Sperm removal during copulation confirmed in the oldest extant damselfly, Hemiphlebia mirabilis.
Sperm removal during copulation confirmed in the oldest extant damselfly, Hemiphlebia mirabilis.
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DOI：
10.7717/peerj.2077
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发表时间：
2016
期刊：
影响因子：
2.7
通讯作者：
Cordero-Rivera A
中科院分区：
文献类型：
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作者：
Cordero-Rivera A
交配后性选择可能有利于减少精子竞争的机制，例如雄性物理去除精子。为了研究精子去除的起源，我研究了最古老的豆娘家族中唯一现存的成员——奇异半蛇（Hemiphlebia mirabilis）的生殖行为和精子竞争机制，该物种在 20 世纪 80 年代被认为已经灭绝。该物种表现出争夺竞争行为。雄性会通过短途飞行来寻找雌性，并且雄性和雌性都会表现出明显的“腹部轻弹”。这种行为是雄性在精心设计的交配前求爱过程中使用的，这在蜻蜓目动物中是独一无二的。雌性使用类似的展示来拒绝雄性串联的尝试，但最终通过特定的身体姿势发出接受信号。雄性在求爱过程中用腿固定雌性，与其他豆娘相反，它们永远不会自动断肢。交配时间很短（范围为 4.1-18.7 分钟），并分两个连续阶段进行。在第一阶段，雄性移除部分储存的精子，并在第二阶段（交配结束时）进行授精。男性生殖器舌骨与女性生殖器的大小和形状相匹配，末端有两个角，角上覆盖着面向背部的刺。交配前雌性体内的精子量比第一阶段结束时交配中断的雌性体内储存的精子量大2.7倍，这表明精子被大量清除。这些结果指出，精子去除是异形动物进化中的一个古老特征，可能可以追溯到二叠纪。
Postcopulatory sexual selection may favour mechanisms to reduce sperm competition, like physical sperm removal by males. To investigate the origin of sperm removal, I studied the reproductive behaviour and mechanisms of sperm competition in the only living member of the oldest damselfly family, Hemiphlebia mirabilis, one species that was considered extinct in the 1980s. This species displays scramble competition behaviour. Males search for females with short flights and both sexes exhibit a conspicuous “abdominal flicking”. This behaviour is used by males during an elaborate precopulatory courtship, unique among Odonata. Females use a similar display to reject male attempts to form tandem, but eventually signal receptivity by a particular body position. Males immobilise females during courtship using their legs, which, contrarily to other damselflies, never autotomise. Copulation is short (range 4.1–18.7 min), and occurs in two sequential stages. In the first stage, males remove part of the stored sperm, and inseminate during the second stage, at the end of mating. The male genital ligula matches the size and form of female genitalia, and ends by two horns covered by back-oriented spines. The volume of sperm in females before copulation was 2.7 times larger than the volume stored in females whose copulation was interrupted at the end of stage I, indicative of a significant sperm removal. These results point out that sperm removal is an old character in the evolution of odonates, possibly dating back to the Permian.