Katoh Rei, Munehara Hiroyuki, Kohda Masanori
Department of Bio- and Geosciences, Graduate School of Science, Osaka City University, Japan.
Zoolog Sci. 2005 May;22(5):555-61. doi: 10.2108/zsj.22.555.
Telmatochromis temporalis is a bi-parental substrate brooding cichlid endemic to Lake Tanganyika. Paired males were always larger than their mates and had territories around nests against conspecific males. However, males smaller than the paired females were found in 18% of the nests. Here we report a reproductive tactic of these small males. The small males had as heavy gonads as paired males, and the gonad somatic index (GSI) of the small males was much higher than that of the latter. The examinations of the paternity and maternity using microsatellite-DNA as a genetic marker revealed that the small males were not genetically related to the pair members, and sired some young in 3 of 5 nests. These small males did not guard the broods, suggesting that they are likely to perform reproductive parasitism as sneakers. Paired males could not enter their spawning nests due to their large size, which made it difficult to chase out sneakers once they entered the nest. Some males as small as the sneakers were found outside the territories of paired males, and their gonads were quite small. Circumstantial evidence suggests that small males have two alternative investment patterns: investing in gonad to be sneakers, and investing in growth to probably be territorial males.
颞纹丽鱼是坦噶尼喀湖特有的一种双亲护卵丽鱼科鱼类。配对的雄鱼总是比它们的配偶大，并且在巢穴周围有领地，以防同种雄鱼侵犯。然而，在18%的巢穴中发现了比配对雌鱼小的雄鱼。在此我们报告这些小雄鱼的一种繁殖策略。小雄鱼的性腺与配对雄鱼一样重，并且小雄鱼的性腺体指数（GSI）比配对雄鱼高得多。使用微卫星DNA作为遗传标记对亲子关系进行的检测表明，小雄鱼与配对的鱼没有亲缘关系，并且在5个巢穴中有3个巢穴里的一些幼鱼是由小雄鱼所生。这些小雄鱼不守护鱼卵和幼鱼，这表明它们很可能是以偷腥者的身份进行生殖寄生。配对雄鱼由于体型大无法进入它们的产卵巢穴，这使得偷腥者一旦进入巢穴就很难被驱赶出去。在配对雄鱼的领地外发现了一些和偷腥者一样小的雄鱼，它们的性腺非常小。间接证据表明，小雄鱼有两种不同的投资模式：一种是投资性腺成为偷腥者，另一种是投资生长可能成为领地雄鱼。
