Threshold dimorphism in ejaculate characteristics in the squid Loligo bleekeri
Threshold dimorphism in ejaculate characteristics in the squid Loligo bleekeri
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DOI：
10.3354/meps06971
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发表时间：
2007-01-01
影响因子：
2.5
通讯作者：
Sakurai, Yasunori
中科院分区：
文献类型：
--
作者：
Iwata, Yoko;Sakurai, Yasunori
男性二态性被认为与不同的生殖行为有关。不同的生殖行为促进了精子竞争的不对称，受精成功率的差异可能促进与每种生殖行为相关的射精特征的适应。利用异速生长分析，我们发现雄性Loligo bleekeri乌贼（一种具有与体型相关的另类交配行为的头足类物种）明显存在射精二态性。内部性状存在形态开关点：体型较大的个体比体型较小的个体产生不连续的更长精囊，但除了双峰体型外，外部性状（鳍长、鳍宽、头宽、套宽、触手长和尾轴长）没有发现开关点。这个明确的内部开关点可能是对低脂鱿鱼特有的另类交配行为的适应，在这种交配行为中，雄性使用不同的交配策略将精子囊传递到雌性体内和体表的不同精子储存位置。我们的研究结果表明，不同的生殖行为可以导致内部特征的形态调整。
Male dimorphism has been thought to correlate with alternative reproductive behaviors. Alternative reproductive behaviors promote asymmetry in sperm competition, and the differences in fertilization success could promote adaptations in ejaculate characteristics in relation to each reproductive behavior. Using allometric analysis, we show that ejaculate dimorphism clearly exists in males of the squid Loligo bleekeri, a cephalopod species with body size-related alternative mating behaviors. A morphological switch point was detected for internal characters: larger individuals produced discontinuously longer spermatophores than did smaller individuals, although no switch point was detected for external characteristics (fin length, fin width, head width, mantle width, tentacle length and hectocotylus length) except for bimodal body size. This clear internal switch point could be an adaptation to the characteristic alternative mating behaviors of loliginid squid, in which males use different mating tactics to pass spermatophores to different sperm storage sites in and on the females. Our results indicated that alternative reproductive behaviors can result in morphological adjustment in internal characteristics.