Bourgeois Males of the Peacock Blenny, Salaria pavo, Discriminate Female Mimics from Females?

Abstract

In a Portuguese population of Salaria pavo, two types of reproductively active males occur: large bourgeois males that defend nests and have fully developed secondary sex characters (SSC) and small sneaker males that mimic the femalesÕ morphology and behaviour to approach nests and parasitize fertilizations. These two alternative reproductive tactics are sequential, as sneakers develop into bourgeois males. We investigated whether bourgeois males were able to discriminate between sneakers and females of different sizes. In a laboratory experiment bourgeois males were sequentially presented with a female and a sneaker matched for size. Complementary field observations were conducted on the interactions between females and sneakers with bourgeois males. If bourgeois males discriminated females from sneakers, we predicted that they should direct more aggressive behaviours towards sneakers and more courtship acts towards females. In general, bourgeois males courted and attacked small females and sneakers equally. However, large sneakers were courted less and attacked more than large females. Larger sneakers, beginning to develop SSC, were attacked more and courted less by the bourgeois male than smaller sneakers, and larger females were attacked less and courted more than smaller females. These results strongly suggest that only small female-mimicking males were able to deceive bourgeois males. In S. pavo, if the sneakersÕ fertilization success correlates with their female-mimicking ability, a fitness decrease with an increasing body size can be predicted.

Environmental modulation of androgen levels and secondary sex characters in two populations of the peacock blenny Salaria pavo

“…Since there is no female behavioral role to imitate, parasitic males from GT cannot assume an active tactic to approach nest holders. In order to enter nests and fertilize eggs, they should either 1) rely on their female-like morphology, be courted by a nest holder and be allowed inside the nest, or 2) swiftly enter the nest while the nest holder is away and release the maximum amount of sperm in the minimum time possible (mentioned by Gonçalves et al, 2005 as a personal observation). Either way, the predictability to be in the 'right spot at the right time' to spawn should be lower and the overall variability in reproductive success in GT should be higher than at RF.…”

“…Nest holder males from RF thus have a high resource holding potential but apparently there is no pressure for sperm competition. Although there is a high prevalence of sneakers, nest holders do not easily discriminate them from females (Gonçalves et al, 2005) and so their perception of reproductive competitors is reduced. This set of data suggests that there is a threshold size for males to breed as nest holders in RF, and once achieved the reproductive success is high and apparently guaranteed.…”

Intra-sexual variation in male reproduction in teleost fish: a comparative approach

“…The choice to reproduce or not in their first breeding season is likely to depend on body size as the efficiency of female mimicry may decrease as body size increases (Oliveira et al, 2001f). In fact, although sneakers are on average good female mimics to the eyes of nest-holders, sneakers receive more attacks and less courtship displays from nesting males as their body size increases (Gonçalves et al, 2005). In an ongoing mark-recapture study started in 2000 (with over 500 individuals marked so far), all sneakers and immature males marked in a given breeding season and recaptured in the following year had developed secondary sexual characters and many successfully defended a nest with eggs (T. Fagundes, D. Gonçalves, and R.F.…”

Editorial Note on Reproductive Biology of Fishes

“…The compilation of such information, based on new data but including a review of relevant studies, will justify a stand-alone publication for a single species. Exceptional behavioural patterns or tactics (e.g., bourgeois and parasitic sperm competing males: Taborsky 1998, Gonçalves et al 2005 and diversions from the norm (e.g., unexpected reproductive strategy: Freon et al 1997) may need more research and discussion and justify also a research article. Ichthyoplankton surveys also provide important information on the spawning of fishes, such as defining the extent of the spawning period (e.g., Tsikliras et al 2010), but are not considered here as they belong to a scientific field of their own.…”