Motility and dynamics of eupyrene and apyrene sperm in the spermatheca of the monandrous swallowtail butterfly Byasa alcinous
Motility and dynamics of eupyrene and apyrene sperm in the spermatheca of the monandrous swallowtail butterfly Byasa alcinous
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DOI：
10.1111/phen.12141
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发表时间：
2016-09-01
影响因子：
1.5
通讯作者：
Watanabe, Mamoru
中科院分区：
文献类型：
--
作者：
Konagaya, Tatsuro;Idogawa, Naoto;Watanabe, Mamoru
鳞翅目雄性昆虫产生两种类型的精子：有核的真核精子和无核的无核精子。虽然无精子是不育的，但这两种类型的精子在交配后都会从精原迁移到精膜。廉价填充物假说是多性生殖物种中无性生殖精子迁移的主要适应性解释，该假说表明，在受精囊中存在大量可活动的无性生殖精子会降低雌性接受再次交配的能力。然而，雄性单性燕尾蝴蝶Byasa Alcinous Klug也会产生无核精子。为了确定无性精子在这些男性中的作用，本研究检查了每种类型精子产生和转移的精子数量以及精子膜中精子的动力学和运动性。阿比林精子约占生产和转移精子的89%，可与多雄物种相媲美。两天龄的雄性幼虫将大约17000个真核精子和23万个无核精子转移到一个精囊；大约5000个真核和47000个无核精子到达精囊。交配8天后，大多数真核精子仍留在精囊内，其中四分之一仍然活跃。然而，到达受精囊后，无精子的数量减少，剩下的精子失去活力。因此，在交配后第8天，没有发现可活动的无性精子。无性生殖精子在精荚中的高比例，以及在精子迁移中的比例，表明无性生殖精子的产生和迁移不仅仅是一种进化的退化特征。讨论了无性精子在单性物种中的可能功能。
Lepidopteran males produce two sperm types: nucleated eupyrene sperm and non-nucleated apyrene sperm. Although apyrene sperm are infertile, both sperm types migrate from the spermatophore to the spermathecal after copulation. As a dominant adaptive explanation for migration of apyrene sperm in polyandrous species, the cheap filler hypothesis suggests that the presence of a large number of motile apyrene sperm in the spermatheca reduces female receptivity to re-mating. However, apyrene sperm are also produced in males of the monandrous swallowtail butterfly Byasa alcinous Klug. To identify the role of apyrene sperm in these males, the present study examines the number of spermatozoa produced and transferred and the dynamics and motility of spermatozoa in the spermatheca for each type of sperm. Apyrene sperm represents approximatey 89% of the sperm produced and transferred, which is comparable to polyandrous species. Two-day-old males transfer approximately 17 000 eupyrene and 230 000 apyrene spermatozoa to a spermatophore; approximately 5000 eupyrene and 47 000 apyrene spermatozoa arrive at the spermatheca. Eight days after copulation, most eupyrene spermatozoa remain in the spermatheca and a quarter of them are still active. However, the number of apyrene spermatozoa decreases and those remaining lose their motility after the arriving at the spermatheca. Consequently, 8 days after copulation, no motile apyrene sperm are found. The high proportion of apyrene sperm in the spermatophore, as well as in sperm migration, suggests that the production and migration of apyrene sperm is not simply an evolutionary vestigial trait. The possible functions of apyrene sperm in monandrous species are discussed.