Diverse, continuous, and plastic sexual systems in barnacles.
Diverse, continuous, and plastic sexual systems in barnacles.
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藤壶的多样化、连续性和可塑性系统。
DOI：
10.1093/icb/ict016
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发表时间：
2013
影响因子：
2.6
通讯作者：
S. Yamaguchi
中科院分区：
文献类型：
--
作者：
Yusa;M. Takemura;K. Sawada;S. Yamaguchi
藤壶（甲壳纲：Thoracica）表现出不同的性系统，包括同时雌雄同体、雌雄同体（雌雄同体 + 雄性）和雌雄同体（雌性 + 雄性）。当雄性出现时，它们总是比同种雌雄同体或雌性小得多（称为矮雄性）。自从达尔文做出这一发现以来，许多科学家都对这种多样性着迷。在这项研究中，我们概述了（1）藤壶性系统的多样性，（2）某些属或物种中不同性系统之间的连续性，以及（3）几个物种中性表达的可塑性。首先，虽然大多数藤壶是雌雄同体，但理论和实证研究都表明雌性和矮化雄性往往出现在交配群体较小的物种中。雌雄同体之间的低精子竞争和很少的机会充当雄性都与小群体规模有关，并被认为分别是促进矮化雄性和纯雌性进化的力量。其次，在某些藤壶类群中，雌雄同体和矮化雄性之间的区别尚不清楚，因为矮化雄性有可能成为雌雄同体。由于许多藤壶物种倾向于先雄同时雌雄同体（首先发育雄性功能，然后在不放弃雄性功能的情况下添加雌性功能），因此在这种情况下，侏儒雄性最好被描述为潜在的雌雄同体，由于对同种的依恋，它们更早地阻止生长并强调雄性功能。这可能有利于宿主个体的卵子受精。在某些物种中，雌雄同体和雌性之间的区别也可能变得模糊。第三，性别分配和阴茎形态在某些物种中是可塑的。我们还报告了对有蒂藤壶Octolasmis angulata 小个体的移植实验结果，这表明移植到同种个体上的个体比对照个体发育出更长更宽的阴茎。总体而言，藤壶性系统的多样性、连续性和可塑性是了解性系统多样性的进化和维持的重要来源。
Barnacles (Crustacea: Thoracica) show diverse sexual systems, including simultaneous hermaphroditism, androdioecy (hermaphrodites + males), and dioecy (females + males). When males occur, they are always much smaller (called dwarf males) than conspecific hermaphrodites or females. Ever since Darwin made this discovery, many scientists have been fascinated by such diversity. In this study, we provide an overview of (1) the diversity of sexual systems in barnacles, (2) the continuity between different sexual systems in some genera or species, and (3) the plasticity in sexual expression in several species. First, although most barnacles are hermaphroditic, both theoretical and empirical studies suggest that females and dwarf males tend to occur in species with small mating groups. Low sperm competition among hermaphrodites and little chance to act as a male are both associated with small group sizes and identified as the forces promoting the evolution of dwarf males and pure females, respectively. Second, in some groups of barnacles, the distinction between hermaphrodites and dwarf males is unclear because of the potential of dwarf males to become hermaphrodites. As many barnacle species tend toward protandric simultaneous hermaphroditism (develop male function first and then add female function without discarding male function), the dwarf males in such cases are best described as potential hermaphrodites that arrest growth and emphasize male function much earlier because of attachment to conspecifics. This is presumably advantageous in fertilizing the eggs of the host individuals. The distinction between hermaphrodites and females may also be obscured in some species. Third, sex allocation and penial morphology are plastic in some species. We also report the results of a transplanting experiment on small individuals of the pedunculate barnacleOctolasmis angulata, which suggests that individuals transplanted onto conspecifics developed longer and broader penises than did control individuals. Overall, the diversity, continuity, and plasticity in the sexual systems of barnacles are sources of important insights into the evolution and maintenance of the diversity of sexual systems.