一個月前的打鬥經驗是否會影響Kryptolebias marmoratus魚類之近期

Abstract

打鬥的輸/贏經驗會影響個體在未來打鬥的行為並且降低/增加個體的勝率。一般認為這些經驗效應多為短效性，在幾小時到幾天後即會消失，然而Kryptolebias marmoratus魚類之先前研究，卻顯示輸贏經驗對此魚打鬥行為的影響可能超過一個月。然而這些先前研究中，一個月前有獲勝/落敗經驗的個體同時也具備了較高/較低的打鬥能力，因此無法區分這些個體打鬥行為之差異是源自於一個月前的勝敗經驗或者打鬥能力上的差別。因此，本研究主要目的在於測試一個月前的勝敗經驗是否還會對打鬥行為造成影響。如果一個月前的勝敗經驗仍對打鬥行為有所影響，此經驗亦可能對新的打鬥經驗效應的強弱造成影響；所以本研究同時測試此可能性。實驗結果發現，與一個月前被給予贏經驗的個體相比，一個月前獲得輸經驗的個體在打鬥中展現較低的攻擊性，而且這些（一個月前輸經驗）個體的行為較易受到近期（一天前）打鬥經驗的影響而展現出較明顯的勝者與敗者效應。本研究更進一步發現，兩個月前的勝敗經驗對此魚打鬥行為仍可能造成影響，然而由於此經驗同時伴隨著打鬥能力的差異，無法分辨影響是來自於何項因子。然而此兩個月前之經驗或打鬥能力對來自近期（一天前）打鬥經驗之勝者或敗者效應之顯著性已不再有顯著影響。

A prior winning or losing experience can alter an individual’s behavior in and its probability of winning a subsequent contest. Although these effects have been supposed to be short lived, there is evidence from many previous studies of Kryptolebias marmoratus of an unexplained influence from contests more than a month previously on subsequent contest behavior. These previous experiments, nonetheless, could not distinguish the long-term experience effect from the result of intrinsic fighting ability. This study examined whether/how contest experiences from more than a month previously influence current contest behavior and the magnitude of subsequent winner/loser effects, using fish matched for the outcome of the contest staged two months previously against similarly-sized opponents. The results showed that the winning/losing experience obtained more than a month previously significantly affected both the fish’s subsequent contest behavior and the magnitude of subsequent winner/loser effects. Individuals randomly assigned to receive a losing experience one month previously, were less aggressive; i.e., took longer to initiate displays and attacks and were less likely to escalate contests into physical fights than those assigned a winning experience. Moreover, these individuals displayed stronger winner and loser effects from recent contest experiences. The outcome of the size-matched contests from two months previously also significantly affected current contest behavior but did not influence the significance of the winner or loser effect from recent contest experiences. These results show that contest experience has long-term effect on contest behavior and suggest that the value of information from a recent win or loss may depend on contest history.