Ord T J, Stuart-Fox D
Section of Evolution and Ecology, University of California, Davis 95616-8755, USA.
J Evol Biol. 2006 May;19(3):797-808. doi: 10.1111/j.1420-9101.2005.01050.x.
The expression in females of ornaments thought to be the target of sexual selection in males is a long-standing puzzle. Two main hypotheses are proposed to account for the existence of conspicuous ornaments in both sexes (mutual ornamentation): genetic correlation between the sexes and sexual selection on females as well as males. We examined the pattern of ornament gains and losses in 240 species of dragon lizards (Agamidae) in order to elucidate the relative contribution of these two factors in the evolution of mutual ornamentation. In addition, we tested whether the type of shelter used by lizards to avoid predators predicts the evolutionary loss or constraint of ornament expression. We found evidence that the origin of female ornaments is broadly consistent with the predictions of the genetic correlation hypothesis. Ornaments appear congruently in both sexes with some lineages subsequently evolving male biased sexual dimorphism, apparently through the process of natural selection for reduced ornamentation in females. Nevertheless, ornaments have also frequently evolved in both sexes independently. This suggests that genetic correlations are potentially weak for several lineages and sexual selection on females is responsible for at least some evolutionary change in this group. Unexpectedly, we found that the evolutionary loss of some ornaments is concentrated more in males than females and this trend cannot be fully explained by our measures of natural selection.
那些被认为是雄性中存在性选择目标的装饰在雌性中的表达，是一个长期存在的谜题。人们提出了两个主要假说来解释两性中显著装饰的存在（相互装饰）：两性之间的遗传相关性以及对雌性和雄性的性选择。我们研究了240种龙蜥（鬣蜥科）装饰的增减模式，以阐明这两个因素在相互装饰进化中的相对贡献。此外，我们测试了蜥蜴用于躲避捕食者的庇护所类型是否能预测装饰表达的进化损失或限制。我们发现有证据表明，雌性装饰的起源大致符合遗传相关性假说的预测。装饰在两性中同时出现，随后一些谱系通过对雌性装饰减少的自然选择过程，进化出雄性偏向的两性异形。然而，装饰也经常在两性中独立进化。这表明，对于几个谱系来说，遗传相关性可能较弱，雌性的性选择至少对该群体中的一些进化变化负有责任。出乎意料的是，我们发现一些装饰的进化损失在雄性中比在雌性中更集中，而且这种趋势无法通过我们的自然选择指标得到充分解释。
