Phenotypic diversity is the cornerstone of evolution: Variation in cortical field size within short-tailed opossums
Phenotypic diversity is the cornerstone of evolution: Variation in cortical field size within short-tailed opossums
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DOI：
10.1002/cne.21156
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发表时间：
2006-12-20
影响因子：
2.5
通讯作者：
Krubitzer, Leah
中科院分区：
文献类型：
--
作者：
Karlen, Sarah J.;Krubitzer, Leah
自然选择对群体内存在的表型变异起作用。皮质组织的可变方面，例如皮质区域的大小和连接，可以产生行为差异，这是自然选择的目标。然而，有关皮质组织的物种内变异性的研究仍然有限。在本研究中，我们研究了成年短尾负鼠（Monodelphis Domestica）的大脑尺寸、皮质层尺寸和初级感觉皮质区域尺寸的变化。在个体中，我们发现左右半球的背外侧皮层的整体大小或初级皮层区域的大小没有显着差异。在个体之间，我们发现脑重量、脑体积以及背外侧新皮质和梨状皮质的皮质片面积的种内差异相对较小；然而，我们观察到体重和初级感觉皮层大小（由骨髓结构定义）存在很大程度的变异性。此外，我们发现每个皮质区域的大小与其他皮质区域的大小以及背外侧皮质的总大小相关。在这里，我们讨论变异的可能来源，并检查皮层区域大小与跨物种的感觉处理能力和行为之间的关系。由于行为是自然选择的目标，个体之间皮层区域大小的差异可能为皮层区域进化提供必要的原材料。
Natural selection operates on phenotypic variation that exists within a population. Variable aspects of cortical organization, such as the size and connections of a cortical field, can generate differences in behavior, which is a target of natural selection. Yet studies pertaining to within-species variability in cortical organization are limited. In the present investigation, we examined variation in brain size, cortical sheet size, and primary sensory cortical field sizes in the adult short-tailed opossum (Monodelphis domestica). Within individuals, we found no significant difference between the right and left hemispheres in the overall size of the dorsolateral cortex or in primary cortical field sizes. Between individuals, we found relatively little intraspecies variation in brain weight, brain volume, and cortical sheet area for the dorsolateral neocortex and pyriform cortex; however, we observed a large degree of variability in body weight and primary sensory cortical field size, as defined by myeloarchitecture. Further, we found that the size of each cortical field correlated with the size of the other cortical fields as well as with the total size of the dorsolateral cortex. Here we discuss the possible sources of variation and examine the relationship between cortical field size and sensory processing abilities and behaviors across species. Since behavior is the target of natural selection, variation in cortical field size across individuals may supply the raw material necessary for cortical field evolution.