Hodgson David J, Rainey Paul B, Buckling Angus
Ecology Group, CEH Oxford, Mansfield Road, Oxford OX1 3SR, UK.
Proc Biol Sci. 2002 Nov 7;269(1506):2277-83. doi: 10.1098/rspb.2002.2146.
Decreasing species diversity is thought to both reduce community productivity and increase invasibility to other species. However, it remains unclear whether identical mechanisms drive both diversity-productivity and diversity-invasibility relationships. We found a positive diversity-productivity relationship and negative diversity-invasibility and productivity-invasibility relationships using microcosm communities constructed from spatial niche specialist genotypes of the bacterium Pseudomonas fluorescens. The primary mechanism driving these relationships was a dominance (or selection) effect: more diverse communities were more likely to contain the most productive and least invasible type. Statistical elimination of the dominance effect greatly weakened the diversity-invasibility relationship and eliminated the diversity-productivity relationship, but also revealed the operation of additional mechanisms (niche complementarity, positive and negative interactions) for particular combinations of niche specialists. However, these mechanisms differed for invasibility and productivity responses, resulting in the invasibility-productivity relationship changing from strongly negative to weakly positive. In the absence of the dominance effect, which may be an experimental artefact, decreasing diversity can have unexpected or no effects on ecosystem properties.
物种多样性的降低被认为既会降低群落生产力，又会增加对其他物种的易入侵性。然而，目前尚不清楚相同的机制是否驱动了多样性-生产力关系和多样性-易入侵性关系。我们使用由荧光假单胞菌的空间生态位专化基因型构建的微观群落，发现了正的多样性-生产力关系以及负的多样性-易入侵性和生产力-易入侵性关系。驱动这些关系的主要机制是优势（或选择）效应：更多样化的群落更有可能包含生产力最高和最不易入侵的类型。对优势效应进行统计消除极大地削弱了多样性-易入侵性关系，并消除了多样性-生产力关系，但也揭示了针对生态位专化特定组合的其他机制（生态位互补、正负相互作用）的运作。然而，这些机制在易入侵性和生产力响应方面有所不同，导致易入侵性-生产力关系从强负相关变为弱正相关。在没有优势效应（这可能是一种实验假象）的情况下，多样性降低可能对生态系统属性产生意想不到的影响或没有影响。
