Dimorphic sperm-transfer strategies and alternative mating tactics in loliginid squid
Dimorphic sperm-transfer strategies and alternative mating tactics in loliginid squid
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鱿鱼的二态性精子转移策略和替代交配策略
DOI：
10.1093/mollus/eyu072
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发表时间：
2015
影响因子：
1.2
通讯作者：
Paul Shaw
中科院分区：
文献类型：
--
作者：
Yoko Iwata;Yasunori Sakurai;Paul Shaw
动物通常在雌性体内只有一个精子储存点，但雌性乌贼同时拥有两个不同的精子储存点。使用两个精子储存地点与雄性交配行为的选择有关：大的配偶保护雌性，并在产卵前将精子囊放在输卵管内，而小的“运动鞋”雄性将精子囊放在雌性手臂顶部嘴巴周围的膜上，那里有一个精囊。先前的研究表明，配偶雄性和运动鞋雄性之间的精子包囊和精子形态存在差异。在这里，我们展示了这种鱿鱼的雄性精子转移策略的新的二分适应，与雌性使用两个不同的精子储存地点有关。从小球鞋雄性的精囊中射出的精囊具有明显的二态性：从小于12毫米的小球鞋雄性的精囊中射出的精囊均呈水滴状，而从大于12毫米的大球鞋雄性的精囊中射出的精囊均呈绳状。此外，水滴状的精囊底部有脊椎，这可能会降低它从雌性体表脱落的风险。我们的研究结果表明，精子储存地点的存在，以及相关的生物和环境因素，导致了精子转移策略的进化。
Animal species usually have a single sperm-storage site in the female body, but females of the squidHeterololigo bleekeripossess two distinct sperm-storage sites simultaneously. Use of two sperm-storage sites correlates with alternative male mating behaviours: large consorts guard females and place spermatophores inside the oviduct just before spawning, whereas small ‘sneaker’ males place spermatophores on the membrane around the female's mouth within the arm crown, where a seminal receptacle is present. Previous work showed that spermatophore and sperm morphology diverge between consort and sneaker males. Here we show novel dichotomous adaptations in the sperm-transfer strategy of males of this squid, associated with the use of two distinct sperm-storage sites on females. The spermatangia ejaculated from spermatophores were clearly dimorphic: all spermatangia ejaculated from spermatophores smaller than 12 mm from small sneaker males were drop-shaped, whereas all spermatangia from spermatophores longer than 12 mm from larger consort males were rope-shaped. In addition, the drop-shaped spermatangia were distinct in having a spine on their base, which might reduce the risk of it being shed from the female's body surface. Our findings suggest that existence of alternative sperm-storage sites, and related biological and environmental factors, lead to the evolution of divergent sperm-transfer strategies.