![]() The average flight cost measured using the bicarbonate technique was 2.24☐.11 W (mean±SE). ![]() The energy expenditure (watts) during flight was calculated from these values using the average RQ measured during flight of 0.79. Breath samples, collected before and after flight, were used to calculate k c over the flight period, which was converted to VO 2 and VCO 2 using the equation generated in the validation experiment for the corresponding time period. A second group of birds ( n=11) were flown for 2 min (three times in ten birds and twice in one) between 15 min and 20 min following an injection of 0.2 ml of the same NaH 13CO 3 solution. Adding the bicarbonate pool size (N c) into the prediction did not improve the fit. Elimination rates measured 15–20 min after injection gave the closest relationships to VO 2 ( r 2 =0.82) and VCO 2 ( r 2=0.63). The elimination rate (k c) of the 13C isotope in breath was compared to VO 2 (ml O 2/min) and VCO 2 (ml CO 2/min) over sequential 5-min time intervals following administration of the isotope. Isotope elimination was best modelled by a mono-exponential decay. The answer is: more successfully than we had expected.On three separate occasions, five zebra finches ( Taenopygia guttata) were injected intraperitoneally with 0.2 ml 0.29 M NaH 13CO 3 solution and placed immediately into respirometry chambers to explore the link between 13C elimination and both O 2 consumption (VO 2) and CO 2 production (VCO 2). By helping to overcome these costs, behavioral flexibility can facilitate the evolution of female choice and male sexual selection in monogamous species, the authors say.įorstmeier adds, “Our study asks how females cope with the situation that their mate preferences are difficult to satisfy. The study is the first to quantify the fitness costs to females of being too picky. However, these “wallflowers” produced the same number of successful fledglings as breeding pairs, on average, because they were able to use alternative reproductive strategies, such as sneaking their eggs into the nests of successful couples. They found that while 31 percent of females experiencing high competition chose to pair with a male of a different dialect, 26 percent refused to settle and remained unpaired throughout the experiment. In each aviary, two song dialects were represented at a 2:1 ratio, such that four females could choose from eight males with the same song dialect (relaxed competition), while the other eight females had to compete over four preferred males (high competition). ![]() The birds were housed in 10 aviaries, each with 12 females and 12 males of the same genetic population but different dialects. To investigate the fitness costs of female choosiness, researchers studied four captive populations of zebra finches ( Taeniopygia guttata), a monogamous species with regional song dialects, in which females prefer to mate with males of the same dialect. Female zebra finches are choosy but flexible when it comes to finding a mate, allowing them to avoid the fitness costs of being too selective when competition for males is high, report Wolfgang Forstmeier at the Max Planck Institute for Ornithology in Germany, and colleagues, in a study in the open-access journal PLOS Biology.įemale mating preferences are thought to drive sexual selection in males, but overly choosy females risk missing out on a mate when competition over preferred males is intense.
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