Comparison of Sexual Reproductive Behaviors in Two Species of Macrobiotidae (Tardigrada: Eutardigrada)
Comparison of Sexual Reproductive Behaviors in Two Species of Macrobiotidae (Tardigrada: Eutardigrada)
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DOI：
10.2108/zs180103
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发表时间：
2019-04-01
影响因子：
0.9
通讯作者：
Matsumoto, Midori
中科院分区：
文献类型：
--
作者：
Sugiura, Kenta;Minato, Hiroki;Matsumoto, Midori
繁殖策略是生物多样性的一个重要方面。在缓步动物中，已知有几种生殖方式，包括有性生殖。然而，缓步动物的交配行为在大多数物种中很少被观察到，在某些情况下，特别是在自由产卵的真缓步动物中，仍然是完全未知的。本研究以两种有性繁殖的缓步动物--副长身缓步动物（Paramacrobiotus sp. TYO strain）和松奈长身缓步动物（Macrobiotus shonaicus）为材料，对它们的求偶、交配行为和染色体形态进行了比较研究。交配行为进行了观察和记录在这两个物种。整个交配过程，包括求偶，被分为五个独立的步骤，这是两个物种共有的，如下：[1]跟踪：雄性跟踪并指向雌性; [2]触摸：雄性与雌性的泄殖腔接触; [3]静止：雌性停止运动，直到雄性射精完成; [4]射精：雄性卷曲其尾部末端并从近距离向泄殖腔射精; [5]收缩：雌性在射精后收缩其腹侧以捕获沉积在泄殖腔附近的外部环境中的精子。在步骤3-4中观察到两个物种之间的一些显著差异。首先，在TYO品系中，在交配后40 min，在M. shonaicus，分别。交配前后染色体形态的比较表明，卵母细胞在这两个物种的中期I被逮捕。精子附着在产卵的绒毛膜内部。
Reproductive strategy is an important aspect of biological diversity. In tardigrades, several reproductive modes, including sexual reproduction, are known. However, tardigrade mating behavior has been observed only rarely in most species, and in some cases, especially in the freely ovipositing eutardigrades, remains entirely unknown. In the present study, we cultured two sexually reproducing tardigrade species that lay eggs freely, Paramacrobiotus sp. TYO strain and Macrobiotus shonaicus, to investigate and compare their courtship, mating, and chromosome morphology. Mating behavior was observed and recorded in both species. The entire mating sequence, including courtship, was categorized into five discrete steps common to two species, as follows: [1] Tracking: the male tracks and orientates toward the female; [2] Touching: the male makes contact with the cloaca of the female; [3] Standstill: the female ceases movement until male ejaculation is complete; [4] Ejaculation: the male curls its caudal end and ejaculates into the cloaca from close range; [5] Contraction: the female contracts its ventral side after ejaculation to capture spermatozoa deposited in the external environment in close proximity to the cloaca. Some notable differences between the two species were observed in the steps 3-4. First, oviposition was observed at 40 min in Paramacrobiotus sp. TYO strain, and a few days after mating in M. shonaicus, respectively. Comparisons of chromosome morphology before and after mating indicated that oocytes are arrested at metaphase I in both species. Spermatozoa attach to the interior of the chorion of laid eggs.