評論
打印
Listen to part of a lecture in a biology class.
聽一段生物學課程。
Professor, since we are going to talk about changes in animal populations in the wild, I'd like to ask about something I read in an article online, about how the population size of some animal species can affect other animal species, and how other environmental factors come into play too.
教授，既然我們討論動物種群在自然界的變化，我想問一些關于我在網上讀到的文章，一些物種的群體大小是如何影響其他物種的，而且其他環境因素是如何發揮作用的。
Right. Relationships between animal species in a given ecosystem can get pretty complex.
好的。物種關系在特定的生態系統中可能會非常的復雜。
Because in addition to predator-prey relationships, there are other variables that affect population size.
因為除了生物掠奪關系，還有其他影響種群大小的變數。
The article mentioned that populations of predators and their prey might go up rapidly and then decline all of a sudden.
文章提到捕食者的數量和它們的獵物可能很快地上升，然后突然下降。
Oh. Yeah! I read about that in my ecology class. It happens in cycles. I think that's called a boom-and-bust cycle. Right?
是的！我在生態學課上讀到過，它會周期性地出現。我想這叫做繁榮與蕭條交替循環，對嗎？
OK. Well, hold on a second. First I want to go over some key concepts.
好的，稍等。首先我想復習一些關鍵概念。
Let's say there was a species that had access to plenty of food and ideal conditions.
比如說有一個物種可以獲得很多食物并存在于理想的環境中。
Under those circumstances, its population would increase exponentially, meaning it would increase at an ever-accelerating pace.
在這樣的環境下，它的種群會迅猛增長，意味著它將以持續加速的速度增長。
Wow! That sounds a little scary.
哇！聽起來有點可怕。
Well, it doesn't usually happen. Like you said, a rapid population growth is often followed by a sudden decline.
這通常不會發生，如你所說，一個快速增長的種群隨之而來的經常是突然衰退。
But we do occasionally see exponential growth in nonnative species when they are transplanted into a new environment.
但是我們偶爾會看到當非本地的物種轉移到新環境時，它們會急劇增長。
Um...because they face little competition and have favorable growing conditions.
因為它們不用面對競爭，并且有良好的生長條件。
But for most species, most of the time, resources are finite.
但對于多數物種來說，更多時候資源有限。
There's only so much available...which leads me to my point.
只有一些可以利用，這將引出我要說的重點。
Every ecosystem has what we call a carrying capacity.
每個生態系統都有我們所說的容納量。
The carrying capacity is the maximum population size of a species that can be sustained by the resources of a particular ecosystem.
容納量是物種群體大小的最大化，可以由一個特定生態系統的資源支撐。
Resources are, of course, food, water, and just as important, space.
資源當然是食物、水和同等重要的空間。
Although every species has a maximum rate at which the population of that species could increase, assuming ideal conditions for the species in its environment.
假設物種處于理想環境，然而每個物種都有它種群增長的最大定額。
There are always going to be environmental factors that limit population growth. This is called environmental resistance.
總有環境因素限制種群增長，這叫做環境阻力。
Environmental resistance is important because it stops populations from growing out of control.
環境阻力很重要，因為它阻止種群增長失控。
Factors such food supply, predation and disease affect population size, and can change from year to year or season to season.
如食物供給、捕食和疾病因素可以影響種群大小，而且年年或每季都有變化。
