Del Castillo Raúl Cueva, Núñez-Farfán J
Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Apartado Postal 70-275, México 04510, D.F., México.
Evolution. 1999 Feb;53(1):209-215. doi: 10.1111/j.1558-5646.1999.tb05346.x.
We measured in the field the intensity and mode (i.e., directional, stabilizing) of sexual selection acting jointly on body size and time of sexual maturity in the univoltine, polygamous grasshopper Sphenarium purpurascens. Statistical analyses indicated that selection favored large and protandrous males in terms of a higher mating success. At the same time, evidence of correlational selection acting simultaneously on body size and time to sexual maturity was found. Thus, selection should strengthen the relationship between body size and the time of sexual maturity. Theoretical work suggests the existence of a trade-off between reaching a large size and early sexual maturation in insects. The present study does not support the existence of this kind of trade-off. Recent theoretical and empirical work like the one reported here suggests that such a trade-off may not be necessarily expected if growth rates (which are often assumed to be invariable) are affected by environmental and genetic factors.
我们在野外测量了单化性、多配性的紫翅斯芬蝗（Sphenarium purpurascens）中，共同作用于体型和性成熟时间的性选择强度及模式（即定向、稳定）。统计分析表明，就更高的交配成功率而言，选择青睐体型大且先熟的雄性。同时，发现了对体型和性成熟时间同时起作用的相关选择的证据。因此，选择应会加强体型与性成熟时间之间的关系。理论研究表明，昆虫在达到大体型和早熟之间存在权衡。本研究不支持这种权衡的存在。近期的理论和实证研究，如本文所报道的，表明如果生长速率（通常被认为是不变的）受到环境和遗传因素的影响，那么这种权衡未必会出现。
