Does predation control adult sex ratios and longevities in marine pelagic copepods?
Does predation control adult sex ratios and longevities in marine pelagic copepods?
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DOI：
10.4319/lo.2010.55.5.2193
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发表时间：
2010-09-01
影响因子：
4.5
通讯作者：
Kiorboe, T.
中科院分区：
文献类型：
--
作者：
Hirst, A. G.;Bonnet, D.;Kiorboe, T.
我们通过检测幼体和成体之间性别比例的变化、幼体阶段持续时间的性别差异以及成体在野外和实验室(没有捕食者的情况下)的死亡率来评估海洋中上层桡足类成体性别比偏差的原因。在野外，桡足类晚期(CIV和CV)的性别比通常与性别差异不大(1：1)，或略有男性偏见。相比之下，在成年人中，这些比例通常明显偏向于女性主导。因此，性别比例失衡主要归因于成人的发育过程。非跳甲总科成员的成虫比例特别偏斜；在Oithonidae和Clausocalanidae成员中，这不是由于雄性和雌性成虫生理寿命的差异(即没有捕食者时的实验室寿命)。在Acartia、Oithona和Pseudocalanus属中，我们估计捕食死亡率占成年雄性野外死亡率的69%，而在Acartia、Oithona和Calanus成年雌性中，这一比例为36%。我们得出的结论是：(1)远洋桡足类成体性别比的偏差主要是由于成体阶段的性别差异造成的，而不是由于幼体的差异；(2)成体Acartia、Pusocalanus和Oithona的死亡率是由捕食死亡率决定的，而不是由生理寿命决定的(极端食物限制下除外)；(3)Pusocalanus和Oithona成体雄性死亡率高于雌性，主要是由于对雄性的更高捕食。我们的工作表明，我们现在需要更全面地了解捕食者取食偏好的重要性。
We assess the causes of adult sex ratio skew in marine pelagic copepods by examining changes in these ratios between the juveniles and adults, sexual differences in juvenile stage durations, and mortality rates of adults in the field and laboratory (when free from predators). In the field, late copepodite stages (CIV and CV) commonly have sex ratios that are either not significantly different from equity (1 : 1), or slightly male biased. By contrast, in adults, these ratios are commonly significantly biased toward female dominance. Sex ratio skews are therefore primarily attributable to processes in adults. Members of the non-Diaptomoidea have especially skewed adult ratios; in the members Oithonidae and Clausocalanidae this is not generated from differences between male and female adult physiological longevity (i.e., laboratory longevity when free of predators). In the genera Acartia, Oithona, and Pseudocalanus, we estimate that predation mortality contributed >= 69% of the field mortality rate in adult males, whereas in Acartia, Oithona, and Calanus adult females, this is >= 36%. We conclude that (1) adult sex ratio skew in pelagic copepods is primarily due to differential mortality of the sexes in the adult stage and not in juveniles, (2) mortality rates of adult Acartia, Pseudocalanus, and Oithona are dominated by predation mortality rather than physiological longevity (except under extreme food limitation), and (3) in Pseudocalanus and Oithona, elevated mortality rates in adult males to females is predominantly due to higher predation on males. Our work demonstrates that we now need to develop a more comprehensive understanding of the importance of feeding preferences in predators.