条纹短攀鲈的雄性个体大小、雌性偏好以及雄性之间的竞争

本研究考察了条纹短攀鲈(Trichopsis vittata)雄性个体的身体大小对雌性个体性偏好的影响以及对雄性之间竞争的影响。本研究设立了两种处理来研究雌性个体的性偏好以及雄性之间的竞争。在一种处理中,放入同样大小的雄性个体,而在另一种处理中,放入大小不同的雄性个体。结果表明,雄性个体的大小不影响雌性条纹短攀鲈的性偏好。在对雄性之间竞争的研究中,发现个体较大的个体获胜的次数比较多。在个体大小相同的处理中,雄性之间打斗的持续时间比另一种处理中的打斗持续时间长。对这两种处理中不同对抗行为的比较表明,个体大小相同处理组中的发声、咬、以及总体对抗行为发生得更为频繁。对个体大小不同处理组中的大、小个体的进一步观察也揭示出体型大的个体比体型小的个体有更多的追逐行为和更少的逃脱行为。这些结果表明,在雄性个体比雌性个体大的物种中,体型的性两型可能与雄性之间的竞争有关,而不是与雌性偏好有关。

Male body size,female preference and male-male competition in croaking gouramis Trichopsis vittata

This study examined the role of the male body size in the female sexual preference and male-male competition among croaking gouramis (Trichopsis vittata Cuvier, 1831). Two studies were conducted; in the first males were matched in size, and in the second males of different sizes were placed together. The results showed that male body size did not affect sexual preference among female croaking gouramis. Regarding the male-male competition study, large males won more fights than small ones. Fighting durations between size-matched fish were longer than those between size-mismatched fish. A comparison of different agonistic behaviours of the fish under both treatments showed that sound producing, biting and total agonistic behaviours were found more frequently among the size-matched fish. Further observations of the large and small fish in the size-mismatched group also revealed that large males performed more chasing and less escaping than small ones. These results indicate that sexual size dimorphism in croaking gourami (in which the male is larger than the female), is associated with male-male competition, not with female preference.