| Summary: | 碩士 === 國立臺灣大學 === 生態學與演化生物學研究所 === 101 === Fighting to the death over limited resources is an extreme behaviour in nature. In general, animals do not engage in all-out fights to the limit of their abilities. However, lethal fighting is a common component of mate competition between males of some species of fig-associated wasps. I investigated fighting injuries in three species of fig wasps which are found in the syconia of Ficus benguetensis. It is notable that no Ceratosolen wui males were known to engage in fighting. In contrast, fighting amongst Philotrypesis and Sycoscapter males could lead to serious injuries such as laceration, amputation and decapitation. The male biased syconium sex ratio (SSR) in Philotrypesis and Sycoscapter may have been conducive to extreme fighting. Surprisingly, all three species of males wasps emerged from their natal syconia, which opposes the general assumption that wingless male fig wasps do not disperse. This evidenced male emergence may be followed by a reduction in aggression.
Fig wasps display a wide range of variation in their morphologies and mating strategies. The variation can be so extreme that conspecific winged and wingless males have sometimes been mistaken for different species or even genera. In my study, the mandible lengths of Philotrypesis showed a positive relationship with head width and were continuously distributed. However, the mandible lengths of Sycoscapter showed a positive but discontinuous relationship with head width, indicating that the morph consisted of two types of individuals. As opposed to the prediction, no clear pattern could be found between the body size and risk of injury in Philotrypesis and Sycoscapeter. Small males did not seem to suffer more severe injuries, so there was no advantage to being large during their mortal combat.
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