生态学课件M资料.pptVIP

An organism’s life history is its lifetime pattern of growth and reproduction. The observed in the life history patterns of different species is vast. Some species live for hundreds or even thousands of years, some grow to vast sizes whilst other are minute. Some produce many, tiny offspring whilst others have few, relatively large offspring. How these differences evolve is a key question in ecology. Key Notes Lire history variation M1 LIFE HISTORY 能量分配和 “权衡” 让某一生物在出生后短期内达到大型的成体大小，生产许多大个体后代并长寿是不可能的。分配给生活史一方面的能量不能再用在另一方面，所以在不同生活史特性间进行“权衡”是不可避免的。 It is not possible for an organism to reach a large adult size shortly after birth, produce many large offspring and live to a great age. Energy allocated to one aspect of life history cannot be spent in another, so ‘trade-offs’ between different traits are inevitable. Energy allocation and trade-offs r -选择和 к-选择 r-选择和K-选择理论描述了两种明显的生活史对策，该理论陈述，r-选择种类适应使其种群增长率最大，而к-选择种类适应使其竞争性强。这样，r-选择种类发育快，成体小，后代数量多但体积小，世代时间短。与此相反，к-选择种类发育慢，成体大，后代数量少但体积大，世代时间长。尽管有些种类符合这种理论上的两分法，但也有许多种不符合。由于具有更广预测性的更好的模型出现，该理论已过时了。 Two distinct life history strategies are described by г- and к-selection theory, which states that г- selected species are adapted to maximize the rate of increase of the population size, whilst к-selected species are adapted to be competitive. Thus, r-selected species have rapid development, small adults, many and small offspring and a short generation time. In contrast, к-selected species have slow development, large adult size, few, large offspring and long generation times. Although some species fit this theoretical dichotomy, many do not, and this theory is mow out-dated as better models have wider predictive powers. г- and к-selection 生 殖 价 年龄x的个体的生殖价（RVx）是该个体马上要生产的后代数量加上预期的其在以后的生命过程中要生产的后代数量。个体的生殖价在出生后必然会上升，然后随年龄老化而下降。个体间生殖价的差异提供了一个强有力的生活史对策预报器。 The reproductive value (RVx) of an individual of age x is the number of offspring that individual is expected to produce in the immediate future plus those expected over its rema