Irstea, UR EABX, Equipe FEE, av. de Verdun, F-33612, Cestas, France.
Irstea, UR RECOVER, Equipe FRESHCO, 3275 Route de Cézanne, CS 40061, 13182, Aix en Provence, France.
Sci Rep. 2017 Dec 14;7(1):17611. doi: 10.1038/s41598-017-17975-x.
The impact of species loss on ecosystems functioning depends on the amount of trait similarity between species, i.e. functional redundancy, but it is also influenced by the order in which species are lost. Here we investigated redundancy and sensitivity patterns across fish assemblages in lakes, rivers and estuaries. Several scenarios of species extinction were simulated to determine whether the loss of vulnerable species (with high propensity of extinction when facing threats) causes a greater functional alteration than random extinction. Our results indicate that the functional redundancy tended to increase with species richness in lakes and rivers, but not in estuaries. We demonstrated that i) in the three systems, some combinations of functional traits are supported by non-redundant species, ii) rare species in rivers and estuaries support singular functions not shared by dominant species, iii) the loss of vulnerable species can induce greater functional alteration in rivers than in lakes and estuaries. Overall, the functional structure of fish assemblages in rivers is weakly buffered against species extinction because vulnerable species support singular functions. More specifically, a hotspot of functional sensitivity was highlighted in the Iberian Peninsula, which emphasizes the usefulness of quantitative criteria to determine conservation priorities.
物种丧失对生态系统功能的影响取决于物种之间特征相似性的程度，即功能冗余，但它也受到物种丧失顺序的影响。在这里，我们研究了湖泊、河流和河口鱼类群落的冗余和敏感性模式。模拟了几种物种灭绝情景，以确定易受威胁物种（面临威胁时灭绝可能性较高）的丧失是否比随机灭绝导致更大的功能改变。我们的结果表明，在湖泊和河流中，功能冗余性倾向于随物种丰富度的增加而增加，但在河口则不然。我们证明了：i）在这三个系统中，某些功能特征组合由非冗余物种支持；ii）河流和河口的稀有物种支持独特的功能，而不被优势物种共享；iii）易受威胁物种的丧失可能导致河流中的功能改变大于湖泊和河口。总体而言，由于易受威胁物种支持独特的功能，河流中鱼类群落的功能结构对物种灭绝的缓冲能力较弱。更具体地说，伊比利亚半岛凸显了功能敏感性的热点，这强调了定量标准在确定保护优先级方面的有用性。
