In promiscuous species, fitness estimates obtained from genetic parentage may often reflect both pre- and post-copulatory components of sexual selection. Directly observing copulations can help isolate the role of pre-copulatory selection, but such behavioral data are difficult to obtain in the wild and may also overlook post-copulatory factors that alter the relationship between mating success and reproductive success. To overcome these limitations, we combined genetic parentage analysis with behavioral estimates of size-specific mating in a wild population of brown anole lizards (Anolis sagrei). Males of this species are twice as large as females and multiple mating among females is common, suggesting the scope for both pre- and post-copulatory processes to shape sexual selection on male body size. Our genetic estimates of reproductive success revealed strong positive directional selection for male size, which was also strongly associated with the number of mates inferred from parentage. In contrast, a male’s size was not associated with the fecundity of his mates or his competitive fertilization success. By simultaneously tracking copulations in the wild via the transfer of colored powder to females by males from different size quartiles, we independently confirmed that large males were more likely to mate than small males. We conclude that body size is primarily under pre-copulatory sexual selection in brown anoles, and that post-copulatory processes do not substantially alter the strength of this selection. Our study also illustrates the utility of combining both behavioral and genetic methods to estimate mating success to disentangle pre- and post-copulatory processes in promiscuous species.

中文翻译：

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交配成功的行为估计证实了交配前选择的遗传证据

在杂乱的物种中，从遗传亲缘关系中获得的适应性估计通常可以反映性选择的交配前和交配后组成部分。直接观察交配有助于分离交配前选择的作用，但此类行为数据很难在野外获得，而且还可能忽略改变交配成功与繁殖成功之间关系的交配后因素。为了克服这些限制，我们将遗传亲子分析与野生褐变色蜥蜥蜴（Anolis sagrei）群体中特定体型交配的行为估计相结合。该物种的雄性体型是雌性的两倍，并且雌性之间的多次交配很常见，这表明交配前和交配后过程的范围可以影响雄性体型的性选择。我们对繁殖成功率的遗传估计揭示了对雄性体型的强烈正方向选择，这也与从血统推断出的配偶数量密切相关。相比之下，雄性的体型与其配偶的繁殖力或竞争性受精的成功率无关。通过通过来自不同大小四分位数的雄性将彩色粉末转移给雌性来同时跟踪野外的交配，我们独立地证实了体型较大的雄性比体型较小的雄性更有可能交配。我们得出的结论是，棕色变色蜥的体型大小主要受到交配前性选择的影响，而交配后过程不会显着改变这种选择的强度。我们的研究还说明了结合行为和遗传方法来估计交配成功率以解开杂乱物种的交配前和交配后过程的效用。