高体鳑鲏的性选择问题研究

THE SEXUAL SELECTION OF THE ROSE BITTERLINGS RHODEUS OCELLATUS

以高体鳑鲏为研究对象,分别设置个体大小不同的雌鱼和雄鱼进行性选择实验并验证性选择理论,对雌鱼的怀卵量和雄鱼的空间学习记忆能力也进行了检测。雄鱼对雌鱼的性选择实验结果表明,雄鱼对大个体雌鱼有明显的选择偏好;雄鱼选择雌鱼的次数及停留时间与雌鱼的体长、体高、产卵管长度等特征呈正相关。推测雄鱼是基于直接收益的角度,即最大限度的获得较多的后代及较高的后代存活率对雌鱼进行选择,因为大个体雌鱼拥有长的产卵管及绝对多的处于Ⅴ时相的成熟卵粒,可以提供较多的后代及较高的后代存活率。雌鱼对雄鱼的性选择结果表明,雌性高体鳑鲏对大个体雄鱼也表现出了明显的偏好;雌鱼选择雄鱼的次数及停留时间与雄鱼的体长、体高呈正相关;大个体雄鱼的空间学习记忆能力比小个体强,能更快捷地找到并占领质量好的河蚌而成为领域鱼。从直接收益的观点看,雌鱼选择大个体的雄鱼可能是因为大个体雄鱼可以更加容易、迅速和便捷地寻找到质量好的河蚌引领雌鱼进行产卵,从而保证子代的存活率。

Bitterlings are a group of small fishes in the family Cyprinidae with complicated reproductive behavior. In laboratory, they can be easily manipulated to testsome hypotheses of reproductive behavior. In the present study, we used the rose bitterling Rhodeus ocellatus as model. To understand the general rule of sexual selection in the rose bitter- ling and test some sexual selection hypotheses, we selected females and males with different body sizes. Meanwhile, we also examined the egg counts of females and spatial learning and memory abilities of males. The sexual selection of male showed that male significantly prefer larger females than smaller ones; both selective frequency and staying time of males to females were positively related to some characters displayed by females, such as standard length, body depth, length of ovipositor, etc. Based on the hypotheses of immediate benefits for males, the reason that males preferred to choose larger females to mate can be explained by the facts that larger females have longer ovipositor and more matured eggs, therefore high fecundity. Similarly, females also significantly prefer to choose larger males than smaller ones; both selective frequency and staying time of females to males were positively related to standard length and body depth; larger males were better in spatial learning and memory than smaller ones, which made them have stronger ability in monopolizing good mussels in reproduction. Subsequently, based on the hypotheses of immediate benefits for females, choosing larger males will improve the survival rate of their descendants since larger males can find and occupy good mussels easily and quickly.