Mooney Emily H, Phillips Joseph S, Tillberg Chadwick V, Sandrow Cheryl, Nelson Annika S, Mooney Kailen A
Department of Biology, University of Colorado at Colorado Springs, 1420 Austin Bluffs Parkway, Colorado Springs, CO, USA.
Rocky Mountain Biological Laboratory, PO Box 319, Crested Butte, CO, 81224.
Ecol Lett. 2016 Jan;19(1):37-44. doi: 10.1111/ele.12540. Epub 2015 Nov 13.
Species abundance is typically determined by the abiotic environment, but the extent to which such effects occur through the mediation of biotic interactions, including mutualisms, is unknown. We explored how light environment (open meadow vs. shaded understory) mediates the abundance and ant tending of the aphid Aphis helianthi feeding on the herb Ligusticum porteri. Yearly surveys consistently found aphids to be more than 17-fold more abundant on open meadow plants than on shaded understory plants. Manipulations demonstrated that this abundance pattern was not due to the direct effects of light environment on aphid performance, or indirectly through host plant quality or the effects of predators. Instead, open meadows had higher ant abundance and per capita rates of aphid tending and, accordingly, ants increased aphid population growth in meadow but not understory environments. The abiotic environment thus drives the abundance of this herbivore exclusively through the mediation of a protection mutualism.
物种丰富度通常由非生物环境决定，但这种影响通过包括互利共生在内的生物相互作用进行调节的程度尚不清楚。我们探究了光照环境（开阔草地与林下荫蔽处）如何调节以草本植物波特川芎为食的蚜虫——向日葵蚜的数量以及蚂蚁对其的照料行为。年度调查始终发现，开阔草地上的蚜虫数量比林下荫蔽处植物上的蚜虫数量多17倍以上。实验表明，这种数量模式并非由于光照环境对蚜虫表现的直接影响，也不是通过寄主植物质量或捕食者的影响间接产生的。相反，开阔草地的蚂蚁数量更多，且对蚜虫的人均照料率更高，因此，蚂蚁促进了开阔草地环境中蚜虫种群的增长，而在林下荫蔽处环境中则不然。因此，非生物环境仅通过一种保护互利共生关系来驱动这种食草动物的数量。
