In a close parallel to the human world, lonely male desert gobies (Chlamydogobius eremius) are desperate males, according to a study published in the most recent issue of the journal Behavioral Ecology and Sociobiology.
The male desert goby undertakes elaborate courtship displays to attract females, but the displays come at a price — significant time, energy and exposure to predation is expended.
Conventional theory thus predicts that males should adjust their signaling efforts to court only high-quality females (usually meaning the largest females, as these are likely to bear the most eggs) and that this adjustment depends on the rate at which they encounter females.
Given that this theory has rarely been experimentally tested, Andreas Svensson, Topi Lehtonen and Bob Wong of Monash University carried out a study investigating the effects of female encounter rate on male courtship intensity by manipulating the time interval between sequential presentations of large (high quality) and small (low quality) females using the desert goby as an experimental subject.
The authors sequentially exposed a large and a small female goby to males in test aquaria, differing treatments by the interval at which the females were introduced: in the short interval treatment, the small female was introduced after 11 minutes on average while in the long treatment, the small female was introduced after 24 hours on average.
They also re-analysed data from a previous experiment in which the males were presented females as in the short interval treatment, but in a reversed order (i.e. small female followed by large female). The authors then recorded the behaviour of the male every 10 seconds over a 10-minute observation period, scoring for the number of times the males associated with and displayed to the females.
The results of the study showed that the males dramatically reduced both association time and courtship intensity when they were presented with a small female shortly after encountering a large female, whereas they courted both large and small females with equal zeal when the time interval between presentations was much longer.
The study therefore suggests that the male desert goby can adjust its courtship tactic based on the rate at which it encounters females.
According to Bob Wong: "These findings are important because, for a long time, females were typically regarded as the more discerning sex when it comes to choosing a potential mate. Here, we show that males, too, can be highly picky and are much more tactical in whom they choose to court."
For more information, see the paper: Svensson, PA, TK Lehtonen and BBM Wong (2010) The interval between sexual encounters affects male courtship tactics in a desert-dwelling fish. Behavioral Ecology and Sociobiology 64, pp. 1967–1970.