Habitat deterioration relaxes resource competition and sexual selection in the threespine stickleback

The operation of sexual selection depends on ecological conditions. Thus, changes in environmental conditions because of human activities can alter the strength and direction of sexual selection, with implications for evolutionary trajectories and the viability of populations. We show that aquatic algal blooms can relax the operation of sexual selection by influencing which males are available to attract females. This is by influencing the ability of males to maintain a resource needed in mate attraction. When we exposed two competing threespine stickleback males (Gasterosteus aculeatus), whose attractiveness to females was known, to either clear or algal-turbid water, nest abandonment was more common in clear water, and it was usually the unattractive male that abandoned his nest. In turbid water, on the other hand, nest abandonments were less common and when they occurred, the probability increased that the attractive male abandoned his nest, and that the unattractive male subsequentl...性选择（sexual selection）的运作依赖于生态条件。因此，人类活动引发的环境变化可改变性选择的强度与方向，进而对演化轨迹及种群生存力产生影响。本研究证实，水生藻华（algal blooms）可通过调控可吸引雌性的雄性个体筛选过程，削弱性选择的作用效果，其机制为干扰雄性维持求偶所需资源的能力。我们将两只已知雌性偏好性的雄性三刺鱼（Gasterosteus aculeatus）置于清澈水体或藻浊水体中开展竞争实验，结果显示：清澈水体中的弃巢行为更为常见，且通常为对雌性缺乏吸引力的雄性发生弃巢；而在浊水体中，弃巢行为相对少见，当确实发生弃巢时，具有吸引力的雄性弃巢的概率会上升，且无吸引力的雄性后续...