Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, Santa Barbara, California, USA.
Ecology. 2022 Jul;103(7):e3693. doi: 10.1002/ecy.3693. Epub 2022 May 23.
Acquired phototrophs, organisms that obtain their photosynthetic abilities by hosting endosymbionts or stealing plastids from their prey, are omnipresent in aquatic ecosystems. This acquisition of photosynthetic metabolism allows for niche expansion, and can therefore influence competition outcomes by alleviating competition for shared resources. Here, we test how acquired metabolism alters competitive outcomes by manipulating light availability to control the energetic contribution of photosynthesis to acquired phototrophs. Using freshwater protists that compete for bacterial prey, we demonstrate light-dependent competition outcomes of acquired phototrophs (Paramecium bursaria) and strict heterotrophs (Colpidium sp.) in laboratory model experiments. We then synthesize these findings using a series of mathematical models, and show that explicitly accounting for resource competition improves model fits. Both empirical and mathematical models predict that the acquired phototroph should increase in competitive dominance with increasing light availability. Our results highlight the importance of acquired metabolism to community dynamics, highlighting the need for more empirical and theoretical studies of this mechanism for niche expansion.
获得光合作用能力的生物，通过内共生体或从猎物中窃取质体来获得光合作用能力，在水生生态系统中无处不在。这种获取光合作用代谢的能力可以扩大生态位，从而通过缓解对共享资源的竞争来影响竞争结果。在这里，我们通过操纵光照来控制光合作用对获得光合作用能力的生物的能量贡献，从而测试获得的新陈代谢如何改变竞争结果。我们使用竞争细菌猎物的淡水原生动物，在实验室模型实验中证明了获得光合作用能力的生物（Paramecium bursaria）和严格异养生物（Colpidium sp.）的光依赖性竞争结果。然后，我们使用一系列数学模型综合这些发现，并表明明确考虑资源竞争可以提高模型拟合度。实证和数学模型都预测，随着光照的增加，获得光合作用能力的生物的竞争优势应该会增加。我们的研究结果强调了获得光合作用能力对群落动态的重要性，突出了需要更多的经验和理论研究来了解这种扩大生态位的机制。
