托福阅读考试复习中,很多考生都会选择TPO系列题库作为练习资料。这些内容的练习能够帮助大家更充分地了解托福阅读考试,掌握一些做题的技巧。下面小编为大家整理了托福TPO44阅读passage1参考译文,供大家学习!

  One of the most significant evolutionary events that occurred on Earth was the transition of water-dwelling fish to terrestrial tetrapods (four-limbed organisms with backbones). Fish probably originated in the oceans, and our first records of them are in marine rocks. However, by the Devonian Period (408 million to 362 million years ago), they had radiated into almost all available aquatic habitats, including freshwater settings. One of the groups whose fossils are especially common in rocks deposited in fresh water is the lobe-finned fish.

  地球上曾发生过的最重要的一个进化过程就是水生鱼类到陆地四足动物(有着脊骨的四足生物)的转变。鱼类可能起源于海洋,我们对于它们的最早记录都来自海洋的石头。然而,在泥盆纪(4 亿8 百万年前到3亿6千2 百万年前之间),它们已经散布到几乎所有的水生环境中,包括淡水环境。有一类鱼,它的化石在淡水中的岩石里特别常见,这类鱼被称作总鳍鱼。

  The freshwater Devonian lobe-finned fish rhipidistian crossopterygian is of particular interest to biologists studying tetrapod evolution. These fish lived in river channels and lakes on large deltas. The delta rocks in which these fossils are found are commonly red due to oxidized iron minerals, indicating that the deltas formed in a climate that had alternate wet and dry periods. If there were periods of drought, any adaptations allowing the fish to survive the dry conditions would have been advantageous. In these rhipidistians, several such adaptations existed. It is known that they had lungs as well as gills for breathing. Cross sections cut through some of the fossils reveal that the mud filling the interior of the carcass differed in consistency and texture depending on its location inside the fish. These differences suggest a saclike cavity below the front end of the gut that can only be interpreted as a lung. Gills were undoubtedly the main source of oxygen for these fish, but the lungs served as an auxiliary breathing device for gulping air when the water became oxygen depleted, such as during extended periods of drought. So, these fish had already evolved one of the prime requisites for living on land: the ability to use air as a source of oxygen.

  研究四足动物进化的生物学家对于泥盆纪时期的淡水总鳍鱼非常有兴趣。这些鱼居住在大型三角洲的河道和湖泊中。这些鱼的化石被发现在三角洲的石头中,而这些石头通常都是红色的,因为其中充满氧化铁。这就显示出,这些三角洲形成时期的气候中,湿季和旱季交替出现。如果处在干旱的时期,能够让这些鱼存活下来的任何适应能力都会很有帮助。在这些总鳍鱼中,就存在着几种这样的有益的适应能力。众所周知的是,它们通过肺和腮呼吸。一些化石的横切面显示出,填满残骸内部的淤泥在厚度和构造上存在差异,而这个差异取决于淤泥在鱼体内的位置。这些差别暗示出,在体腔的前端下面存在一个嚢状腔,这个腔只能被解释成其当做肺的功用。毫无疑问,对于这类鱼,腮是氧气的主要来源,但是当水中氧气减少,比如在长期干旱的条件下,肺也起到了一种呼吸辅助器官的作用。所以,这些鱼已经进化出了一种重要的在陆地居住的必备条件:即呼吸空气中的氧气。

  A second adaptation of these fish was in the structure of the lobe fins. The fins were thick, fleshy, and quite sturdy, with a median axis of bone down the center. They could have been used as feeble locomotor devices on land, perhaps good enough to allow a fish to flop its way from one pool of water that was almost dry to an adjacent pond that had enough water and oxygen for survival. These fins eventually changed into short, stubby legs. The bones of the fins of a Devonian rhipidistian exactly match in number and position the limb bones of the earliest known tetrapods, the amphibians. It should be emphasized that the evolution of lungs and limbs was in no sense an anticipation of future life on land. These adaptations developed because they helped fish to survive in their existing aquatic environment.

  这些鱼的第二种适应性能力就是肉鳍。这些鳍很厚实、肉肉的,而且很结实,中间带有骨头。它们可能已经被用来帮助鱼在陆地上缓慢移动,可能已经发达到能让这些鱼从一个几乎干涸的水池缓慢的移动到临近的池塘中,利用新水池中充足的水和氧气来生存。这些鳍最终进化成了短粗的腿。泥盆纪总鳍鱼中,鳍部骨头的数量和位置与最早期的四足动物(两栖动物)完全吻合。重要的是,肺和四肢的进化并非是因为预料到了未来在陆地上生活而产生的。这些适应性能力的进化出来的原因是,它们能够帮助总鳍鱼在当时的水生环境中幸存下来。

  What ecological pressures might have caused fishes to gradually abandon their watery habitat and become increasingly land-dwelling creatures? Changes in climate during the Devonian may have had something to do with this if freshwater areas became progressively more restricted. Another impetus may have been new sources of food. The edges of ponds and streams surely had scattered dead fish and other water-dwelling creatures. ■ A In addition, plants had emerged into terrestrial habitats in areas near streams and ponds, and crabs and other arthropods were also members of this earliest terrestrial community. ■ B Thus, by the Devonian the land habitat marginal to freshwater was probably a rich source of protein that could be exploited by an animal that could easily climb out of water. ■ C Evidence from teeth suggests that these earliest tetrapods did not utilize land plants as food; they were presumably carnivorous and had not developed the ability to feed on plants. ■ D

  什么样的生态压力导致鱼逐渐放弃水生环境、转而在陆地居住呢?如果淡水地区逐渐变少,那么在泥盆纪的气候变化可能与这个进化有关。另一个原因可能是新的食物来源。池塘和小溪边必然有一些零散分散的死亡鱼类以及其他水生生物。此外,植物逐渐转移到溪边和池塘边的陆地环境,并且螃蟹和其他节肢动物也生存在于这种最早期的陆地群落中。所以,在泥盆纪时期,淡水旁边的陆地可能存在大量蛋白质,这些蛋白质可以被那些轻易地从水中爬出来的动物获取并利用。从牙齿中发现的证据指出,这些早期的四足动物不吃陆地上的植物:它们大概都是食肉动物,并且还没有进化出以植物为食的能力。

  How did the first tetrapods make the transition to a terrestrial habitat? Like early land plants such as rhyniophytes, they made only a partial transition; they were still quite tied to water. However, many problems that faced early land plants were not applicable to the first tetrapods The ancestors of these animals already had a circulation system, and they were mobile, so that they could move to water to drink. Furthermore, they already had lungs, which rhipidistians presumably used for auxiliary breathing. The principal changes for the earliest tetrapods were in the skeletal system—changes in the bones of the fins, the vertebral column, pelvic girdle, and pectoral girdle.

  最早的四足动物是如何转变到陆地上生活的?就像很多早期植物(比如莱尼蕨类)一样,它们只产生了部分的变化:它们仍旧与水有很紧密的关系。然而,很多早期陆地植物遇到的问题不适用于这些最早的四足动物。这些动物的祖先已经具备循环系统,能够移动,所以它们能移动到水边饮水。此外,它们已经有了肺,肺可能能够帮助总鳍鱼进行辅助的呼吸。最早的四足动物的主要变化就是骨骼系统的变化,即鳍骨、脊柱、骨盆带和肩带等部位骨骼的变化。

  以上就是今天为大家整理的托福TPO44阅读passage1参考译文相关内容,想要了解更多托福考试资讯、托福备考资料,欢迎及时访问本站!

展开显示全文