未登录,请登录后再发表信息
最新评论 (0)
播放视频

物种入侵的威胁

The threat of invasive species - Jennifer Klos

覆盖美国南部的巨大藤蔓
Massive vines that blanket the southern United States,
爬上近百英尺高 并将树木连根拔起
climbing as high as 100 feet as they uproot trees and swallow buildings.
吞没房屋贪食的蛇可以吞掉鳄鱼
A ravenous snake that is capable of devouring an alligator.
兔群能将周围的食物吃光
Rabbit populations that eat themselves into starvation.
这不是恐怖电影的情节
These aren’t horror movie concepts.
这是真实的故事
They’re real stories,
但是这类的情况是如何存在于自然界的呢
but how could such situations exist in nature?
接下来举三个物种入侵的实例
All three are examples of invasive species,
生物的有害性并不在取决于它们是什么
organisms harmful not because of what they are,
而取决于它们在哪
but where they happen to be.
比如葛藤
The kudzu vine, for example,
在它的故乡原产地东亚会被各种昆虫食用
had grown quality in its native east Asia, eaten by various insects
而且在寒冬枯萎
and dying off during the cold winters.
但是它时来运转了
But its fortunes changed
当它成为门廊装饰和家畜饲料
when it was imported into the southeastern United States
并被出口到美国东南部时
for porch decoration and cattle feed.
政府为了对抗水土流失甚至鼓励人们种植葛藤
Its planting was even subsidized by the government to fight soil erosion.
由于阳光充足、气候温而且没有天敌
With sunny fields, a mild climate, and no natural predators in its new home,
在它的新家 葛藤的长势失去控制
the vine grew uncontrollably
直到它被称为“吞食南方的植物”
until it became known as the plant that ate the South.
与此类似 佛罗里达州的大沼泽地 作为宠物的缅甸巨蟒
Meanwhile in Florida’s Everglades, Burmese pythons,
由于被其主人释放到野外
thought to have been released by pet owners,
导致了该地生物数量的减少
are the cause of decreasing populations of organisms.
他们成功地战胜了其他顶级捕食者
They’re successfully outcompeting top predators,
比如鳄鱼和黑豹
such as the alligator and panther,
导致了它们食物资源的减少
causing a significant reduction in their food sources.
他们原产地亚洲并不存在这种问题
They’re not a problem in their native Asia
因为疾病、寄生虫和天敌控制了他们的种群规模
because diseases, parasites, and predators help to control their population size.
在澳大利亚 欧洲野兔食用了大量的植物
And in Australia, European rabbits eat so many plants
它们吃光了自己和其他本地动物的食物
that they wipe out the food supply for themselves and other herbivores.
他们在最近才开始增加
They’re a pretty recent addition,
而他们被人引入这块大陆只是因有一个人喜欢猎杀它们
intentionally introduced to the continent because one man enjoyed hunting them.
像缅甸蟒
Like the Burmese pythons,
原产地的多种因素制约了他们的数量
various factors in their native habitat keep their numbers in control.
但是在澳大利亚
But in Australia, the lack of predators
天敌的缺失和适宜全年繁殖的气候
and a climate perfect for year-long reproduction
使得它们的数量飞涨那么
allows their populations to skyrocket.
为什么这样的事情经常发生呢?
So why does this keep happening?
世界上的大多数生态系统
Most of the world’s ecosystems
是由生物经过上千年的共同进化
are the result of millennia of coevolution by organisms,
不断的适应彼此和周围环境
adapting to their environment and each other
最终形成的一个稳定的平衡
until a stable balance is reached.
健康的生态系统通过限制因素维持这一平衡
Healthy ecosystems maintain this balance via limiting factors,
环境条件限制了物种的大小和范围
environmental conditions that restrict the size or range of a species.
这些条件包括了自然地理、
These include things like natural geography and climate,
气候食物供应
food availability,
以及是否存在天敌比如
and the presence or absence of predators.
植物的生长依赖于阳光和土壤营养程度
For example, plant growth depends on levels of sunlight and soil nutrients.
可食用植物的规模影响食草动物数量
The amount of edible plants affects the population of herbivores,
这又影响到以它们为食的食肉动物
which in turn impacts the carnivores that feed on them.
一个正常的捕食者数量能够避免食草动物不会过多
And a healthy predator population keeps the herbivores from becoming too numerous
而吃光所有植物但是
and devouring all the plants.
即便某个因素上一个微小的改变都能破坏这一平衡并且
But even minor changes in one factor can upset this balance,
突然引进的非本地物种
and the sudden introduction of non-native organisms
可是一个相当大的改变
can be a pretty major change.
一个在相对隔绝的栖息地进化的物种
A species that is evolved in a separate habitat
对不同的限制因素
will be susceptible to different limiting factors,
不同的捕食者
different predators,
不同的能量来源
different energy sources,
以及不同的气候都是比较敏感的
and different climates.
如果新栖息地的限制因素不能够限制住物种数量
If the new habitat’s limiting factors fail to restrict the species growth,
那么它将持续增长
it will continue to multiply,
与本土生物竞争资源
out-competing native organisms for resources
并且扰乱整个生态系统
and disrupting the entire ecosystem.
物种偶尔会由于自然因素而将物种引入新栖息地比如
Species are sometimes introduced into new habitats through natural factors,
风暴
like storms,
洋流
ocean currents,
或者气候变迁
or climate shifts.
大部分入侵物种由人类引入
The majority of invasive species, though, are introduced by humans.
通常这是无意间发生的
Often this happens unintentionally,
就像斑马贻贝被货船意外地带进伊利湖一样
as when the zebra mussel was accidentally brought to Lake Erie by cargo ships.
但是由于人们在世界范围内迁移
But as people migrate around the world,
我们通常特意的带上我们的植物或动物一起
we have also deliberately brought our plants and animals along,
极少考虑后果
rarely considering the consequences.
但是现在 我们知道了更多
But now that we’re learning more
生物入侵对生态环境的影响
about the effects of invasive species on ecosystems,
许多政府对动植物运输严密监管
many governments closely monitor the transport of plants and animals,
并且禁止某些物种入境但是
and ban the imports of certain organisms.
是否当初一群某种灵长类动物由强烈的环境变化
But could the species with the most drastic environmental impact
从非洲出发而几乎占领全球呢?
be a group of primates who emerged from Africa to cover most of the world?
我们人类到底是不是入侵物种呢?
Are we an invasive species?

发表评论

译制信息
视频概述
听录译者

收集自网络

翻译译者

收集自网络

审核员

自动通过审核

视频来源

https://www.youtube.com/watch?v=spTWwqVP_2s

相关推荐