Data from: Sexual selection of male parental care in giant water bugs

Paternal care can be maintained under sexual selection if it helps in attracting more mates. We tested the hypothesis in two giant water bug species, Appasus major and A. japonicus, that male parental care is sexually selected through female preference for caring males. Females were given an opportunity to choose between two males. In the first test of female mate choice, one male carried eggs on its back, while the other did not. The egg status was switched between these two males in the second test. The experiment revealed that females of both species preferred caring males (i.e. egg-bearing) to non-caring males. Nonetheless, the female mate preference for egg-bearing males was stronger in Appasus major than in A. japonicus. Our results suggest that sexual selection plays an important role in maintaining elaborate paternal care in giant water bugs, but the importance of egg bearing by males in female mate choice varies among species.

若父本照料有助于雄性吸引更多配偶，则其可在性选择作用下得以维持。我们在两种大型负子蝽物种——大负子蝽（Appasus major）和日本负子蝽（A. japonicus）——中检验了下述假说：雄性父本照料可通过雌性对照料雄性的偏好而受到性选择。实验中为雌性提供了在两只雄性间进行选择的机会：在首次雌性择偶实验中，一只雄性背负卵块，另一只则未携带；在第二次实验中，两只雄性的卵块携带状态被互换。实验结果显示，两个物种的雌性均更偏好携带卵块的雄性（即背负卵块的雄性）而非未照料的雄性。尽管如此，大负子蝽雌性对携带卵块雄性的择偶偏好强度要高于日本负子蝽。本研究结果表明，性选择在维持大型负子蝽复杂的父本照料行为中发挥着重要作用，但雄性携带卵块在雌性择偶中的重要性因物种而异。