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  • General

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  • 生物分类

    A group of horses in a grassy field with a blue sky backdrop.
     

    How would you  classify  a horse?
    ::你会如何分类一匹马?

    It's easy enough to classify the horse in the  animal kingdom . That's one level of classification. But what other groups does the horse belong to? Horses also belong to a class—the  mammals . These  animals  all have fur and nurse their young.
    ::很容易在动物王国里对马进行分类。这是一个等级。但是马属于其他什么群体?马也属于一个阶级——哺乳动物。这些动物都有毛皮和幼小的哺乳动物。

    Classification of Life
    ::生活分类

    When you see an  organism  that you have never seen before, you probably put it into a group without even thinking. If it is green and leafy, you probably call it a plant. If it is long and slithers, you probably call it as a snake. How do you make these decisions? You look at the physical features of the organism and think about what it has in common with other organisms.
    ::当你看到一个你以前从未见过的有机体时, 你可能会把它放在一个群中, 而不考虑。 如果它是绿色的, 叶子, 你可能会把它称为植物。 如果它是长的, 滑动的, 你可能会把它称为蛇。 你如何做这些决定? 你看看这个有机体的物理特征, 想想它与其他生物体的共同点。

    Scientists do the same thing when they  classify , or put into categories, living things. Scientists classify organisms not only by their physical features, but also by how closely related they are. Lions and tigers look like each other more than they look like bears, but are lions and tigers related? Evolutionarily speaking, yes.  Evolution  is the change in a  species  over time. Lions and tigers both evolved from a  common ancestor . So it turns out that the two cats are actually more closely related to each other than to bears. How an organism looks and how it is related to other organisms determines how it is classified.
    ::科学家在对生物进行分类或分类时,也会做同样的事情。科学家不仅根据生物的物理特征,而且根据它们之间的紧密关系,对生物进行分类。狮子和老虎看起来比熊长得多,但狮子和老虎有关系吗?从进化角度讲,是的。进化是物种随时间的变化。狮子和老虎都是从共同的祖先演变而来的。因此,事实证明,这两种猫实际上比熊更密切地彼此联系。生物的外观及其与其他生物的关系决定了它们是如何分类的。

    Linnaean System of Classification
    ::林内人分类制度

    People have been concerned with classifying organisms for thousands of years. Over 2,000 years ago, the Greek philosopher Aristotle developed a classification system that divided living things into several groups that we still use today, including mammals,  , and  .
    ::数千年来,人们一直关注生物的分类。 2000多年前,希腊哲学家亚里士多德(Aristodle)开发了一种分类系统,将活物分成若干组,我们今天仍在使用这些组,包括哺乳动物和哺乳动物。

    Carolus (Carl)  Linnaeus  (1707-1778) ( Figure  ) built on Aristotle’s work to create his own classification system. He invented the way we name organisms today, with each organism having a two word name. Linnaeus is considered the inventor of modern  taxonomy , the  science  of naming and grouping organisms.
    ::Carolus (Carl) Linnaeus (1707-1778) Linnaeus (Figure ) 以亚里士多德(Aristotle)创建自己的分类系统的工作为基础。 他发明了我们今天命名生物的方式,每个生物都有两个单词名称。 林内乌斯被认为是现代分类学、命名和分组生物科学的发明者。

    Portrait of Carl Linnaeus, the inventor of modern taxonomy and classification systems.
     
    In the 18th century, Carl Linnaeus invented the two-name system of naming organisms (genus and species) and introduced the most complete classification system then known.

    Linnaeus developed  binomial nomenclature , a way to give a scientific name to every organism. In this system, each organism receives a two-part name in which the first word is the  genus  (a group of species), and the second word refers to one species in that genus. For example, a coyote's species name is  Canis latrans .  Latrans  is the species and  Canis  is the genus, a larger group that includes dogs, wolves, and other dog-like animals. Here is another example: the Japanese maple,  Acer palmatum , and the sugar maple,  Acer saccharum , are both in the same genus and they look similar ( Figure  ). Notice that the genus is capitalized and the species is not, and that the whole scientific name is in italics. Tigers  (Panthera tigris)  and lions  (Panthera leo)  have the same genus name, but are obviously different species. The names may seem strange, but the names are written in a  language  called Latin.
    ::Linnaeus 开发了二元论术语, 这是给每个生物以科学名称的一种方法。 在这个系统中, 每个生物都获得一个由两部分组成的名称, 其中第一个单词是基因( 一组物种), 第二个单词指的是该基因中的一个物种。 例如, 野狼的物种名称是 Canis latrans 。 Latrans 是物种, 而 Canis 是 基因( 包括狗、 狼和其他类似狗的动物) 。 这里还有一个例子: 日本的地图, Acer Palmatum 和 甘蔗地图, Acer sacharum , 都在同一基因中, 它们看起来相似( Figure ) 。 请注意, 基因是资本化的, 物种不是, 整个科学名称在斜体中。 虎( Panthera tigris) 和狮子( Panthera leo) 具有相同的基因名称, 但明显是不同的物种 。 名称看起来很奇怪, 但名称是拉丁语写成的。

    Leaves of sugar maple, Japanese maple, and winged seeds from maple genus.
     
    These leaves are from two different species of trees in the Acer, or maple, genus. The green leaf (far left) is from the sugar maple, and the red leaf (center) are from the Japanese maple. One of the characteristics of the maple genus is winged seeds (far right).

    Modern Classification
    ::现代分类

    Modern taxonomists have reordered many groups of organisms since Linnaeus. The main categories that biologists use are listed here from the most specific to the least specific category ( Figure  ). All organisms can be classified into one of three  , the least specific grouping. The three domains are  Bacteria ,  , and  Eukarya . The  Kingdom  is the next category after the Domain. All life is divided among six kingdoms: Kingdom Bacteria, Kingdom Archaea, Kingdom  Protista , Kingdom Plantae, Kingdom  , and Kingdom Animalia.
    ::自林内乌斯以来,现代分类学家对许多生物群进行了重新排序。生物学家使用的主要类别从最具体类别到最不具体类别(图 ) 列出在这里。 所有生物体都可以分为三个类别之一, 最不具体类别。 三个领域是细菌, 和 Eukarya 。 王国是域之后的下一个类别。 所有生命都分为六个王国: 细菌王国、 Archaea王国、 普罗蒂斯塔王国、 Plantae王国、 王国和动物王国。

    Biological classification from Domain to Species using Homo sapiens as an example.
     
    The left side of the diagram illustrates the classification categories for organisms, with the least specific category at the bottom and the most specific category at the top. On the right side of the diagram is an example of classification using Homo sapiens (humans). Homo is the genus, and sapiens is the only living species of the genus.

    Defining a Species
    ::界定物种

    Even though naming species is straightforward, deciding if two organisms are the same species can sometimes be difficult. Linnaeus defined each species by the distinctive physical characteristics shared by these organisms. But two members of the same species may look quite different. For example, people from different parts of the world sometimes look very different, but we are all the same species ( Figure  ).
    ::尽管命名物种是直截了当的,但决定两种生物是否是同一物种有时可能很难。 林瑙斯用这些生物所共有的独特物理特征来界定每个物种。 但同一物种的两个成员可能看起来大不相同。 比如,来自世界不同地区的人有时看起来非常不同,但我们都是相同的物种(图 ) 。

    So how is a species defined? A  species  is defined as a group of similar individuals that can interbreed with one another and produce fertile  offspring . A species does not produce fertile offspring with other species.
    ::如何定义物种?一个物种被定义为一个由相似的个体组成的群体,可以相互交织并产生繁殖后代。一个物种不会与其他物种产生繁殖后代。

    Group of three children laughing and having fun outdoors.
     
    These children are all members of the same species, Homo sapiens.

    Summary
    ::摘要

    • Scientists have defined several major categories for classifying organisms: domain, kingdom, phylum, class, order, family, genus, and species.
      ::科学家为生物分类界定了若干主要类别:领域、王国、植物、阶级、秩序、家庭、基因和物种。
    • The scientific name of an organism consists of its genus and species.
      ::生物体的科学名称由它的基因和物种组成。

    Review
    ::回顾

    1. Who is the inventor of the modern classification system?
      ::谁是现代分类制度的发明者?
    1. List the classification categories for organisms from the broadest category to the most specific.
      ::从最广义的类别到最具体的类别,列出生物的分类类别。
    1. What is meant by binomial nomenclature?
      ::二进制术语是什么意思?
    1. Define a species.
      ::定义一个物种。