| Abstract: | 同種的雄性時常會使用次級性徵像是武器來競爭配偶、領域和食物。瞭解打鬥機制和衝突解決因子對於解釋次級性徵的演化是很重要的。鍬形蟲科(Lucanidae)中的昆蟲擁有巨大且高度變異的大顎且常被使用於同種競爭中。我們利用序列分析(Sequential analyses)來檢視雞冠細身赤鍬形蟲(Cyclommatus mniszechi)的打鬥路徑和影響打鬥結果的因素。本研究結果指出雄蟲依循三條主要的打鬥路徑以及十一個不同的行為：啟始(I)、行走(W)、接觸(A)、對峙(E)、夾起對手(C)、抬起身體(B)、纏鬥(T)、下壓及推擠(Pr)、靜止不動(S)、追逐(U)以及撤退(R)。在對峙時(E)兩隻雄蟲會用大顎面對彼此，此行為後，雄蟲會直接將對手夾起並甩落木頭(第一路徑)。對峙後，雄蟲會用大顎下壓或推擠其他雄蟲(第二路徑)。當大顎和體型差異很小時，雄蟲之間的互動會進入劇烈打鬥，接著打鬥會持續直到一方被舉起或是撤退(第三路徑)。結果說明打贏的個體在劇烈打鬥中使用三種策略以擊退牠們的對手，而且雄蟲可能會於纏鬥(T)中透過大顎來評估對手的力量。打鬥時間與大顎以及體型的差異呈現負相關。大顎長度在決定鬥爭結果上較體型與家族來得更為重要。關鍵字：次級性徵、同性性擇、武器、大顎、鍬形蟲、鍬形蟲科
Males of conspecific species often used secondary sexual traits such as weapons to compete for mates, territories and food. Understanding the fighting mechanism and determinants of conflict resolution are important in explain the evolution of secondary sexual traits. Insects in the stag beetle family, Lucanidae, have enlarged and highly variable mandibles used for conspecific competition. We examined the fighting sequences of a stag beetle, Cyclommatus mniszechi using sequential analyses and the factors affecting fighting outcomes. Our study suggested that males of C. mniszechi followed eleven distinct behaviors and three main fighting routes. The behaviors included initiation (I), walk (W), approach (A), and encounter (E), clamp (C), body raising (B), tussle (T), pressure and push (Pr), stand still (S), pursue (U), and retreat (R). The two males stood head to head in encounter (E). After this behavior, males can either directly clamp opponents and throw them off the branch (first route), or use mandibles to pressure or push the opponent (second route). When mandible and body size differences between contestants were small, two males proceeded to escalated fights until one male was flipped up by the other male or one male retreated (third route). The results demonstrated that the winner used three strategies to defeat their opponents and the males may assess the strength of opponents through mandibles in tussling stage. The fighting duration was negatively correlated with differences of mandible and body size of the opponents. The mandible size was a more important factor in determining the fighting outcomes than the body size (elytra length) and families (genealogies).Key words: Secondary sexual trait, intraspecific sexual selection, weapon, mandible, stag beetle, Lucanidae |
