Kotrschal Alexander, Corral-Lopez Alberto, Szidat Sönke, Kolm Niclas
Department of Ethology/Zoology, Stockholm University, Sweden.
Department of Chemistry and Biochemistry, University of Bern, Switzerland.
Evolution. 2015 Nov;69(11):3013-20. doi: 10.1111/evo.12784. Epub 2015 Oct 19.
One key hypothesis in the study of brain size evolution is the expensive tissue hypothesis; the idea that increased investment into the brain should be compensated by decreased investment into other costly organs, for instance the gut. Although the hypothesis is supported by both comparative and experimental evidence, little is known about the potential changes in energetic requirements or digestive traits following such evolutionary shifts in brain and gut size. Organisms may meet the greater metabolic requirements of larger brains despite smaller guts via increased food intake or better digestion. But increased investment in the brain may also hamper somatic growth. To test these hypotheses we here used guppy (Poecilia reticulata) brain size selection lines with a pronounced negative association between brain and gut size and investigated feeding propensity, digestive efficiency (DE), and juvenile growth rate. We did not find any difference in feeding propensity or DE between large- and small-brained individuals. Instead, we found that large-brained females had slower growth during the first 10 weeks after birth. Our study provides experimental support that investment into larger brains at the expense of gut tissue carries costs that are not necessarily compensated by a more efficient digestive system.
脑容量进化研究中的一个关键假设是昂贵组织假设；该观点认为，对大脑投入的增加应由对其他昂贵器官（如肠道）投入的减少来补偿。尽管这一假设得到了比较证据和实验证据的支持，但对于大脑和肠道大小发生这种进化变化后能量需求或消化特征的潜在变化，我们却知之甚少。尽管肠道变小，但生物体可能通过增加食物摄入量或更好的消化来满足更大脑容量带来的更高代谢需求。但是，对大脑投入的增加也可能会阻碍身体生长。为了验证这些假设，我们在这里使用了孔雀鱼（孔雀鱼）脑容量选择品系，其大脑和肠道大小之间存在明显的负相关，并研究了摄食倾向、消化效率（DE）和幼鱼生长率。我们没有发现大脑袋和小脑袋个体在摄食倾向或消化效率上有任何差异。相反，我们发现大脑袋雌性在出生后的前10周生长较慢。我们的研究提供了实验支持，即牺牲肠道组织来增加对大脑的投入会带来成本，而更高效的消化系统不一定能弥补这些成本。
