Meadley Dunphy Shannon A, Prior Kirsten M, Frederickson Megan E
Department of Ecology and Evolutionary Biology, University of Toronto, 25 Harbord Street, Toronto, ON, M5S 3G5, Canada.
Department of Biology, University of Florida, 411 Carr Hall, Gainesville, FL, 32611, USA.
Oecologia. 2016 May;181(1):149-59. doi: 10.1007/s00442-015-3530-0. Epub 2016 Feb 2.
Plant-animal mutualisms, such as seed dispersal, are often vulnerable to disruption by invasive species. Here, we show for the first time how a non-ant invasive species negatively affects seed dispersal by ants. We examined the effects of several animal species that co-occur in a temperate deciduous forest-including native and invasive seed-dispersing ants (Aphaenogaster rudis and Myrmica rubra, respectively), an invasive slug (Arion subfuscus), and native rodents-on a native myrmecochorous plant, Asarum canadense. We experimentally manipulated ant, slug, and rodent access to seed depots and measured seed removal. We also video-recorded depots to determine which other taxa interact with seeds. We found that A. rudis was the main disperser of seeds and that A. subfuscus consumed elaiosomes without dispersing seeds. Rodent visitation was rare, and rodent exclusion had no significant effect on seed or elaiosome removal. We then used data obtained from laboratory and field mesocosm experiments to determine how elaiosome robbing by A. subfuscus affects seed dispersal by A. rudis and M. rubra. We found that elaiosome robbing by slugs reduced seed dispersal by ants, especially in mesocosms with A. rudis, which picks up seeds more slowly than M. rubra. Taken together, our results show that elaiosome robbing by an invasive slug reduces seed dispersal by ants, suggesting that invasive slugs can have profound negative effects on seed dispersal mutualisms.
植物与动物的互利共生关系，如种子传播，常常容易受到入侵物种的干扰。在此，我们首次展示了一种非蚂蚁入侵物种如何对蚂蚁的种子传播产生负面影响。我们研究了在温带落叶林中共同出现的几种动物物种的影响，这些物种包括本地和入侵的种子传播蚂蚁（分别为粗毛弓背蚁和红褐小家蚁）、一种入侵蛞蝓（暗足隆背蛞蝓）以及本地啮齿动物，它们对本地蚁播植物加拿大细辛的影响。我们通过实验控制蚂蚁、蛞蝓和啮齿动物接近种子贮藏点的机会，并测量种子的移除情况。我们还对贮藏点进行了视频记录，以确定哪些其他类群与种子相互作用。我们发现粗毛弓背蚁是种子的主要传播者，而暗足隆背蛞蝓会消耗油质体但不传播种子。啮齿动物的光顾很少见，排除啮齿动物对种子或油质体的移除没有显著影响。然后，我们利用从实验室和野外中型生态系统实验中获得的数据，来确定暗足隆背蛞蝓对油质体的掠夺如何影响粗毛弓背蚁和红褐小家蚁的种子传播。我们发现蛞蝓对油质体的掠夺减少了蚂蚁的种子传播，尤其是在有粗毛弓背蚁的中型生态系统中，粗毛弓背蚁捡起种子的速度比红褐小家蚁慢。综合来看，我们的结果表明，入侵蛞蝓对油质体的掠夺减少了蚂蚁的种子传播，这表明入侵蛞蝓可能对种子传播的互利共生关系产生深远的负面影响。
