Division of Theoretical Biology, Dept. IFM, Linköping University, SE-58183, Linköping, Sweden.
ELTE-MTA Theoretical Biology and Evolutionary Ecology Research Group, Budapest, Hungary.
Nat Commun. 2022 May 9;13(1):2521. doi: 10.1038/s41467-022-30090-4.
It seems intuitively obvious that species diversity promotes functional diversity: communities with more plant species imply more varied plant leaf chemistry, more species of crops provide more kinds of food, etc. Recent literature has nuanced this view, showing how the relationship between the two can be modulated along latitudinal or environmental gradients. Here we show that even without such effects, the evolution of functional trait variance can erase or even reverse the expected positive relationship between species- and functional diversity. We present theory showing that trait-based eco-evolutionary processes force species to evolve narrower trait breadths in more tightly packed, species-rich communities, in their effort to avoid competition with neighboring species. This effect is so strong that it leads to an overall reduction in trait space coverage whenever a new species establishes. Empirical data from land snail communities on the Galápagos Islands are consistent with this claim. The finding that the relationship between species- and functional diversity can be negative implies that trait data from species-poor communities may misjudge functional diversity in species-rich ones, and vice versa.
从直观上看，物种多样性促进功能多样性似乎是显而易见的：具有更多植物物种的群落意味着植物叶片化学物质的多样性更大，提供更多种类的作物意味着有更多种类的食物等。最近的文献对这一观点进行了细致的研究，表明这两者之间的关系可以沿着纬度或环境梯度进行调节。在这里，我们表明，即使没有这些影响，功能性状方差的进化也可以消除甚至逆转物种多样性和功能多样性之间的预期正相关关系。我们提出的理论表明，基于性状的生态进化过程迫使物种在更加紧密、物种丰富的群落中进化出更窄的性状宽度，以避免与邻近物种的竞争。这种效应非常强烈，以至于每当一个新物种建立时，都会导致整个性状空间覆盖率的降低。来自加拉帕戈斯群岛陆地蜗牛群落的实证数据与这一说法一致。物种多样性和功能多样性之间的关系可能是负相关的，这意味着来自物种贫乏群落的性状数据可能会错误判断物种丰富群落的功能多样性，反之亦然。
