Rundle Howard D, Odeen Anders, Mooers Arne Ø
Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada.
BMC Evol Biol. 2007 Mar 9;7:36. doi: 10.1186/1471-2148-7-36.
Despite much empirical attention, tests for indirect benefits of mate choice have rarely considered the major components of sexual and nonsexual offspring fitness relevant to a population. Here we use a novel experimental design to test for the existence of any indirect benefits in a laboratory adapted population of D. melanogaster. Our experiment compared the fitness (mating success, longevity, and productivity) of individuals possessing genomes that derived two generations previously from males that were either entirely successful (studs) or wholly unsuccessful (duds) at achieving mates in three subsequent rounds of mating trials.
Males from the stud treatment were 30% more successful on average at securing mates than males from the dud treatment. In contrast, we found no difference between treatments in measures of productivity or of longevity when measured in a mixed-sex environment. In the absence of females, however, males in the stud treatment outlived males in the dud treatment.
Our results suggest that mating with successful males in this population provides an indirect benefit to females and that, at least in this environment, the benefit arises primarily through the production of more attractive male offspring. However, it is unclear whether this represents solely a traditional sexy sons benefit or whether there is an additional good genes component (with male offspring simply allocating their surplus condition to traits that enhance their mating success). The lack of any detectable differences in female fitness between the two treatments suggests the former, although the longevity advantage of males in the stud treatment when females were absent is consistent with the latter. Determining the effect of this indirect benefit on the evolution of female mate preferences (or resistance) will require comparable data on the direct costs of mating with various males, and an understanding of how these costs and benefits integrate across generations and vary among environments.
尽管受到了诸多实证关注，但对配偶选择间接益处的测试很少考虑与种群相关的有性和无性后代适应性的主要组成部分。在此，我们采用一种新颖的实验设计，来测试在实验室适应环境下的黑腹果蝇种群中是否存在任何间接益处。我们的实验比较了拥有源自两代之前的基因组的个体的适应性（交配成功率、寿命和繁殖力），这些基因组来自在随后三轮交配试验中完全成功（种马）或完全不成功（失败者）获得配偶的雄性。
种马处理组的雄性在获得配偶方面平均比失败者处理组的雄性成功30%。相比之下，当在混合性别环境中测量时，我们发现处理组在繁殖力或寿命测量方面没有差异。然而，在没有雌性的情况下，种马处理组的雄性比失败者处理组的雄性寿命更长。
我们的结果表明，在这个种群中与成功的雄性交配为雌性提供了间接益处，并且至少在这种环境下，这种益处主要通过产生更具吸引力的雄性后代而产生。然而，尚不清楚这仅仅代表传统的性感儿子益处，还是存在额外的优质基因成分（雄性后代只是将其多余的条件分配给增强其交配成功率的性状）。两种处理组之间雌性适应性没有任何可检测到的差异表明是前者，尽管在没有雌性时种马处理组雄性的寿命优势与后者一致。确定这种间接益处对雌性配偶偏好（或抗性）进化的影响，将需要关于与各种雄性交配的直接成本的可比数据，以及对这些成本和益处在代际间如何整合以及在不同环境中如何变化的理解。
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