Non-additive effects of intra- and interspecific competition between two larval salamanders

1) Assessment of the relative strengths of intra- and interspecific competition has increased in recent years, and is critical to understanding the importance of competition. Yet, whether intra- and interspecific competition can have non-additive effects has rarely been tested. The resulting fitness consequences of such non-additive interactions are important to provide the context necessary to advance our understanding of competition theory. 2) We compared the strength of additive and non-additive intra- and interspecific competition by manipulating densities of a pair of larval salamanders (Ambystoma talpoideum and A. maculatum) in experimental mesocosms within a response surface design. 3) Intraspecific density had the strongest effect on the strength of competition for both species, and few observed comparisons indicated interspecific competition was an important factor in predicting body size, growth or larval period length of either species. 4) Non-additive effects of intra- ...1) 近年来，针对种内竞争（intraspecific competition）与种间竞争（interspecific competition）相对强度的评估研究愈发受到重视，而厘清二者的相对强度对于理解竞争作用的生态学意义至关重要。然而，种内与种间竞争是否能够产生非加性效应（non-additive effects），迄今鲜有实证检验。这类非加性相互作用所带来的适合度（fitness）后果，可为深化我们对竞争理论的认知提供必要的研究背景。2) 本研究采用响应面设计（response surface design），在中型实验生态系统（experimental mesocosms）中操控两种幼体蝾螈（larval salamanders）——斑点钝口螈（Ambystoma talpoideum）与星点钝口螈（A. maculatum）——的种群密度，对比了加性与非加性种内、种间竞争的强度。3) 对于两个受试物种而言，种内密度对竞争强度的影响最为显著；仅有极少数观测对比结果显示，种间竞争是预测任一物种体型大小、生长速率或幼体期时长的关键因子。4) 种内竞争的非加性效应……