Testes size and breeding systems in Japanese annrans with special reference to large testes in the treefrog, Rhacophorus arboreus (Amphibia : Rhacophoridae)

Abstract

Testes size was compared among 19 species of Japanese anurans in relation to their breeding systems. Although the mean body mass of the species examined varied markedly between 1.8 and 116 g, the mean proportion of testes mass to body mass was fairly constant at 0.2 to 0.4% across all species except the rhacophorid species. Foam-nest building rhacophorids had relatively large testes constituting more than 1% of their body mass. Among them, Rhacophorus arboreus had the largest, exceeding 5% of the body mass. Multi-male breeding, where a female is grasped by two or more males during spawning, occurs frequently in these rhacophorids, especially in R. arboreus. This close association between large testes size and multi-male breeding strongly suggests that sperm competition is an important factor affecting the evolution of relative testes size in Japanese anurans.

Altitude underlies variation in the mating system, somatic condition, and investment in reproductive traits in male Asian grass frogs (Fejervarya limnocharis)

“…Second, relatively large testes are often interpreted as an adaptation to a higher risk of sperm competition (e.g., Kusano et al 1991;Byrne et al 2002), which in frogs can result from various forms of simultaneous polyandry (Roberts and Byrne 2011). For F. limnocharis, we currently lack conclusive reports on the mating system, but our repeated observation of satellite males near calling territorial males suggests that there is potential for simultaneous polyandry in this species (Roberts and Byrne 2011).…”

Latitudinal variation in testis size in six species of North American songbirds

“…Increasingly, a great deal of attention has been focused on the way in which sperm competition affects behaviour, ecology, and morphology (Birkhead 1988;Westneat et al 1990;Wagner 1992;Birkhead et al 1993). Testis size and its relation to sperm competition (Short 1979;Harcourt et al 1981;Birkhead and Møller 1992;Hosken 1997), mating system (Kenagy and Trombulak 1986;Kusano et al 1991;Briskie 1992Briskie , 1993Rising 1996;Kappeler 1997), extrapair paternity (Mulder and Cockburn 1993;Moller and Briskie 1995), asymmetry (Møller 1994;Kimball et al 1997), and body size (Cartar 1985;Kenagy and Trombulak 1986;Olsen 1991;Dahl et al 1993;Rising 1996) have been thoroughly examined. However, little is known about geographic variation in testis size (see Rising 1987).…”

Using testis size to predict the mating systems of New Zealand geckos

“…1981;Möller 1989;Heske & Ostfeld 1990), birds (Möller 1988(Möller ,1991, amphibians (Kusano et al 1991;Emerson 1997) and reptiles (Olsson & Madsen 1998). Although this variation may be explained partly by differing hormonal requirements (Moreira et al 1997), large variation in relative testis size has also been found in invertebrates (Gage 1994), in which the testes do not function in hormone production (Gillott 1980).…”

“…However, a number of studies have shown that the degree of promiscuity inmating behaviour is the strongest predictor of relative testis size across taxa (Short 1979;Harcourt et al 1981;Kusano et al 1991;Moller 1991;Gage 1994;Harcourt et al 1995;Stockley et al 1997), with highly promiscuous species exhibiting larger relative testis sizes than more monogamous species, so that relative testis size has been used as a reliable predictor of mating system (Harcourt et al 1995).…”