Section outline

  • General

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  • 人口结构

    What you will learn 
    ::你会学到什么

    • What is structure
      ::什么是结构
    • How population pyramids and survivorship curves help represent population structure
      ::人口金字塔和幸存者曲线如何帮助代表人口结构

    A diverse group of people, including children and adults, cheerfully posing together.

    Young vs. old. Does it matter?
    ::年轻对老,有关系吗?

    When it comes to populations, yes it does. The age structure (and the sex structure) of a population influences . Can you explain why?
    ::当涉及到人口时,是的。年龄结构(和性别结构)会影响人口。你能解释为什么吗?

    Population Structure
    ::人口结构

    Population growth is the change in the size of the population over time. An important factor in population growth is age-sex structure . This is the number of individuals of each sex and age in the population. The age-sex structure influences population growth. This is because younger people are more likely to reproduce, while older people have higher rates of dying.
    ::人口增长是随着时间推移人口规模的变化,人口增长的一个重要因素是年龄-性别结构,即人口中各性别和年龄的人数,年龄-性别结构影响人口增长,因为年轻人更有可能繁殖,而老年人的死亡率较高。

    Population Pyramids
    ::人口 金字塔

    Age-sex structure is represented by a population pyramid . This is a bar graph, like the one in the Figure . In this example, the bars become narrower from younger to older ages. Can you explain why? 
    ::年龄-性别结构由人口金字塔代表。这是一个条形图,与图中的图一样。在这个例子中,条条从年龄小到年龄大。您能解释为什么吗?

    Population pyramids illustrating age-sex structures with labels for births and deaths.
    A population pyramid represents the age-sex structure of a population. What does a large base represent?

    The Figure shows the structures of three of the world's most populous countries as they were in 2020. It also describes the projection of the population structures of these countries for the year 2060. The population pyramids can be used to assess the age-sex structure of the population by looking at their shape.
    ::图中显示了世界三个人口最多国家与2020年一样的结构,还描述了这些国家2060年人口结构的预测,人口金字塔可以用来通过观察其形状来评估人口的年龄-性别结构。

    Population pyramids for China, India, and the United States, comparing 2020 and projected 2060.
    These population pyramids describe the human population by age and sex for China, India, and United States:
    2020 and Projected 2060 (in millions)

    Survivorship Curves
    ::幸存者曲线

    Another way to show how deaths affect populations is with survivorship curves . These graphs represent the number of individuals still alive at each age. Examples are shown in the Figure . Survivorship curves reflect death rates at different ages.
    ::另一种表明死亡如何影响人口的方式是幸存者曲线。这些图表代表每个年龄仍健在的人数,例如图中。幸存者曲线反映不同年龄的死亡率。

    Graph illustrating three types of survivorship curves based on age and survival rates.
    Survivorship curves reflect death rates at different ages.

    The three types of curves shown in the figure represent different strategies use to adapt to their environment:
    ::图中显示的三种曲线类型代表了为适应环境而采用的不同战略:

    • Type I: Parents produce relatively few offspring and provide them with a lot of care. As a result, most of the offspring survive to so they can reproduce. This pattern is typical of large , including humans.
      ::类型一:父母生育的后代相对较少,并为他们提供许多照顾。因此,大多数后代存活到可以繁殖的地步。这种模式是大型的,包括人类的典型模式。
    • Type II: Parents produce moderate numbers of offspring and provide some . Deaths occur more uniformly throughout life. This pattern occurs in some and many asexual species.
      ::第二类:父母生下少量的后代,并提供一些。 死亡在整个生命中更加一致,这种情况发生在一些和许多非性物种中。
    • Type III: Parents produce many offspring but provide them with little or no care. As a result, relatively few offspring survive to adulthood. This pattern is typical of plants, invertebrates , and many species of .
      ::第三类:父母生下许多子女,但很少或根本没有照顾子女,因此,在成年后存活的后代相对较少,这种模式是植物、无脊椎动物和许多物种的典型。

    The Type I strategy occurs more often in stable environments. The Type III strategy is more likely to occur in unstable environments. Can you explain why?
    ::第一类战略更经常地发生在稳定的环境中。 三类战略更有可能发生在不稳定的环境中。 您能否解释原因 ?

    Can you match the scenarios given below with the correct type of survivorship curves?
    ::您能否将下文给出的情景与正确的幸存者曲线类型相匹配?

     

     

    Summary
    ::摘要

    • The age-sex structure of a population is the number of individuals of each sex and age in the population.
      ::人口的年龄-性别结构是人口中每个性别和年龄的人数。
    • Age-sex structure influences population growth. It is represented by a population pyramid.
      ::年龄-性别结构影响人口增长,人口金字塔代表人口增长。
    • The number of survivors at each age is plotted on a survivorship curve. There are three types of survivorship curves: Type I, Type II, and Type III.
      ::每个年龄的幸存者人数在幸存者曲线上绘制,有三种类型的幸存者曲线:类型一、类型二和类型三。

    Review
    ::回顾

    1. How does the age-sex structure of a population influence growth?
      ::人口的年龄-性别结构如何影响增长?
    2. Assume that a population pyramid has a very broad base. What does that tell you about the population it represents?
      ::假设一个人口金字塔有非常广阔的基础。 这告诉你它所代表的人口是什么?
    3. Compare and contrast Type I and Type III survivorship curves.
      ::比较和对比 类型一和类型三的幸存者曲线。