基于DNA条形码评估西双版纳国家级自然保护区对樟科植物进化历史的保护

为评估西双版纳国家级自然保护区对樟科这一重要植物类群进化潜力的保护情况, 揭示将物种进化历史纳入生物多样性保护评估的重要性, 本研究通过对西双版纳地区长期的野外调查并查阅标本记录与文献资料, 整理出该地区樟科13属121种物种的具体分布信息, 以植物条形码ITS序列作为分子标记构建了反映整个西双版纳地区樟科植物系统发育关系的系统发育树。我们以此为基础, 从物种层面分析了各物种的进化特异性(evolutionary distinctiveness, ED), 从区域层面分析了自然保护区内、外以及32个行政乡镇的系统发育多样性(phylogenetic diversity, PD), 并结合物种丰富度(species richness, SR)与物种濒危等级, 综合探讨了西双版纳国家级自然保护区对樟科植物进化历史的保护情况。研究发现, 西双版纳国家级自然保护区仅拥有整个西双版纳地区54.5%的樟科物种数, 却保护了该地区樟科植物约88.8%的进化历史, 没有被列入保护范围但却拥有高系统发育多样性的区域有打洛镇、易武乡等。就物种而言, 进化特异性相对较高的19个物种中, 有5种(26.3%)在自然保护区内没有分布; 濒危等级高的54个物种中, 有20种(37.0%)在自然保护区没有分布, 同时拥有高进化特异性和濒危等级的物种仅有1种不在保护区内分布。结果表明, 虽然西双版纳国家级自然保护区对樟科这一植物类群的系统发育多样性以及高保护价值物种的保护较好, 但仍有部分重要樟科植物的进化历史没有涵盖在现有自然保护区范围内; 按照传统方法设定的自然保护区虽能在一定程度上保护樟科物种的进化历史, 但仍然存在与标准化系统发育多样性保护策略相矛盾的地方。因此, 今后在建立自然保护区时, 应将系统发育多样性考虑在内, 以保护生物多样性应对环境变化的潜力。

Assessment of the evolutionary history of Lauraceae in Xishuangbanna National Nature Reserve using DNA barcoding

Global biodiversity is diminishing at an unprecedented rate due to anthropogenic changes in the environment and establishing nature reserve is one of the most effective strategies for reducing biodiversity loss. Xishuangbanna, located in Southwest China, is a famous biodiversity hotspot and Lauraceae plants play an important role in the composition of its forest vegetation. To assess the role of Xishuangbanna National Nature Reserve (XNNR, established in 1958) in the conservation of evolutionary history of Lauraceae and to demonstrate the importance of combining phylogenetic information with biodiversity conservation, the evolutionary distinctiveness (ED), phylogenetic diversity (PD), species richness (SR), and endangerment categories of Lauraceae plants in Xishuangbanna were investigated. Results show that XNNR conserves only half of Lauraceae species (54.5%) found in Xishuangbanna, while 88.8% of PD was protected. However, there are still some areas (e.g. Daluo Town and Yiwu Town) with high PD that are not listed as conservation areas. A total of 19 species with high ED values (> 0.1) were found in Xishuangbanna, of which five species (26.3%) were not conserved in the XNNR, while 20 (37.0%) of 54 endangered species were not distributed in the nature reserve. Only three species with both high ED and endangerment categories were not found in the nature reserve. Our study shows that the XNNR has protected a large proportion of PD and species with high conservation value, however, some important evolutionary history and endangered species of Lauraceae are still not conserved in the XNNR, indicating that the traditional assessment solely based on species richness could not incorporate phylogenetic information completely. We therefore conclude that PD should be considered in establishing nature reserves to maximize the evolutionary potential in an uncertain future.