genome, after which the AA genomes undergo meiosis and recombination, generating haploid A gametes, although they can produce other gametes, namely, AA and even PAA eggs (Alves et al 2004).…”

A novel allotetraploid gibel carp strain with maternal body type and growth superiority

“…Additionally, the whole genome incorporation and chromosome incorporation were also observed in some other gynogenetic fishes including unisexual Poeciliopsis (Quattro et al, 1992), Poecilia formosa (Schartl et al, 1995), and Squalius alburnoides (Alves et al, 2001(Alves et al, , 2004Pala and Coelho, 2005). The resulted allopolyploid hybrids were thought to not only have significantly ecological implications for population differentiation and even speciation, but also to be an efficient approach for selective breeding (Gui and Zhu, 2012).…”