Size and Timing of Metamorphosis in Complex Life Cycles: Time Constraints and Variation
Size and Timing of Metamorphosis in Complex Life Cycles: Time Constraints and Variation
复制标题
复杂生命周期中变形的大小和时间：时间限制和变化
作者：
L. Rowe;D. Ludwig
复杂的生命周期以变态时的生态位变化为特征。目前的模型基于最大化增长、最小化死亡率或这些目标的某种平衡来预测变态的最佳大小。这些模型预测了与变形时间无关的最佳大小。生物体生活史上的繁殖和其他重大事件往往受季节的限制，而当时生物体的状态(例如，质量)与适合度有关。因此，生物体的状态以及达到这种状态的时间是这些受时间限制的生命史的中心变量。我们扩展了先前的理论，在三个假设的、复杂的生命周期中包括了显式的时间约束。构建了动态优化模型，以确定生态位转移的最佳时间和质量轨迹。首先，我们考虑了蚂蚁出现时的栖息地转移，在这种情况下，繁殖终止了第一个栖息地的一个生长期，并受到一个季节的限制。其次，我们考虑了两栖动物变态时的栖息地转移，在这种情况下，繁殖终止了第二个栖息地的一个生长阶段，繁殖被限制在一个时间点上。第三，我们将前两种效应结合起来，以延长两栖动物的繁殖期。在这里，确定了两个生态位转移的最佳时间和质量轨迹--从水生栖息地转移到陆地栖息地和从生长阶段转移到生殖阶段。我们提出的分析理论既可以进行定量预测，也可以进行定性预测。问题的结构和解决方案以图形的形式呈现，以帮助直观地解释我们的结果，并将框架扩展到其他参数值和其他生活史示例。一般的结论是，复杂生活史的时间限制导致了随时间变化的生态位转移的最佳大小。在受时间限制的生命历史中，个体在繁殖前某个时间状态的任何变化在繁殖时都会在一定程度上被保存下来。因此，在时间受限的生活史中，我们预计栖息地利用或生活史阶段的最佳切换不仅取决于状态，还取决于达到该状态的时间。
Complex life cycles are characterized by niche shifts at the time of metamorphosis. Current models predict optimal sizes for metamorphosis based on maximizing growth, minimizing mortality, or some balance of these goals. These models predict optimal sizes that are independent of the time of metamorphosis. Reproduction and other major events in the life history of organisms are often constrained to seasons, and the state (e.g., mass) of the organism at that time is related to fitness. Therefore, an organism's state as well as the time that that state is achieved are central variables in these time—constrained life histories. We extend earlier theory to include explicit time constraints in three, hypothetical, complex life cycles. Dynamic optimization models are constructed to determine optimal time and mass trajectories for niche shifts. First, we consider the habitat shift at emergence in mayflies, where reproduction terminates a growth period in the first habitat and is constrained to a season. Second, we consider the habitat shift at metamorphosis in amphibians, where reproduction terminates a growth phase in the second habitat and reproduction is constrained to a single point in time. Third, we combine the first two effects to allow an extended period of reproduction in amphibians. Here optimal time and mass trajectories are determined for two niche shifts–the shift from aquatic to terrestrial habitat and the shift from a growth phase to a reproductive phase. We present analytical theory that allows both quantitative and qualitative predictions. Problem constructions and solutions are presented graphically to aid intuition in interpreting our results and extending the framework to other parameter values and other life—history examples. The general conclusion is that time constraints on complex life histories lead to optimal sizes for niche shifts that vary with time. In time—constrained life histories, any variation in the state of individuals at some time prior to reproduction will be preserved to some degree at reproduction. Therefore, in time—constrained life histories, we expect optimal switches in habitat use or life history stage to depend not only on state but also on the time that state is achieved.
昆虫交配系统的进化
DOI：
10.1093/acprof:oso/9780199678020.003.0004
发表时间：
2014
期刊：
--
影响因子：
--
作者：
Ritchie M
通讯作者：
Ritchie M