Data from: Cryptic diversity in a fig wasp community – functionally differentiated species are sympatric but cryptic species are allopatric

A key debate in ecology centres on the relative importance of niche and neutral processes in determining patterns of community assembly with particular focus on whether ecologically similar species with similar functional traits are able to coexist. Meanwhile, molecular studies are increasingly revealing morphologically indistinguishable cryptic species with presumably similar ecological roles. Determining the geographic distribution of such cryptic species provides opportunities to contrast predictions of niche versus neutral models. Discovery of sympatric cryptic species increases alpha diversity and supports neutral models, while documentation of allopatric/parapatric cryptic species increases beta diversity and supports niche models. We tested these predictions using morphological and molecular data, coupled with environmental niche modelling analyses, of a fig wasp community along its 2700 km latitudinal range. Molecular methods increased previous species diversity estimates from eight to eleven species, revealing morphologically cryptic species in each of the four wasp genera studied. Congeneric species pairs that were differentiated by a key morphological functional trait (ovipositor length) coexisted sympatrically over large areas. In contrast, morphologically similar species, with similar ovipositor lengths, typically showed parapatric ranges with very little overlap. Despite parapatric ranges, environmental niche models of cryptic congeneric pairs indicate large regions of potential sympatry, suggesting that competitive process are important in determining the distributions of ecologically similar species. Niche processes appear to structure this insect community and cryptic diversity may typically contribute mostly to beta rather than alpha diversity.

生态学领域的核心争论之一，聚焦于生态位（niche）与中性过程在调控群落构建模式中的相对重要性，尤其关注具有相似功能性状的生态相似物种能否实现共存。与此同时，分子生物学研究正日益揭示出形态上难以区分的隐存物种（cryptic species），这类物种被推测具备相似的生态功能。明确此类隐存物种的地理分布，可为对比生态位与中性模型的预测结果提供研究契机：若发现同域分布的隐存物种，则会提升α多样性（alpha diversity）并支持中性模型；而记录到异域/邻域分布的隐存物种，则会提升β多样性（beta diversity）并支持生态位模型。我们依托沿2700公里纬度梯度分布的榕小蜂群落的形态学与分子数据，结合生态位建模分析，对上述预测展开了检验。分子手段将此前的物种多样性估算值从8种提升至11种，在所研究的4个榕小蜂属中均发现了形态隐存物种。以关键形态功能性状——产卵器长度（ovipositor length）为区分依据的同属物种对，在大片区域内呈同域共存状态。与之相反，形态相似且产卵器长度相近的物种，通常呈现出邻域分布格局，二者的分布重叠范围极小。尽管呈现邻域分布格局，隐存同属物种对的生态位建模结果仍显示存在大面积潜在同域分布区域，这表明竞争过程在决定生态相似物种的分布格局中发挥着关键作用。研究结果表明，生态位过程似乎塑造了该昆虫群落的结构，而隐存多样性通常主要贡献于β多样性而非α多样性。