Nasonia Parasitic Wasps Escape from Haller's Rule by Diphasic, Partially Isometric Brain-Body Size Scaling and Selective Neuropil Adaptations
Nasonia Parasitic Wasps Escape from Haller's Rule by Diphasic, Partially Isometric Brain-Body Size Scaling and Selective Neuropil Adaptations
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DOI：
10.1159/000480421
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发表时间：
2017-01-01
影响因子：
1.7
通讯作者：
Smid, Hans M.
中科院分区：
文献类型：
--
作者：
Groothuis, Jitte;Smid, Hans M.
哈勒的规则指出，在所有动物中，大脑的大小与身体大小呈异速增长，这意味着相对大脑大小随着身体大小的减小而增加。这条规则既适用于种间比较，也适用于种内比较。只有一种，极小的寄生黄蜂赤眼蜂是一个例外，在不同大小的个体之间的种内比较中显示出等长的脑体大小关系。在这里，我们调查了这种等长的脑体大小关系是否也出现在与体型稍大的寄生蜂--玻璃黄蜂的种内比较中，这种寄生蜂的体重可能会随着幼虫发育过程中争夺竞争水平的不同而变化10倍。我们发现，纳斯尼亚表现出脑体大小的双相伸缩：较大的黄蜂按Haller规则异速伸缩，而最小的黄蜂表现出等长伸缩。因此，较小黄蜂的大脑比预期的要小，我们假设这可能会导致大脑结构的适应。对神经毛成分的体积分析表明，不同大小的黄蜂在多个神经毛的相对体积上存在差异。在最小的黄蜂中，视叶和蘑菇体尤其小。此外，较小的大脑比较大的大脑具有相对较小的神经纤维总体积和较大的细胞皮。这些相对大脑大小和大脑结构的变化表明，对脑组织的能量限制超过了小黄蜂的特定认知需求。(C)2017年作者(S)由S.Karger AG，巴塞尔出版
Haller's rule states that brains scale allometrically with body size in all animals, meaning that relative brain size increases with decreasing body size. This rule applies both on inter-and intraspecific comparisons. Only 1 species, the extremely small parasitic wasp Trichogramma evanescens, is known as an exception and shows an isometric brain-body size relation in an intraspecific comparison between differently sized individuals. Here, we investigated if such an isometric brain-body size relationship also occurs in an intraspecific comparison with a slightly larger parasitic wasp, Nasonia vitripennis, a species that may vary 10-fold in body weight upon differences in levels of scramble competition during larval development. We show that Nasonia exhibits diphasic brain-body size scaling: larger wasps scale allometrically, following Haller's rule, whereas the smallest wasps show isometric scaling. Brains of smaller wasps are, therefore, smaller than expected and we hypothesized that this may lead to adaptations in brain architecture. Volumetric analysis of neuropil composition revealed that wasps of different sizes differed in relative volume of multiple neuropils. The optic lobes and mushroom bodies in particular were smaller in the smallest wasps. Furthermore, smaller brains had a relatively smaller total neuropil volume and larger cellular rind than large brains. These changes in relative brain size and brain architecture suggest that the energetic constraints on brain tissue outweigh specific cognitive requirements in small Nasonia wasps. (C) 2017 The Author(s) Published by S. Karger AG, Basel