Tropical nematode diversity: vertical stratification of nematode communities in a Costa Rican humid lowland rainforest

Comparisons of nematode communities among ecosystems have indicated that, unlike many organisms, nematode communities have less diversity in the tropics than in temperate ecosystems. There are, however, few studies of tropical nematode diversity on which to base conclusions of global patterns of diversity. This study reports an attempt to estimate nematode diversity in the lowland tropical rainforest of La Selva Biological Research Station in Costa Rica. We suggest that one reason previous estimates of tropical nematode diversity were low is that habitats above the mineral soil are seldom sampled. As much as 62% of the overall genetic diversity, measured by an 18S ribosomal barcode, exists in litter and understory habitats and not in soil. A maximum likelihood tree of barcodes from 360 individual nematodes indicates most major terrestrial nematode lineages were represented in the samples. Estimated â speciesâ richness ranges from 464 to 502 within the four 40 by 40 m plots. Directed ...

不同生态系统间的线虫群落比较研究表明，与多数生物不同，热带地区的线虫群落多样性低于温带生态系统。然而，当前可用于支撑全球多样性分布格局结论的热带线虫多样性研究仍较为有限。本研究尝试对哥斯达黎加拉塞尔瓦生物研究站（La Selva Biological Research Station）的低地热带雨林线虫群落多样性进行评估。我们认为，以往热带线虫多样性评估结果偏低的原因之一，是极少对矿质土壤以上的生境开展采样。以18S核糖体条形码（18S ribosomal barcode）为检测手段的结果显示，总计高达62%的总遗传多样性存在于枯落物与林下生境中，而非土壤环境内。基于360条单个线虫条形码构建的最大似然系统发育树表明，样本覆盖了绝大多数主要的陆生线虫演化支系。在四块40米×40米的样地中，估算得到的物种丰富度介于464至502之间。定向研究（原文内容未完整呈现）