Intraspecific trait variation alters the outcome of competition in freshwater ciliates

Trait variation among heterospecific and conspecific organisms may substantially affect community and food web dynamics. While the relevance of competition and feeding traits have been widely studied for different consumer species, studies on intraspecific differences are more scarce, partly owing to difficulties in distinguishing different clones of the same species. Here, we investigate how intraspecific trait variation affects the competition between the freshwater ciliates Euplotes octocarinatus and Coleps hirtus in a nitrogen-limited chemostat system. The ciliates competed for the microalgae Cryptomonas sp. (Cry) and Navicula pelliculosa (Nav), and the bacteria present in the cultures over a period of 33 days. We used monoclonal Euplotes and three different Coleps clones (Col 1, Col 2, Col 3) in the experiment that could be distinguished by a newly developed rDNA-based molecular assay based on the internal transcribed spacer (ITS) regions. While Euplotes feeds on Cry and on bacteri...异种与同种生物的性状差异可显著影响群落结构与食物网动态。尽管针对不同消费者类群的竞争与取食性状相关性已得到广泛研究，但有关种内性状差异的相关研究仍较为匮乏，这在一定程度上源于难以区分同一物种的不同克隆。本研究旨在探究种内性状变异对氮限制恒化器系统中淡水纤毛虫——八列游仆虫（Euplotes octocarinatus）与赫氏壳袋虫（Coleps hirtus）——种间竞争的影响机制。实验周期为33天，上述两种纤毛虫以培养体系中的微藻隐藻属物种（Cryptomonas sp.，缩写Cry）、薄膜舟形藻（Navicula pelliculosa，缩写Nav）以及共存细菌为竞争食物资源。本实验采用单克隆八列游仆虫与三株不同的赫氏壳袋虫克隆（Col 1、Col 2、Col 3），这些克隆可通过新开发的基于核糖体DNA（ribosomal DNA, rDNA）内部转录间隔区（internal transcribed spacer, ITS）的分子检测技术进行甄别。尽管八列游仆虫可摄食Cry与细菌……