Department of Botany and Zoology, Masaryk University, Kotlářská 267/2, 611 37, Brno, Czech Republic.
Institute of Vertebrate Biology, Czech Academy of Sciences, Květná 8, 60365, Brno, Czech Republic.
Sci Rep. 2017 Jul 12;7(1):5177. doi: 10.1038/s41598-017-05485-9.
The energy costs of self-maintenance (standard metabolic rate, SMR) vary substantially among individuals within a population. Despite the importance of SMR for understanding life history strategies, ecological sources of SMR variation remain only partially understood. Stress-mediated increases in SMR are common in subordinate individuals within a population, while the direction and magnitude of the SMR shift induced by interspecific competitive interactions is largely unknown. Using laboratory experiments, we examined the influence of con- and heterospecific pairing on SMR, spontaneous activity, and somatic growth rates in the sympatrically living juvenile newts Ichthyosaura alpestris and Lissotriton vulgaris. The experimental pairing had little influence on SMR and growth rates in the smaller species, L. vulgaris. Individuals exposed to con- and heterospecific interactions were more active than individually reared newts. In the larger species, I. alpestris, heterospecific interactions induced SMR to increase beyond values of individually reared counterparts. Individuals from heterospecific pairs and larger conspecifics grew faster than did newts in other groups. The plastic shift in SMR was independent of the variation in growth rate and activity level. These results reveal a new source of individual SMR variation and potential costs of co-occurrence in ecologically similar taxa.
个体自我维持的能量成本（标准代谢率，SMR）在种群内个体之间存在很大差异。尽管 SMR 对于理解生活史策略很重要，但 SMR 变化的生态来源仍未完全理解。在种群中处于从属地位的个体中，SMR 因压力而增加的情况很常见，而种间竞争相互作用引起的 SMR 变化的方向和幅度在很大程度上是未知的。我们使用实验室实验研究了同种和异种配对对共生的幼体蝾螈 Ichthyosaura alpestris 和 Lissotriton vulgaris 的 SMR、自发活动和体生长率的影响。在较小的物种 L. vulgaris 中，实验配对对 SMR 和生长率的影响很小。与单独饲养的蝾螈相比，暴露于同种和异种相互作用的个体更活跃。在较大的物种 I. alpestris 中，异种相互作用导致 SMR 增加，超过了单独饲养的对应物的值。来自异种配对和较大同种的个体比其他组的蝾螈生长得更快。SMR 的这种可塑变化与生长率和活动水平的变化无关。这些结果揭示了个体 SMR 变化的新来源和在生态相似类群中共同出现的潜在成本。
