DEFERRED REPRODUCTION AS A RESPONSE TO SEXUAL SELECTION IN A CORAL REEF FISH: A TEST OF THE LIFE HISTORICAL CONSEQUENCES
DEFERRED REPRODUCTION AS A RESPONSE TO SEXUAL SELECTION IN A CORAL REEF FISH: A TEST OF THE LIFE HISTORICAL CONSEQUENCES
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珊瑚礁鱼延迟繁殖是对性选择的反应：生命历史后果的测试
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发表时间：
1984
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通讯作者：
R. R. Warner
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作者：
R. R. Warner
理想情况下，在生命早期开始繁殖的个体获得了世代时间较短和降低幼体死亡率的优势。但在许多物种中，雄性比雌性进入生殖的时间要晚得多。这种模式在少数体型较大或年龄较大的雄性垄断交配的物种中最为常见，因此性选择是激烈的(Triver，1972；Warner，1980)。行为生态学的理论表明，在这种情况下，年轻男性几乎不会从生殖活动中获益，因为他们成功的可能性微乎其微。相反，它们应该避免繁殖，最大化它们的觅食时间，并将它们的能量引导到生长、生存或其他可能提高它们地位的因素上(Caughley，1966；Orians，1969；Geist，1971；Selander，1972；Triver，1972；Wiley，1974；Wittenberger，1979)。生活史理论做出了类似的预测：当生殖成功的回报在广泛的生殖努力中都很低时，有机体应该跳过生殖，将能量分配给生长和生存，直到更有利的情况出现(Williams，1966；Gadgil和Bossert，1970；Schaffer，1974；Pianka和Parker，1975；其他参考文献在Stearns，1976)。这些对延迟繁殖的解释假定年轻的雄性比年长的雄性的竞争能力更弱。正如Wiley(1981)指出的那样，年轻雄性避免繁殖的事实并不能证明它们在竞争中处于劣势，特别是在具有确定增长的动物中。其他因素，如对经验的需要，肯定会有助于选择推迟繁殖。然而，当年长的雄性个体大得多时，当前繁殖和未来增长之间的潜在权衡就变得重要起来，因为体型较大的个体往往会在竞争中获胜(例如，兰德，1967；勒博夫，1974；霍华德，1978；华纳和霍夫曼，1980 b)。这就提出了一种对延迟雄性生殖假设适应性的普遍测试：当男性的竞争能力取决于体型时，年轻男性的生殖活动应该与性选择的强度成反比。当性选择不那么激烈时，年轻男性当前的潜在回报就会增加，未来的前景就会降低；因此，他们应该把更大比例的时间和精力用于繁殖。这应该是正确的，只要交配成功随着对生殖活动的投资而显著增加，并应反映在增长放缓或死亡率增加上。相比之下，雌性的时间预算和生活史应该对雄性的性选择强度不太敏感，因为它们的繁殖成功更多地取决于绝对大小而不是相对大小(舍纳，1971；特里弗斯，1972)。这些预测通常是通过性别选择强度似乎不同的物种之间的比较来研究的，但这种比较充满了不受控制的环境变量和不同的进化史的问题(Stearns，1977；Warner，1980)，相反，我通过测量时间预算来测试单个物种的预测
Ideally, individuals that initiate reproduction early in their lifetime gain the advantage of short generation time and reduced juvenile mortality. But in many species, males enter into reproduction much later than do females. This pattern is most common in species where a few larger or older males monopolize matings, and thus sexual selection is intense (Trivers, 1972; Warner, 1980). Theory in behavioral ecology suggests that in this situation younger males have little to gain from reproductive activity, since their probability of being successful is vanishingly small. Instead, they should avoid reproduction, maximize their foraging time, and channel their energy into growth, survival, or other factors likely to elevate their status (Caughley, 1966; Orians, 1969; Geist, 1971; Selander, 1972; Trivers, 1972; Wiley, 1974; Wittenberger, 1979). Life-history theory makes a similar prediction: when the returns in reproductive success are low over a broad range of reproductive effort, an organism should skip reproduction and allocate energy to growth and survival until a more favorable situation occurs (Williams, 1966; Gadgil and Bossert, 1970; Schaffer, 1974; Pianka and Parker, 1975; other references in Stearns, 1976). These explanations of deferred reproduction assume that younger males have less competitive ability than older males. As Wiley (1981) points out, the fact that younger males avoid reproduction is not proof that they are competitively inferior, especially in animals with determinate growth. Other factors, such as the need for experience, could certainly contribute to selection for deferred reproduction. When older males are much larger, however, the potential trade-off between current reproduction and future growth assumes importance because larger individuals tend to win in contests (e.g., Rand, 1967; LeBoeuf, 1974; Howard, 1978; Warner and Hoffman, 1980b). This suggests a general test of the supposed adaptiveness of deferred male reproduction: when male competitive ability depends on size, the reproductive activity ofyounger males should vary inversely with the intensity of sexual selection. When sexual selection is less intense, the current potential rewards for young males are increased and future prospects are decreased; they should therefore direct a larger proportion of their time and energy to reproduction. This should be true as long as mating success increases appreciably with investment in reproductive activities, and should be reflected in slower growth or increased mortality. In contrast, females should have time budgets and life histories that are much more insensitive to the intensity of sexual selection among males, because their reproductive success depends more on absolute size rather than on relative size (Schoener, 1971; Trivers, 1972). These predictions have generally been investigated through comparisons between species that appear to differ in the intensity of sexual selection, but such comparisons are fraught with problems of uncontrolled environmental variables and differing phylogenetic histories (Stearns, 1977; Warner, 1980), Instead, I test the predictions within a single species by measuring the time budgets