Now listen to part of a lecture in a biology class.
ProfessorOK, so let's talk about what happened to a certain type of insect, a moth, a red-and-black moth that lives in Europe. These moths eat a plant called Ragwort and they live in fields where the Ragwort plants grow. Now, there was a group of moth that lives in one of these fields and, for many years, there was a lot of Ragwort growing there. So the moth had plenty to eat and the total number of moth in the field stayed pretty much the same. But then one year it rained a lot less than usual and the Ragwort didn't grow as well. The result was that the moth didn't get enough to eat and many didn't survive but even the ones that did survive didn't lay as many eggs as before. So that year the moth population in the field was quite a bit smaller. The next year, though, the amount of rainfall returned to normal and again many more Ragwort plants grew and, once again, there was a lot available for the moth to eat. So that yearthe moth population increased and the female moth laid many more eggs than the year before. And now, after all that rainfall and plant growth, there were just as many moth in the Ragwort field as there were before." "
Explain the concept of carrying capacity using the example of the moth and Ragwort.
The maximum number of species that a given habitat can support is called carrying capacity. According to the professor, there's a kind of red and black moths that eat a plant called ragworts, and they live in the ragworts field. When there was sufficient ragworts for the moths, the moths' population remained stable over the years, and that stable number of moths' was the field's carrying capacity. However, one year, the balance was disrupted as it rained much less than usual and the production of ragworts decreased, so the moth's population declined because of lack of food and female moths' inability to lay eggs. Then the next year, when the rainfall returned to its previous level, ragworts grew back, and accordingly the number of moths increased and female moths laid more eggs, and soon there were as many moths as the year before the drought, which suggests that carrying capacity of a given habitat changes with the disruption. (179 words)
