Role of sexual selection in relation to immunosuppression of testosterone on evolution of sexual dimorphisms in fish

免疫功能障碍假说（Immunocompatibility Handicap Hypothesis，ICHH）认为，由于第二性征产生所需的免疫抑制性雄激素，具有吸引力的性取向的男性比不那么吸引力的竞争对手更有障碍。ICHH的预测在淡水鱼中进行了测试。本研究结果支持ICHH的假设[1）雌性偏好具有夸张性特征的雄性，2）雌性选择中使用的雄性性特征的表达受雄激素控制，3）雄激素具有免疫抑制作用]。这项研究表明，ICHH是有用的鱼类性二型的进化模型。

The immunocompetence handicap hypothesis (ICHH) assumes that males with attractive sexual ornamentation are more handicapped than their less ornamented rivals because of the immunosuppressive androgens required for the production of secondary sexual characters. The predictions of ICHH were tested in freshwater fishes. The present results supported assumptions of ICHH [1) females prefer males with exaggerative sexual traits, 2) expressions of male sexual traits used in female choice are controlled by androgens, 3) androgens have immunosuppressive effects] in the pale chub Zacco platypus (Cyprinidae). This study suggests that ICHH is useful as a model of evolution of sexual dimorphisms in fishes.