The Role of Population Density and Resource Limitation in Predator/Prey-Mediated Life History Traits

生活史理论预测的一个例子是，高成人死亡率将选择在变化中较早成熟和繁殖的个体，这将带来代价，例如寿命缩短或晚年繁殖减少。这一成本被生命早期成功生育的可能性的增加所抵消，因为面对高死亡率，活到高龄的可能性很小。因此，生命史进化理论也对衰老和寿命的进化做出了预测。因为作为理论基础的属性和假设是非常普遍的，所以预测也是普遍的，将适用于包括人类在内的各种生物。它们还为渔业管理等领域提供了重要的见解，因为这种资源开采的后果是死亡率的增加。这种增长将不可避免地在被剥削的种群中选择不受欢迎的特征，例如在较小的规模下早熟。雷兹尼克博士的研究表明，来自高捕食区鱼类的死亡率是前者的两倍。它们成熟的年龄更早，体型更小，并且比那些来自低捕食地点的后代更多。这些结果都与理论预测一致。正在进行的四项实验通过将捕食者添加到低捕食点或将猎物从高捕食点引入到以前缺乏捕食者的低捕食点来评估这些特征。迄今为止的进展表明，这些特征与预期相符。当与其他数据相结合时，例如对世代时间和这些特征的遗传能力的估计，也有可能评估自然界的潜在变化率。这显然比以前认为的要大得多，这在很大程度上是因为这些先前的推断主要是基于化石记录。

9419823 REZNICK One example of a prediction from life history theory is that high adult mortality rates will select for individuals that mature and reproduce earlier in change will carry costs, such as reduced life span or reduced reproduction late in life. This cost is offset by an increase in the probability of successful reproduction early in life, since the odds of living to an advanced age in the face of a high mortality rate are poor. The theory of life history evolution thus also makes predictions about the evolution of aging and life span. Because the properties and assumptions that underlie the theory are very general, the predictions are also general and will apply to a diversity of organisms, including humans. They also provide important insight in areas such as fisheries management, since a consequence of such resource exploitation is an increase in mortality rates. Such increases will inevitably select for undesirable features in exploited populations, such as earlier maturity at a smaller size. Dr. Reznick has shown that fish from high predation localities have mortality rates that are twice as great. They also mature at an earlier age, smaller size, and produce more offspring than those from low predation localities. These results are all consistent with theoretical predictions. Four experiments in progress are evaluating these traits by either adding predators to low predation sites or introducing prey from high predation sites to low predation sites that previously lacked them. Progress to date indicates that these traits are as predicted. When combined with other data, such as estimates of generation time and the heritability of these traits, it is also possible to evaluate the potential rate of change in nature. It is clearly far greater than previously thought, in large part because such prior inferences were based primarily on the fossil record.