Hooker Oliver E, Van Leeuwen Travis E, Adams Colin E
Scottish Centre for Ecology and the Natural Environment, IBAHCM, University of Glasgow, Rowardennan, Loch Lomond, Glasgow, G63 0AW, UK.
PR Statistics, 3/1, 128 Brunswick Street, Glasgow, G1 1TF, UK.
J Anim Ecol. 2017 May;86(3):605-614. doi: 10.1111/1365-2656.12632. Epub 2017 Mar 1.
Sympatric speciation is thought to be strongly linked to resource specialization with alternative resource use acting as a fundamental agent driving divergence. However, sympatric speciation through niche expansion is dependent on foraging specialization being consistent over space and time. Standard metabolic rate is the minimal maintenance metabolic rate of an ectotherm in a post-absorptive and inactive state and can constitute a significant portion of an animal's energy budget; thus, standard metabolic rate and growth rate are two measures frequently used as an indication of the physiological performance of individuals. Physiological adaptations to a specific diet may increase the efficiency with which it is utilized, but may have an increased cost associated with switching diets, which may result in a reduced standard metabolic rate and growth rate. In this study, we use the diet specialization often seen in polymorphic Arctic charr (Salvelinus alpinus) populations to study the effects of different prey on standard metabolic rate and growth rate as well as the effects that early prey specialization may have on the ability to process other prey types efficiently. We found a significant effect of prey type on standard metabolic rate and growth rate. Furthermore, we found evidence of diet specialization with all fish maintaining a standard metabolic rate and growth rate lower than expected when fed on a diet different to which they were raised, possibly due to a maladaptation in digestion of alternative prey items. Our results show that early diet specialization may be reinforced by the elevated costs of prey switching, thus promoting the process of resource specialization during the incipient stages of sympatric divergence.
同域物种形成被认为与资源专业化密切相关，替代性资源利用作为驱动分化的基本因素。然而，通过生态位扩张实现的同域物种形成取决于觅食专业化在空间和时间上的一致性。标准代谢率是变温动物在吸收后和不活动状态下的最低维持代谢率，可占动物能量预算的很大一部分；因此，标准代谢率和生长率是经常用于指示个体生理性能的两个指标。对特定饮食的生理适应可能会提高其利用效率，但改变饮食可能会增加成本，这可能导致标准代谢率和生长率降低。在本研究中，我们利用多态北极红点鲑（Salvelinus alpinus）种群中常见的饮食专业化来研究不同猎物对标准代谢率和生长率的影响，以及早期猎物专业化对有效处理其他猎物类型能力的影响。我们发现猎物类型对标准代谢率和生长率有显著影响。此外，我们发现了饮食专业化的证据，所有鱼类在喂食与其生长时不同的饮食时，其标准代谢率和生长率均低于预期，这可能是由于对替代猎物的消化适应不良所致。我们的结果表明，早期饮食专业化可能会因猎物转换成本的增加而得到加强，从而在同域分化的初始阶段促进资源专业化进程。
