Aspects of the mating behaviour of male mollies (Poecilia spp.)

Abstract

The unisexual fish Poecilia formosa (the Amazon molly) reproduces by gynogenesis, a process in which sperm from the males of the host bisexual species activates development of its eggs. Unisexuals live with one of the host species in nature and compete with bisexual females for the males. It was long thought that male discrimination and mate selection established a balance between the unisexual and bisexual populations. Thus, hierarchies of males were set up in which dominant males mated with their conspecific females and subordinates mated with the Amazon molly. Recent evidence suggested, however, that male fish do not discriminate between their own females and the Amazon molly, and that there always are more males available than sexually receptive females of both species.Our findings indicate that male behaviour may be more complex than suggested by either hypothesis. Mate discrimination and courtship behaviour appear to increase with age, so that large males show almost complete preference for their conspecific females, but smaller males will mate with the Amazon molly. In complex groups, small males often dart in and mate with their own females whilst the large males are engaged in courtship activities and defence of territory.

Peering Through the Looking Glass at a Sexual Parasite: Are Amazon Mollies Red Queens?

“…Poecilia mexicana male discrimination may be affected by the order in which they encounter various females, particularly if males are highly motivated to mate. There may also be considerable plasticity in discrimination of individual males and/or polymorphism in the population (Woodhead and Armstrong 1985;Balsano et al 1985). Of course, all of these possibilities are speculative without additional data.…”

“…These females exploit males of the closely related species P. latipinna, the sailfin molly (Breden et al 1999), and P. mexicana, the Atlantic molly, for sperm (Hubbs and Hubbs 1932;Hubbs 1964;Balsano et al 1981Balsano et al , 1985Schartl et al 1995a). This species complex has been studied extensively in an attempt to understand the evolution of mate discrimination, and its role in the persistence of P. formosa, because the agents and targets of selection are easy to identify (Hubbs 1964;Woodhead and Armstrong 1985;Schlupp et al 1991Schlupp et al , 1994Foran and Ryan 1994;Ryan et al 1996;Schlupp and Ryan 1996;Ptacek and Travis 1997;Witte and Ryan 1998;Kö rner et al 1999;Landmann et al 1999;Gabor and Ryan 2001;Niemeitz et al 2002;Schlupp et al 2002).…”

Male Mate Choice in Mixed Bisexual/Unisexual Breeding Complexes of Poecilia (Teleostei: Poeciliidae)

“…latipinna complex the situation seems to be different. HUBBS (1964), WOODHEAD & ARMSTRONG (1985) and RYAN (unpubl. ) found male preference for conspecific females in sympatric as weH as in aHopatric populations and in laboratory stocks.…”

“…It seems reasonable to assurne a selection pressure, that forces males to discriminate conspecific (P. latipinna or P. mexicana) and parasitic (P. formosa) females (KAWECKI 1988). Male choice has been demonstrated in the P. formosal P. latipinna complex (HUBBS 1964;WOODHEAD & ARMSTRONG 1985) but seemed to be absent in the P. formosalP. mexicana complex (BALSANO et al 1981complex (BALSANO et al , 1985.…”

The effect of ontogenetic experience on variation in growth, maturation, and sexual behavior in the sailfin molly,Poecilia latipinna (Pisces: Poeciliidae)

“…Males exhibit negligible growth after reaching maturity (Snelson 1982(Snelson ,1984, and in poeciliid fishes in general, female growth rates decrease after maturity. Male sexual behavior is size dependent: larger males within populations exhibit relatively high levels of courtship, and smaller males court little but exhibit high levels of forced insemination attempts (Parzefall 1969, Luckner 1979, Woodhead & Armstrong 1985. Large males are able to defeat smaller ones in agonistic interaction (Baird 1968, a factor especially important because females with fertilizable ova are recognized by males and are active centers of intermale competition (Parzefalll973, .…”