Undergraduate Program in Neuroscience, Boston University, , 2 Cummington Mall, Boston, MA 02215, USA, Department of Neuroscience, University of Arizona, , 611 Gould-Simpson Science Building, Tucson, AZ 85721, USA, Department of Science and Education, Field Museum of Natural History, , 1400 South Lake Shore Drive, Chicago, IL 60605, USA, Department of Biology, Boston University, , 5 Cummington Mall, Boston, MA 02215, USA.
Proc Biol Sci. 2014 Apr 16;281(1784):20140217. doi: 10.1098/rspb.2014.0217. Print 2014 Jun 7.
The extent to which size constrains the evolution of brain organization and the genesis of complex behaviour is a central, unanswered question in evolutionary neuroscience. Advanced cognition has long been linked to the expansion of specific brain compartments, such as the neocortex in vertebrates and the mushroom bodies in insects. Scaling constraints that limit the size of these brain regions in small animals may therefore be particularly significant to behavioural evolution. Recent findings from studies of paper wasps suggest miniaturization constrains the size of central sensory processing brain centres (mushroom body calyces) in favour of peripheral, sensory input centres (antennal and optic lobes). We tested the generality of this hypothesis in diverse eusocial hymenopteran species (ants, bees and wasps) exhibiting striking variation in body size and thus brain size. Combining multiple neuroanatomical datasets from these three taxa, we found no universal size constraint on brain organization within or among species. In fact, small-bodied ants with miniscule brains had mushroom body calyces proportionally as large as or larger than those of wasps and bees with brains orders of magnitude larger. Our comparative analyses suggest that brain organization in ants is shaped more by natural selection imposed by visual demands than intrinsic design limitations.
体型在多大程度上限制了大脑组织的进化和复杂行为的产生，这是进化神经科学中的一个核心问题，尚未得到解答。高级认知能力长期以来一直与特定脑区的扩张有关，例如脊椎动物的新皮层和昆虫的蘑菇体。因此，体型限制对小动物的这些脑区的大小限制可能对行为进化特别重要。最近对纸蜂的研究结果表明，小型化有利于外周感觉输入中心（触角和视神经叶），而不是中央感觉处理脑中心（蘑菇体果瓣）。我们在表现出显著体型和脑型差异的多种社会性膜翅目昆虫（蚂蚁、蜜蜂和黄蜂）物种中测试了这一假说的普遍性。我们结合了这三个分类群的多个神经解剖数据集，发现物种内或物种间的大脑组织没有普遍的体型限制。事实上，体型较小的蚂蚁，其大脑非常小，但蘑菇体果瓣的比例与体型大得多、脑容量大几个数量级的黄蜂和蜜蜂的蘑菇体果瓣一样大，或者更大。我们的比较分析表明，蚂蚁的大脑组织更多地受到视觉需求施加的自然选择的影响，而不是受到内在设计限制的影响。
