Life History Evolution in Guppies (Pecilia reticulata)

生命历史进化论是对适能概念的概括，它始于20世纪30年代的S，后发展到80年代的S。适应度现在是用完整的变量来定义的，比如一个基因型增加种群规模的能力。根据这一理论，自然选择可以做一些看似违反直觉的事情。例如，自然选择可能倾向于缩短寿命或减少后代数量，前提是有其他补偿。这项研究的目标是在特立尼达岛的孔雀鱼自然种群中测试生活史理论。“生活史”指的是直接影响后代生产的动物特征，如动物何时开始繁殖、繁殖频率、有多少后代以及投入到每个后代身上的资源。大多数自然人口面临不同的死亡模式，例如成人和青少年的死亡率不同。理论家们已经考虑过，自然选择的这一方面将如何选择生活史特征的变化。由于捕食者的原因，特立尼达不同种群的孔雀鱼在特定年龄段的死亡率似乎存在这样的差异。一些种群的捕食者主要捕食大型、性成熟大小的孔雀类，而另一些种群的捕食者主要捕食小的、未成熟的大小类别。特定大小的捕食似乎会导致特定年龄的死亡率的差异。一种预测是，较高的成人死亡率将有利于那些较早开始繁殖的个体，并将更多的资源用于繁殖，而不是更少地用于自身的生长和维持。这些预测的评估方法是：1)量化这两类地区孔雀鱼生活史模式的差异，2)量化自然种群中孔雀鱼的死亡率，3)改变自然溪流中孔雀鱼及其捕食者的分布，以推动生活史模式的演变。该项目已经揭示了自然种群进化变化的过程，并最终将使评估这种变化的机制成为可能。同时，它评估了进化论的一个分支，它包含了对适应性的更一般的定义。

The theory of life history evolution, which began to develop in the 1930's and matured through the 1980's, represents a generalization of the concept of fitness. Fitness is now defined with complete variables, such as the ability of a genotype to increase in population size. Under this theory, natural selection can do seemingly counter-intuitive things. For example, it is possible for natural selection to favor a reduction in lifespan or a reduction in the number of offspring produced, provided that there are other compensations. The goal of this resolves is to test life history theory in natural populations of guppies from the island of Trinidad. "Life history" refers to features of animals that directly influence the production of offspring, such as when animals begin to reproduce, how often they reproduce, how many offspring they have, and the resources devoted to each offspring. Most natural populations are exposed to different patterns of mortality, such as different rates of mortality in adults versus juveniles. Theoreticians have considered how this aspect of natural selection will select for changes in features of the life history. Different populations of guppies in Trinidad appear to experience such differences in age-specific mortality because of their predators. Some populations have predators that prey predominantly on large, sexually mature size classes of guppies while others have predators that feed primarily on small, immature size classes. Size-specific predation appears to cause differences in age-specific mortality rates. One prediction is that higher adult mortality rates will favor those individuals that begin to reproduce earlier and devote more of their resources to reproduction and less to their own growth and maintenance. These predictions are being evaluated by; 1) quantifying the differences in life history patterns of guppies from these two types of localities, 2) quantifying the mortality rates of guppies in natural populations, and 3) changing the distribution of guppies and their predators in natural streams to drive the evolution of life history patterns. This project has already revealed the process of evolutionary change in natural populations and will ultimately make it possible to evaluate the mechanism of this change. At the same time, it evaluates a branch of evolutionary theory which incorporates a more general definition of fitness.