| 摘要: | 在求偶場生殖的蛙類中，雌蛙選擇與雄蛙在求偶場的出席率被認為是影響雄蛙交配成功的兩股選汰力量。優良基因假說認為雌性選擇為主要力量，雌蛙偏好具有特定叫聲特徵的雄蛙，這些被偏好的特徵是雄蛙有優良基因的指標，因為鳴叫聲特徵通常受到本身形態的限制。持久力競賽假說則認為雄性競爭為主要力量，出席求偶場所比率高的雄蛙會有較高的機率獲得交配機會，雌蛙對交配對象沒有特徵上的偏好；而雄蛙的出席率是受到本身的身體狀況限制，因此出席率可以反映雄蛙品質。過去的生殖行為研究都是單獨考量這兩個假說，然而，鳴叫聲特徵與求偶場出席率可能是受到同一個雄性的表型特徵所限制，因此這兩者應該是同時存在的。本實驗室過去對於翡翠樹蛙(Rhacophorus prasinatus)的野外調查發現，雄蛙的交配成功與其本身求偶場出席率以及鳴叫聲主音頻有顯著的相關；然而，仍需要操作實驗提供雌性偏好的雄性叫聲特徵是否和適存度有相關性的證據。本計畫的目的為利用回播選擇實驗測試翡翠樹蛙雌蛙對於雄蛙的哪種宣告叫聲特徵有偏好，並進一步探討雄性叫聲特徵是否和適存度有關。整合我們先前的結果，本研究將在求偶場生殖物種中，提供一個整合考量兩種選汰力量的經典案例。
In lek-chorus anurans, female choice and male lek attendance are two sexual selection forces that shape male mating success. The good gene hypothesis (i.e. female choice) proposes that choosy females prefer males with certain call properties that are reliable indicators of high genetic qualities of males because the reliability of the attractive call properties is usually constrained by males’ morphology. Conversely, the endurance rivalry hypothesis (i.e. male-male competition) predicts that females are likely to mate with males that spend more days in a lek regardless of the males’ call properties, and lek attendance could reflect a male’s genetic quality because it is usually constrained by a male’s physical condition. However, these two selection forces should be considered simultaneously in the same system because call attractiveness and lek attendance may be constrained by the same morphological or physical conditions. From our pervious observation of a lek-chorus treefrog Rhacophorus prasinatus, we found that males’ mating successes were significantly correlated with their lek attendance (the proportion of nights a male spent calling in a lek) and the dominant frequency of their advertisement calls. However, the female preference of males’ call properties still need more convened evidence by manipulated experiment, and evidence that correlation between attractive call and offspring fitness is still lack. This study is aim to test whether female prefer any call properties by two-choice playback experiment, and further to examine whether such attractive calls are correlated with offspring fitness in R. prasinatus or not. Integrate with the previous study in male-male competition, this study may provide a rare case which consider both female choice and male-male competition simultaneously to investigated sexual selection in a lek-breeding organism. |
