Aquatic beetles influence colonization of disparate taxa in small lentic systems

Structure of natural communities is shaped by both abiotic characteristics and by the ongoing processes of community assembly. Important to this process are the habitat selection behaviors and subsequent survival of colonists, both in the context of temporal changes in the abiotic characteristics and priority effects driven by earlier colonists. Aquatic beetles are prevalent in temporary freshwater systems, form speciose assemblages, and are often early colonists of temporary ponds. While beetles have the potential to influence community structure through post-colonization interactions (predation and competition), our goal was to determine whether the presence of beetle assemblages (versus patches without beetles) influence the colonization and oviposition of a diverse group of animals in a naturally-colonized experimental landscape. We established mesocosms that either contained existing beetle assemblages or contained no beetles and assessed abundances of subsequent colonists. Treefrogs, Hyla chrysoscelis, and mosquitoes, Culex restuans, both deposited fewer eggs in patches containing beetle assemblages, while two beetles, Copelatus glyphicus and Paracymus, colonized those patches at lower rates. One beetle, Helophorus linearis, colonized patches containing beetle assemblages at higher rates, while two beetles, Berosus infuscatus and Tropisternus lateralis, exhibited no colonization differences between treatments. Overall, there were no differences in the assemblage structure or richness of beetles that colonized patches. Our results illustrate the importance of species-specific habitat selection behavior in determining the species composition of habitat patches, while emphasizing the role of priority effects in influencing patterns of community assembly. Habitat selection in response to abiotic and biotic characteristics of habitat patches can potentially create greater spatiotemporal niche separation among the numerous, often closely-related species (phylogenetically and trophically), that can be simultaneously found in similar patches across landscapes. Methods Data are sums across entire duration of experiment.自然群落的结构同时受非生物特征（abiotic characteristics）与持续进行的群落组装过程共同塑造。该过程的核心环节包括拓殖者的栖息地选择行为及后续存活，二者均需结合非生物特征的时间动态与早期拓殖者介导的优先效应（priority effects）进行分析。水生甲虫在临时淡水生境中分布广泛，可形成物种丰富的群落，且往往是临时池塘的早期拓殖类群。尽管甲虫可通过拓殖后相互作用（post-colonization interactions，捕食与竞争）对群落结构产生影响，但本研究旨在明确：在自然拓殖的实验景观（naturally-colonized experimental landscape）中，甲虫群落的存在与否（相较于无甲虫的生境斑块）是否会影响多样类群动物的拓殖与产卵（oviposition）行为。 我们设置了两类中型实验生态系统（mesocosms）：一类包含已定植的甲虫群落，另一类无甲虫，并评估了后续拓殖者的丰度。结果显示，灰树蛙（Hyla chrysoscelis）与扰库蚊（Culex restuans）均在含有甲虫群落的斑块中产卵量更少；而两种甲虫——Copelatus glyphicus与Paracymus属物种——在这类斑块中的拓殖率更低。另有甲虫Helophorus linearis，在含甲虫群落的斑块中拓殖率更高；其余两种甲虫Berosus infuscatus与Tropisternus lateralis，在两种处理间的拓殖率无显著差异。整体而言，拓殖至各斑块的甲虫群落在群落结构与物种丰富度上均无显著差异。 本研究结果阐明了物种特异性栖息地选择行为在决定生境斑块物种组成中的关键作用，同时强调了优先效应在调控群落组装模式中的意义。针对生境斑块非生物与生物特征的栖息地选择行为，可潜在提升景观中相似斑块内众多（通常为近缘的）物种在系统发育与营养生态位上的时空分离程度。 方法 数据为整个实验周期内的总和。