然而一个同样重要的标准是，物种在随机性全球生态灾难中幸存的能力。
Yet an equally important criterion is the ability of a species to survive random global ecological catastrophes due to impacts.
很多动物学家认为，这是因为，在几乎没有任何现存竞争物种的情况下，有太多的生态小生境可供生存。
Many zoologists believe that it was because so many ecological niches were available with virtually no competition from existing species.
那就是拱顶石物种在生态系统中的作用。
即使新的种群属于不同物种，它也可以大致填补已灭绝种群空出的生态位，保持食物网的完整。
Even if the new population is of a different species, it can approximately fill the niche vacated by the extinct population and keep the food web intact.
当发生燃烧时，它阻止了植物物种之间的竞争发展到某些物种排斥其他物种的程度，减少了生态系统的整体多样性。
When burning occurs, it prevents competition among plant species from progressing to the point where some species exclude others, reducing the overall diversity of the ecosystem.
岛屿分离后，孤立的蜥蜴种群将成为独特的物种，同时也保留了它们祖先的生态适应能力。
After the islands separated, the isolated lizard populations would have become distinct species while also retaining their ancestors' niche adaptations.
生态学家警告说，外表可能具有欺骗性，而且这些外来物种中可能有许多是为人接受的，只是因为没有人记载过其有害影响。
Appearances can deceive, ecologists caution, and many of these exotics may be considered acceptable only because no one has documented their harmful effects.
然而，生态学家警告说，这些表象可能并不是真的；而且，这些外来物种中有许多可能被认为是可接受的，只是因为没有人记载过它们的有害影响。
Yet appearances can deceive, ecologists caution, and many of these exotics may be considered acceptable only because no one has documented their harmful effects.
一些科学家质疑这样的假设，即在自然生态系统中，外来物种的出现是绝对不会被接受的。
A number of scientists question the assumption that the presence of alien species can never be acceptable in a natural ecosystem.
未来的研究应该看看这些蠕虫的行为与生态学，以了解新物种的出现是由什么造成的。
Future research should look at the behavior and ecology of these worms, to understand what caused the new species to arise.
未来的研究应该看看这些蠕虫的行为与生态学，以了解新物种的出现是由什么造成的。
Future research should look at the behavior and ecology of these worms to understand what caused the emergence of new species.
默认情况下，没有外来物种的生态系统被认为是最自然的生态系统。
Ecosystems free of species defined as exotic are, by default, considered the most natural.
长江流经多种不同的生态系统，是诸多濒危物种的栖息地，灌溉了中国五分之一的土地。
As a habitat for many endangered species, the Yangtze River flows through diverse ecosystems and irrigates one-fifth of China's land.
自石器时代以来，人类一直在以惊人的速度消灭物种以及改变生态系统。
Since the Stone Age, humans have been eliminating species and altering ecosystems with astounding speed.
争夺同一生态资源的物种趋向于朝着依赖不同资源的方向进化；而相互竞争的物种会逐渐改变他们的活动范围，使其领地不再重叠。
The physical structure of species competing for resources in the same ecological niche tends to gradually evolve in ways that allow them to occupy different niches.
罗伯特·沃森说：“我们和其他所有物种赖以生存的生态系统的健康正以从未有过的速度恶化。”
"The health of ecosystems on which we and all other species depend is deteriorating more rapidly than ever," Robert Watson said.
由于树种具有不同的、往往是独特的特性，森林物种组成的变化以多种方式影响着生态系统。
Shifts in forest species composition ramify through the ecosystem in many ways because tree species have different, often unique properties.
一个同样重要的标准是，一个物种是否有能力在全球任一生态灾难中生存下来。
An equally important criterion is the ability of a species to survive random global ecological catastrophes due to impacts.
一个现实而紧迫的问题是，许多植物物种还没有被编目，因此它们在生态系统中的位置是未知的。
A real and pressing issue is that many plant species have not yet been cataloged, and so their place in the ecosystem is unknown.
田纳西大学生态学和进化生物学教授唐·史密斯说：“只有一小部分外来物种会在新栖息地引发问题。”
"Only a small percentage of alien species cause problems in their new habitats," said Don Smith, professor of ecology and evolutionary biology at the University of Tennessee.
“只有一小部分外来物种会在它们的新栖息地引发问题。”田纳西大学生态学和进化生物学教授唐·史密斯说。
"Only a small percentage of alien species cause problems in their new habitats,'' said Don Smith, professor of ecology and evolutionary biology at the University of Tennessee.
生态学家曾一度认为，物种多样性使生态系统变得稳定。
At one time, ecologists believed that species diversity made ecosystems stable.
这种新的“群落生态学”强调的是由不同物种组成的群落的组成和结构。
The emphasis of this new "community ecology" was on the composition and structure of communities consisting of different species.
因此，在理解和预测全球变化对南极和亚南极海洋生态系统影响方面，它们是关键物种。
As such, they are key species for understanding and predicting impacts of global change on Antarctic and sub-Antarctic marine ecosystems.
许多生态学家说，这些入侵物种仅次于栖息地的丧失，是对全球生物多样性的最大威胁。
Next to habitat loss, these invasive species represent the greatest threat to biodiversity worldwide, many ecologists say.
一个原始物种可能已经适应了利用一个岛屿上特定的生态位，然后在水上迁徙到其他岛屿定居。
An ancestral species might have adapted to exploit a particular ecological niche on one island and then traveled over water to colonize other islands.
植物平衡了生态系统、保护了流域、减缓了侵蚀、缓和了气候，为许多动物物种提供了庇护所。
Plant life balances ecosystems, protects watersheds, mitigates erosion, moderates climate and provides shelter for many animal species.
对于生态学研究来说，最重要的是收集尽可能多的不同物种的可识别样本。
For ecological studies, the most important factor is collecting identifiable samples of as many of the different species present as possible.
即使是一个生态效率高得多的工业系统，如果它发展得更大，也会比更小、更不生态效率的经济产生更多的垃圾，破坏更多的栖息地和物种。
Even a vastly more ecoefficient industrial system could, were it to grow much larger, generate more total waste and destroy more habitat and species than would a smaller, less ecoefficient economy.
由于其中可能涉及复杂的物种相互作用，通过移除一个关键物种并观察生态系统的变化来确定该物种是有问题的。
Because complex species interactions may be involved, identifying a keystone species by removing the species and observing changes in the ecosystem is problematic.
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