南京環(huán)球雅思：托福閱讀之棲息地話題
OK. That's an instance where a habitat is made less suitable. But now, what about cases where an animal exhibits a clear choice between two suitable habitats. In cases like that, does the preference matter? Well, let's look at the blue warbler. The blue warbler is a songbird that lives in North America. They clearly prefer hardwood forests with dense shrubs, bushes underneath the trees. They actually nest in the shrubs, not the trees. So they're pretty close to the ground, but these warblers also nest in forests that have low shrub density. It's usually the younger warblers that nest in these areas because the preferred spots where there are a lot of shrubs are taken by the older, more dominant birds. And the choice of habitat seems to affect reproductive success. Because the older, more experienced birds who nest in the high density shrub areas have significantly more offspring than those in low density areas, which suggests that the choice of where to nest does have an impact on the number of chicks they have. But a preferred environment doesn't always seem to correlate with greater reproductive success. For example, in Europe, study has been done of blackcap warblers. We just call them blackcaps.
好了，這就是一個關(guān)于棲息地變糟糕的一個例子。但是現(xiàn)在，如果兩個棲息地都很合適，那么動物會表現(xiàn)出怎樣的選擇呢？那么它們的偏好重要嗎？讓我們來看看藍鶯。 藍鶯是一種生活在北美的鳴鳥。它們很顯然的偏好于有著稠密的灌木叢闊葉樹森林。它們通常在灌木叢中筑巢，而不是在樹上。所以，它們傾向于接近地面，但是這些藍鶯也會在有著稀疏灌木叢的森林里面筑巢。通常，年輕的藍鶯將會在這些地方，因為更好的地方已經(jīng)被主流的成年藍鶯所占領(lǐng)。并且這些棲息地的選擇貌似將會影響繁殖的成功與否。因為，更加成熟，更加有經(jīng)驗的鳥將會在高度稠密的灌木叢中筑巢，相較至于在低密度灌木叢筑巢的鳥，它們有著顯著的更多的后代。這也就表明了在那里筑巢對于下一代的數(shù)量有著很大的影響。但是，一個動物偏好的環(huán)境并不總是與高的繁殖率相關(guān)。比方說，在歐洲，關(guān)于黑頂鶯做過了一些研究，我們僅僅把它們叫做黑頂。
南京環(huán)球雅思,南京環(huán)球雅思培訓(xùn)學(xué)校,南京環(huán)球雅思英語,南京環(huán)球雅思培訓(xùn),南京環(huán)球雅思培訓(xùn)中心,南京雅思培訓(xùn),南京雅思,環(huán)球雅思"南京環(huán)球雅思是環(huán)球雅思總部直營分校，以卓越的品牌雄厚的師資，在業(yè)界取得了雅思圣殿的美譽。在全南京環(huán)球雅思摒棄浮夸，追求樸實專業(yè)，憑著國際化的教學(xué)管理、全面的個性咨詢服務(wù)、名師的嚴(yán)謹(jǐn)應(yīng)試教學(xué)風(fēng)格，時時準(zhǔn)確抓住考試信息命脈.環(huán)球雅思南京分校是一家專業(yè)做南京雅思培訓(xùn)的學(xué)校！