Morphology, testes development and behaviour of unusual triploid males in microchromosome‐carrying clones of Poecilia formosa

Abstract

In a microchromosome-carrying laboratory stock of the normally all-female Amazon molly Poecilia formosa triploid individuals were obtained, all of which spontaneously developed into males. A comparison of morphology of the external and internal insemination apparatus and the gonads, sperm ploidy and behaviour, to laboratory-bred F 1 hybrids revealed that the triploid P. formosa males, though producing mostly aneuploid sperm, are partly functional males that differ mainly in sperm maturation and sexual motivation from gonochoristic P. formosa males.

Extra Microchromosomes Play Male Determination Role in Polyploid Gibel Carp

“…In Chilomycterus spinosus (Noleto et al 2012) and one clone of P. formosa (Lamatsch et al 2000;Lamatsch et al 2010), they were revealed to be associated with male determination; whereas in Sphoeroides spengleri, they were found to be related to female determination (Noleto et al 2012). Intriguingly, the extra microchromosomes in male gibel carp are dispensable for a normal life cycle, and their number and morphology varies between individuals (Figure 2 and Figure S1).…”

High male incidence and evolutionary implications of triploid form in northeast Asia Carassius auratus complex

“…In past, occasional or rare males were reported in other unisexual teleosts including Poecilia Formosa (Hubbs et al, 1959;Lamatsch et al, 2010;Schlupp et al, 1992), Squalius alburnoides (Alves et al, 1999;Sousa-Santos et al, 2007), Phoxinus eos-neogaeus (Goddard and Dawley, 1990), Cobitis sp. (Vasil'ev et al, 2003), Misgurnus anguillicaudatus (Itono et al, 2006), and their fertile function was revealed in unisexual Squalius alburnoides (Sousa-Santos et al, 2007) and Poecilia formosa (Lamatsch et al, 2010). In the triploid form of Carassius auratus complex, approximate 1-10% of triploid males were sporadically reported in natural habitats (Gui and Zhou, 2010), but the unusually triploid male incidence of high up to 23% should be firstly discovered in the gynogenetic triploid form.…”

Gene copy silencing and DNA methylation in natural and artificially produced allopolyploid fish

“…/, to be read as 'either or'; (), presence or absence of the allele not unequivocally determined; _, allele expression pattern not assessed. P. formosa individuals may be the consequence of differential contribution of genomes to overall expression (Lamatsch et al, 2010(Lamatsch et al, , 2011. The failure then to detect AS also in the naturally occurring triploid of the mml genomic constitution was somehow unexpected as the naturally occurring triploid P. formosa were proposed earlier as good candidates where a comparable gene-copy silencing phenomenon like in S. alburnoides could occur (Pala et al, 2008).…”

“…Therefore, we consider them as naturally occurring 'old triploids'. We also analyzed TGH P. formosa triploids of mlb and mls genomic composition that were experimentally produced through specific crosses between Poecilia strains and species Lamatsch et al, 2010). We can consider these individuals as 'de novo' allotriploids, as increases in both ploidy and hybridity happen at the moment of production of each of these TGH individuals.…”

“…On the contrary, triploids that are obtained de novo from diploid P. formosa as rare introgression cases in laboratory broods (Nanda et al, 1995) do not give rise to stable gynogenetic lines. These de novo triploids comprise different genomotypes depending on the parental species used for breeding, including tri-genomic hybrids (TGHs) with mls (P. formosa, ml, with introgressed genome from P. salvatoris, s) or mlb (P. formosa, ml, with introgressed genome from black molly, b) genomic composition (Lamatsch et al, 2010) (Fig. S2C).…”