Leduc Antoine O H C, Thomas Steven A, Bassar Ronald D, López-Sepulcre Andrés, MacNeill Keeley, El-Sabaawi Rana, Reznick David N, Flecker Alexander S, Travis Joseph
Post-Graduation Program in Ecology, Department of Oceanography and Limnology, Universidade Federal Do Rio Grande Do Norte, Natal, RN, 59014002, Brazil.
Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, 14853, USA.
Oecologia. 2021 Apr;195(4):1053-1069. doi: 10.1007/s00442-021-04884-0. Epub 2021 Mar 18.
The ecological consequences of biological range extensions reflect the interplay between the functional characteristics of the newly arrived species and their recipient ecosystems. Teasing apart the relative contribution of each component is difficult because most colonization events are studied retrospectively, i.e., after a species became established and its consequences apparent. We conducted a prospective experiment to study the ecosystem consequences of a consumer introduction, using whole-stream metabolism as our integrator of ecosystem activity. In four Trinidadian streams, we extended the range of a native fish, the guppy (Poecilia reticulata), by introducing it over barrier waterfalls that historically excluded it from these upper reaches. To assess the context dependence of these range extensions, we thinned the riparian forest canopy on two of these streams to increase benthic algal biomass and productivity. Guppy's range extension into upper stream reaches significantly impacted stream metabolism but the effects depended upon the specific stream into which they had been introduced. Generally, increases in guppy biomass caused an increase in gross primary production (GPP) and community respiration (CR). The effects guppies had on GPP were similar to those induced by increased light level and were larger in strength than the effects stream stage had on CR. These results, combined with results from prior experiments, contribute to our growing understanding of how consumers impact stream ecosystem function when they expand their range into novel habitats. Further study will reveal whether local adaptation, known to occur rapidly in these guppy populations, modifies the ecological consequences of this species introduction.
生物分布范围扩展的生态后果反映了新到达物种的功能特征与其接收生态系统之间的相互作用。区分每个组成部分的相对贡献很困难，因为大多数定殖事件都是事后研究的，也就是说，在一个物种建立并其后果显现之后。我们进行了一项前瞻性实验，以消费者引入为切入点，研究其对生态系统的影响，并将全溪流代谢作为生态系统活动的综合指标。在特立尼达的四条溪流中，我们通过将本地孔雀鱼（孔雀鱼属）引入历史上使其无法进入的上游瀑布来扩大其分布范围。为了评估这些分布范围扩展的背景依赖性，我们对其中两条溪流的河岸林冠层进行了疏伐，以增加底栖藻类生物量和生产力。孔雀鱼向上游的分布范围扩展显著影响了溪流代谢，但其影响取决于引入它们的具体溪流。一般来说，孔雀鱼生物量的增加导致总初级生产力（GPP）和群落呼吸（CR）增加。孔雀鱼对GPP的影响与光照水平增加所引发的影响相似，且强度大于溪流阶段对CR的影响。这些结果，结合之前实验的结果，有助于我们进一步了解消费者在扩展到新栖息地时如何影响溪流生态系统功能。进一步的研究将揭示，已知在这些孔雀鱼种群中迅速发生的局部适应性是否会改变该物种引入的生态后果。
