Brooks George C, Caruso Nicholas M, Chandler Houston C, Haas Carola A
Department of Fish and Wildlife Conservation Virginia Tech Blacksburg Virginia USA.
The Orianne Society Tiger Georgia USA.
Ecol Evol. 2023 Oct 18;13(10):e10629. doi: 10.1002/ece3.10629. eCollection 2023 Oct.
Virtually all natural community assemblages are dominated by a handful of common species. Dominant species can exert negative impacts on biodiversity through competitive exclusion, and thus there is a strong incentive to understand imbalances in community composition, changes in dominance hierarchies through time, and mechanisms of coexistence. Pond-breeding amphibians that utilize ephemeral wetlands provide an excellent opportunity to evaluate theoretical predictions of community composition in stochastic environments. One of the most striking features of pond-breeding amphibians is the marked stochastic fluctuations in abundance across years. Given strong theoretical and empirical links between evenness and biomass, one would expect community evenness to change from year to year. Moreover, if different species exhibit different boom-and-bust reproductive cycles, then a storage effect may help to explain why one species does not outcompete all others. Here, we explore the interplay between biotic and abiotic conditions in shaping amphibian communities at two ephemeral wetlands on Eglin Air Force Base, Florida. We document consistent community composition over 6 years of monitoring, resulting from a lack of species turnover and similar responses of all community members to environmental conditions. The similar dynamics of species argues against a storage effect as the sole mechanism for coexistence and instead points to niche partitioning as a more important factor. In support of this conclusion, we show that the degree of synchrony in breeding migrations only correlates with environmental conditions within species, not between species. The lack of pattern seen between species implies that individuals are somewhat constrained in the timing of breeding migrations, perhaps owing in part to competition with other community members. We hope that our work reinvigorates interest in amphibian communities and highlights ephemeral wetlands as model systems to study community dynamics in stochastic environments.
几乎所有的自然群落组合都由少数常见物种主导。优势物种可通过竞争排斥对生物多样性产生负面影响，因此，人们强烈希望了解群落组成的失衡、优势等级随时间的变化以及共存机制。利用临时性湿地进行繁殖的池塘两栖动物为评估随机环境中群落组成的理论预测提供了绝佳机会。池塘两栖动物最显著的特征之一是其数量年际间存在明显的随机波动。鉴于均匀度与生物量之间存在强大的理论和实证联系，人们预计群落均匀度会逐年变化。此外，如果不同物种表现出不同的兴衰繁殖周期，那么存储效应可能有助于解释为何一个物种不会在竞争中胜过所有其他物种。在此，我们探讨了生物和非生物条件在塑造佛罗里达州埃格林空军基地两个临时性湿地两栖动物群落过程中的相互作用。我们记录了6年监测期内一致的群落组成，这是由于物种更替缺乏以及所有群落成员对环境条件的类似反应所致。物种的相似动态表明，存储效应并非共存的唯一机制，相反，生态位划分是一个更重要的因素。为支持这一结论，我们表明繁殖迁徙的同步程度仅与物种内部的环境条件相关，而非物种之间。物种间缺乏这种模式意味着个体在繁殖迁徙时间上受到一定限制，这可能部分归因于与其他群落成员的竞争。我们希望我们的工作能重新激发人们对两栖动物群落的兴趣，并突出临时性湿地作为研究随机环境中群落动态的模型系统。
