The current decline of tropical marsupials in Australia: is history repeating?
The current decline of tropical marsupials in Australia: is history repeating?
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DOI：
10.1111/geb.12088
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发表时间：
2014-02-01
影响因子：
6.4
通讯作者：
Kutt, Alex
中科院分区：
文献类型：
--
作者：
Fisher, Diana O.;Johnson, Chris N.;Kutt, Alex
现代（1500年后）灭绝的哺乳动物中有三分之一（24/77）是澳大利亚物种。这些灭绝仅限于澳大利亚南部，主要是干旱气候地区临界重量范围（35-5500g）的物种。引进的红狐（Vulpes Vulpes）捕食这个范围内的物种，经常受到指责。在没有狐狸的北部热带地区，一波新的种群数量下降正在影响全球相当大比例的有袋动物物种（19种）。我们的目标是测试近期范围下降的合理原因，并确定当前热带地区的下降与过去南部（非热带）地区的下降之间的机制是否不同。我们使用多元回归和随机森林模型来分析与物种范围下降相关的特征，并比较与南部地区过去灭绝相关的变量与当前热带（北部）下降相关的变量。结果相同的两个关键变量，体重和栖息地结构，与整个大陆范围的下降比例相关，但关系的形式因纬度而异。在南方，在降雨较少的开放生境中，中型物种最有可能减少。在热带地区，占据有中等降雨的开放植被（稀树草原）的小型物种正在经历最严重的衰退。在整个非洲大陆，大型物种和那些结构复杂的栖息地（雨林）是安全的。研究结果表明，北方地区不存在中等规模的临界权重范围。由于热带地区没有狐狸，我们认为澳大利亚北部有袋类动物数量的减少与野猫（Felis catus）的捕食有关，而非雨林栖息地的地面植被减少则加剧了野猫的捕食。为了验证这一点，我们建议做一些实验，把猫从一些热带哺乳动物受到威胁的地方移走。我们的研究结果表明，比较分析有助于诊断多物种衰退的潜在原因。
AimA third of all modern (after 1500) mammal extinctions (24/77) are Australian species. These extinctions have been restricted to southern Australia, predominantly in species of critical weight range' (35-5500g) in drier climate zones. Introduced red foxes (Vulpes vulpes) that prey on species in this range are often blamed. A new wave of declines is now affecting a globally significant proportion of marsupial species (19 species) in the fox-free northern tropics. We aim to test plausible causes of recent declines in range and determine if mechanisms differ between current tropical declines and past declines, which were in southern (non-tropical) regions.LocationAustralian continentMethodsWe used multiple regression and random forest models to analyse traits that were associated with declines in species range, and compare variables associated with past extinctions in the southern zones with current tropical (northern) declines.ResultsThe same two key variables, body mass and habitat structure, were associated with proportion-of-decline in range throughout the continent, but the form of relationships differs with latitude. In the south, medium-sized species in open habitats of lower rainfall were most likely to decline. In the tropics, small species that occupy open vegetation with moderate rainfall (savanna) are now experiencing the most severe declines. Throughout the continent, large-bodied species and those in structurally complex habitats (rainforest) are secure.Main conclusionsOur results indicate that there is no mid-sized critical weight range' in the north. Because foxes are absent from the tropics, we suggest that northern Australian marsupial declines are associated with predation by feral cats (Felis catus) exacerbated by reduced ground level vegetation in non-rainforest habitats. To test this, we recommend experiments to remove cats from some locations where tropical mammals are threatened. Our results show that comparative analysis can help to diagnose potential causes of multi-species decline.