Ejaculate allocation in Brachyura: What do males of Metacarcinus edwardsii respond to?

IF 16.4 1区化学 Q1 CHEMISTRY, MULTIDISCIPLINARY

Accounts of Chemical Research Pub Date : 2018-05-03 DOI:10.3354/AB00693

L. Pardo, M. P. Riveros, O. Chaparro, Katrin Pretterebner

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引用次数: 9

Abstract

In polygynous species, the sperm economy hypothesis predicts that males can adjust the amount of their ejaculate during copulation in response to (1) individual traits of females according to potential female fecundity, (2) future mating opportunities, and (3) risk of sperm competition. We tested this hypothesis in the crab Metacarcinus edwardsii by performing laboratory mating experiments to compare the response of males (sperm number and ejaculate weight delivered) in 3 sex-ratio scenarios: (1) equal, 1 female:1 male; (2) male-biased, 1 female:2 males; and (3) female-biased, 2 females:1 male. First, we determined if any variable, or an interaction between variables, could explain the variation in sperm or ejaculate amount delivered under an equal sex ratio. Second, we contrasted the ejaculate allocation among different sex-ratio scenarios. Under an equal sex ratio, males of M. edwardsii did not adjust their ejaculate allocation in response to any female trait. Male size was positively related to ejaculate delivery, indicating that the pair of vasa deferentia has ejaculate reserves that scale exponentially with male size. However, larger males delivered disproportionally more seminal fluid than sperm. Under a female-biased sex ratio, males did not show plasticity in their ejaculate allocation, but they increased their ejaculate investment (23%) per female under a male-biased sex ratio (i.e. risk of sperm competition). M. edwardsii presented a low level of ejaculate allocation, responding only when competitive males were perceived. In species with trans-molt sperm retention and long ejaculate storage, the risk of sperm competition is present all the time; therefore, males do not economize ejaculate even if more receptive females are available.

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短尾目动物的射精分配:edwardmetacarcinus的雄性对什么有反应?

在一夫多妻制物种中，精子经济假说预测雄性在交配过程中可以根据以下因素调整射精量:(1)雌性的个体特征，根据雌性的潜在繁殖力，(2)未来的交配机会，(3)精子竞争的风险。我们在爱德华元蟹(Metacarcinus edwardsii)身上进行了实验室交配实验，比较了三种性别比例情况下雄性的反应(精子数量和射精重量):(1)雌雄比例相等;(2)男性偏倚，女性1人，男性2人;(3)女性偏倚，女性2:男性1。首先，我们确定是否有任何变量，或者变量之间的相互作用，可以解释在性别比例相等的情况下精子或射精量的变化。其次，我们对比了不同性别比例情景下的射精分配。在性别比例相等的情况下，爱德华m.s wardsii的雄性不会根据雌性的任何特征来调整它们的射精分配。雄性的大小与射精量呈正相关，表明这对输精管的射精量随雄性的大小呈指数级增长。然而，体型较大的雄性产生的精液比精子多得不成比例。在女性性别比例偏大的情况下，男性在射精分配上没有表现出可塑性，但在男性性别比例偏大的情况下(即精子竞争的风险)，男性增加了每个女性的射精投资(23%)。M. edwardsii表现出低水平的射精分配，只有在看到有竞争力的雄性时才有反应。在具有脱毛精子保留和长时间射精储存的物种中，精子竞争的风险一直存在;因此，即使有更容易接受的雌性，雄性也不会节省射精。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Accounts of Chemical Research 化学-化学综合

CiteScore

31.40

自引率

1.10%

发文量

312

审稿时长

2 months

期刊介绍： Accounts of Chemical Research presents short, concise and critical articles offering easy-to-read overviews of basic research and applications in all areas of chemistry and biochemistry. These short reviews focus on research from the author’s own laboratory and are designed to teach the reader about a research project. In addition, Accounts of Chemical Research publishes commentaries that give an informed opinion on a current research problem. Special Issues online are devoted to a single topic of unusual activity and significance. Accounts of Chemical Research replaces the traditional article abstract with an article "Conspectus." These entries synopsize the research affording the reader a closer look at the content and significance of an article. Through this provision of a more detailed description of the article contents, the Conspectus enhances the article's discoverability by search engines and the exposure for the research.