章节大纲

  • 常规

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  • 进进 进 进 进

    What you will learn 
    ::你会学到什么

    • How macroevolution happens through gradualism and punctuated equilibrium 
      ::宏观演变如何通过渐进主义和无孔不入的平衡发生

    A road sign showing directions for a fast route and a scenic route.

    Fast or slow?
    ::快速还是慢?

    Which is better, the direct route or the scenic route? Each has its advantages, depending on the situation. And that describes evolution. It can be fast or slow, depending on the situation.
    ::哪个更好, 直接路线还是景色路线? 每一个路径都有其优势, 取决于情况。 这描述了进化。 它可以是快速的,也可以是慢的, 取决于情况。

    Timing of Macroevolution
    ::宏观演变的时间安排

    Is evolution slow and steady? Or does it occur in fits and starts? It may depend on what else is going on, such as changes in climate and geologic conditions.
    ::进化是缓慢而稳定的吗? 或者它是否在开始和开始时发生?它可能取决于其他什么变化,比如气候和地质条件的变化。

    • When geologic and climatic conditions are stable, evolution may occur gradually. This is how thought evolution occurred. This model of the timing of evolution is called gradualism .
      ::当地质和气候条件稳定时,进化可能会逐渐发生。这就是进化思想是如何发生的。进化时间的模型被称为渐进。
    • When geologic and climatic conditions are changing, evolution may occur more quickly. Thus, long periods of little change may be interrupted by bursts of rapid change. This model of the timing of evolution is called punctuated equilibrium . It is better supported by the than is gradualism. This model suggests that niches left open by sudden geologic and climatic changes may be rapidly filled by bursts of evolution. You can see a visualization of this in the Figure
      ::当地质和气候条件发生变化时,进化可能更快。因此,长期的微变可能因快速变化而中断。这种进化时间的模型被称为“穿孔平衡”。进化时间的模型与其说是渐进主义,不如说是支离破碎的平衡。这个模型表明,突变的地质和气候的变化所留下的空隙可以迅速通过进化的暴发来填补。您可以看到图中对此的直观描述。
    Comparison of phyletic gradualism and punctuated equilibrium in evolutionary change over time.
    Two theories of evolutionary change - gradualism vs. punctuated equilibrium - are still debated. The former proposes continuous change, while the latter suggests that species remain constant for long periods of time and that change, when it occurs, is rapid.

    Summary
    ::摘要

    • Darwin thought that evolution occurs gradually. This model of evolution is called gradualism.
      ::达尔文认为进化是逐渐发生的。这种进化模式被称为渐进。
    • The fossil record better supports the model of punctuated equilibrium. In this model, long periods of little change are interrupted by bursts of rapid change.
      ::化石记录更好地支持了无孔不入的平衡模式。 在这个模式中,长期的微小变化会因快速变化而中断。

    Review
    ::回顾

    1. What is gradualism? When is it most likely to apply?
      ::什么是渐进主义?它何时最有可能适用?
    2. Describe the timing of evolutionary change according to the punctuated equilibrium model.
      ::根据标出平衡模型描述进化变化的时间。
    3. Which model of evolution would be predicted to follow the extinction of the dinosaurs? Why?
      ::在恐龙灭绝之后,预计哪种进化模式会随着恐龙的灭绝而变化? 为什么?