Allen Benjamin, Kon Mark, Bar-Yam Yaneer
Department of Mathematics and Statistics, Boston University, Boston, Massachusetts 02115, USA.
Am Nat. 2009 Aug;174(2):236-43. doi: 10.1086/600101.
Protecting biodiversity involves preserving the maximum number and abundance of species while giving special attention to species with unique genetic or morphological characteristics. In balancing different priorities, conservation policymakers may consider quantitative measures that compare diversity across ecological communities. To serve this purpose, a measure should increase or decrease with changes in community composition in a way that reflects what is valued, including species richness, evenness, and distinctness. However, counterintuitively, studies have shown that established indices, including those that emphasize average interspecies phylogenetic distance, may increase with the elimination of species. We introduce a new diversity index, the phylogenetic entropy, which generalizes in a natural way the Shannon index to incorporate species relatedness. Phylogenetic entropy favors communities in which highly distinct species are more abundant, but it does not advocate decreasing any species proportion below a community structure-dependent threshold. We contrast the behavior of multiple indices on a community of phyllostomid bats in the Selva Lacandona. The optimal genus distribution for phylogenetic entropy populates all genera in a linear relationship to their total phylogenetic distance to other genera. Two other indices favor eliminating 12 out of the 23 genera.
保护生物多样性涉及保护尽可能多的物种数量和丰度，同时特别关注具有独特遗传或形态特征的物种。在平衡不同的优先事项时，保护政策制定者可能会考虑比较不同生态群落多样性的量化措施。为了实现这一目的，一种措施应随着群落组成的变化而增加或减少，其方式应反映出所重视的方面，包括物种丰富度、均匀度和独特性。然而，与直觉相反的是，研究表明，包括那些强调平均种间系统发育距离的既定指数，可能会随着物种的消除而增加。我们引入了一种新的多样性指数——系统发育熵，它以自然的方式推广了香农指数，以纳入物种亲缘关系。系统发育熵有利于高度独特的物种更为丰富的群落，但它并不主张将任何物种比例降低到低于群落结构相关的阈值以下。我们对比了多个指数在塞尔瓦拉坎多纳叶口蝠群落中的表现。系统发育熵的最优属分布以与其他属的总系统发育距离呈线性关系的方式填充所有属。另外两个指数则倾向于从23个属中消除12个属。
