Darwell C T, Cook J M
School of Biological Sciences, University of Reading, Reading, RG6 6AS, UK.
Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Okinawa, 904-0495, Japan.
Mol Ecol. 2017 Feb;26(3):937-950. doi: 10.1111/mec.13985.
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 vs. 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 processes 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.
生态学中的一个关键争论集中在生态位和中性过程在决定群落组装模式方面的相对重要性，特别关注具有相似功能性状的生态相似物种是否能够共存。与此同时，分子研究越来越多地揭示出形态上难以区分的隐存物种，它们可能具有相似的生态作用。确定这些隐存物种的地理分布为对比生态位模型和中性模型的预测提供了机会。发现同域分布的隐存物种会增加α多样性并支持中性模型，而异域/邻域分布的隐存物种的记录则会增加β多样性并支持生态位模型。我们利用沿着其2700公里纬度范围的榕小蜂群落的形态学和分子数据，以及环境生态位建模分析，对这些预测进行了检验。分子方法将先前的物种多样性估计从8种增加到11种，在所研究的四个黄蜂属中均揭示出形态上的隐存物种。通过一个关键形态功能性状（产卵器长度）区分的同属物种对在大片区域同域共存。相比之下，具有相似产卵器长度的形态相似物种通常呈现邻域分布范围，重叠很少。尽管是邻域分布范围，但隐存同属物种对的环境生态位模型表明存在大片潜在同域分布区域，这表明竞争过程在决定生态相似物种的分布中很重要。生态位过程似乎构建了这个昆虫群落，并且隐存多样性可能通常主要对β多样性而非α多样性有贡献。
