Earth and Life Institute, Biodiversity Research Centre, Université Catholique de Louvain, 1348 Louvain-la-Neuve, Belgium;
Station d'Ecologie Théorique et Expérimentale (UMR5321), CNRS, Université Paul Sabatier, F-09200 Moulis, France.
Proc Natl Acad Sci U S A. 2018 Nov 20;115(47):11988-11993. doi: 10.1073/pnas.1805574115. Epub 2018 Nov 5.
Limited dispersal is classically considered as a prerequisite for ecological specialization to evolve, such that generalists are expected to show greater dispersal propensity compared with specialists. However, when individuals choose habitats that maximize their performance instead of dispersing randomly, theory predicts dispersal with habitat choice to evolve in specialists, while generalists should disperse more randomly. We tested whether habitat choice is associated with thermal niche specialization using microcosms of the ciliate , a species that performs active dispersal. We found that thermal specialists preferred optimal habitats as predicted by theory, a link that should make specialists more likely to track suitable conditions under environmental changes than expected under the random dispersal assumption. Surprisingly, generalists also performed habitat choice but with a preference for suboptimal habitats. Since this result challenges current theory, we developed a metapopulation model to understand under which circumstances such a preference for suboptimal habitats should evolve. We showed that competition between generalists and specialists may favor a preference for niche margins in generalists under environmental variability. Our results demonstrate that the behavioral dimension of dispersal-here, habitat choice-fundamentally alters our predictions of how dispersal evolve with niche specialization, making dispersal behaviors crucial for ecological forecasting facing environmental changes.
局限性扩散通常被认为是生态特化进化的前提条件,因此与专家相比,通才预计会表现出更大的扩散倾向。然而,当个体选择能够最大程度地提高其表现的栖息地而不是随机扩散时,理论预测专家会随着栖息地选择而进化扩散,而通才应该更随机地扩散。我们使用纤毛虫的微宇宙来测试栖息地选择是否与热生态位特化有关,纤毛虫是一种进行主动扩散的生物。我们发现,热专家如理论所预测的那样,更喜欢最佳栖息地,这种联系应该使专家比在随机扩散假设下更有可能在环境变化下跟踪合适的条件。令人惊讶的是,通才也进行了栖息地选择,但更喜欢次优栖息地。由于这一结果挑战了当前的理论,我们开发了一个复合种群模型来了解在何种情况下,这种对次优栖息地的偏好应该进化。我们表明,在环境变异性下,通才和专家之间的竞争可能有利于通才对生态位边缘的偏好。我们的研究结果表明,扩散的行为维度——这里是栖息地选择——从根本上改变了我们对扩散如何随着生态位特化而进化的预测,使扩散行为成为面对环境变化进行生态预测的关键。