Ecological replacement as a conservation tool presupposes that nonnative taxa can restore degraded ecosystems by performing the ecological functions of extinct taxa. This assumption is rarely tested however, largely because it is difficult to quantify the functions of species extirpated long ago. Here, we test whether feral South American grey foxes (SAGF), introduced to the Falkland Islands ∼90 years ago, act as unintended ecological replacements for endemic Falkland Islands wolves (FIW), extirpated during the 19th century. Using hair stable isotope ratios as proxies for diet, we show that the isotopic niche space of modern SAGFs almost completely encompasses that of archaic FIWs. However, the former's niche is larger so while SAGFs may play similar ecological roles to FIWs, they probably perform additional functions, which may or may not be desirable. In so doing, we illustrate a generalized framework for using comparative isotopic niche analysis to test for ecological replacement objectively.

中文翻译：

---

披着狐狸皮的狼？使用稳定同位素量化生态替代

生态替代作为保护工具的前提是非本地类群可以通过执行已灭绝类群的生态功能来恢复退化的生态系统。然而，这个假设很少得到检验，主要是因为很难量化很久以前灭绝的物种的功能。在这里，我们测试了大约 90 年前引入福克兰群岛的野生南美灰狐 (SAGF) 是否充当了 19 世纪灭绝的地方性福克兰群岛狼 (FIW) 的意外生态替代品。使用头发稳定同位素比率作为饮食的代理，我们表明现代 SAGF 的同位素生态位空间几乎完全包含古代 FIW 的同位素生态位空间。然而，前者的生态位更大，所以虽然 SAGF 可能扮演与 FIW 相似的生态角色，但它们可能执行额外的功能，这可能是也可能不是可取的。在这样做时，我们说明了使用比较同位素生态位分析来客观地测试生态替代的通用框架。