Many ecosystems today are threatened by invasive species. These newcomers prey on or compete with native species, they carry new parasites and diseases, and even cause extinctions of long-established residents. But why are some species such successful invaders while the advances of other species in foreign territory remain unrecognized?
为了回答这个问题，我们专注于入侵物种的最普遍的例子之一：大鼠。这些啮齿动物几乎在地球上几乎到处都发现，并以对本地生态群落（尤其是对岛屿的生态社区）产生不利影响而闻名。作为他的博士学位论文Toky Randriamoria的一部分，来自Antanarivo大学在马达加斯加中部呆了数月，捕捉了小型哺乳动物。他主要在陷阱中发现的大鼠在农业领域，靠近村庄和天然林中发现的东西。最初是由中世纪阿拉伯半岛的海员引入的，黑人和挪威大鼠超越了马达加斯加。如今，它们几乎出现在岛上的所有天然和人为栖息地中，占某些地区啮齿动物捕获的95％。
Toky collected nearly 600 hair samples of black and Norway rats, which I used to encipher the diet and habitat use of these individuals by stable isotope analysis. Stable isotopes are “one of nature’s ecological recorders” and integrate information on what and where an individual fed during the period of hair growth. We found that rats mixed animal and plant matter and had an extremely broad dietary niche. Indeed, rats covered a dietary niche that was larger than a whole community of around 20 native species! Moreover, rats were opportunistic foragers and changed their diet according to what was available.
But we learnt even more from stable isotope analysis: the signature of some individuals did not match to their habitat. This can only mean that certain individuals move between agricultural fields near villages and natural forests; and with them their parasites and diseases.
Thus overall, our results suggest that due to their flexible and generalist diet and potential movement between natural forest and anthropogenic habitats, rats might affect native forest-dependent Malagasy rodents as competitors, predators, and disease vectors. The combination of these effects helps explain the invasion success of rats and the detrimental effects of this genus on the endemic fauna.
To learn more about the research of Melanie and her co-authors, please explore these links:
评论