Complex Craniofacial Changes in Blind Cave-Dwelling Fish Are Mediated by Genetically Symmetric and Asymmetric Loci
Complex Craniofacial Changes in Blind Cave-Dwelling Fish Are Mediated by Genetically Symmetric and Asymmetric Loci
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DOI：
10.1534/genetics.114.161661
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发表时间：
2014-04-01
期刊：
影响因子：
3.3
通讯作者：
Carlson, Brian M.
中科院分区：
文献类型：
--
作者：
Gross, Joshua B.;Krutzler, Amanda J.;Carlson, Brian M.
退化颅面形态的遗传调节因子知之甚少。为了阐明这个问题，我们研究了淡水鱼Astyanax mexicanus，一种具有表面居住和多个独立的无眼洞穴居住形式的物种。影响洞穴鱼头骨的变化包括环绕眼睛的膜内眶周骨的形态学改变。然而，这些改变中的许多已经与眼睛丧失分开发展，例如第三眶下骨的碎裂。为了了解这些眼睛独立的颅面改变的遗传结构，我们开发和评分33表型的背景下，从Pachon洞穴鱼和表面鱼繁殖的F-2杂交映射系谱。我们发现几个个体在骨形成方面表现出巨大的左右差异，例如仅在右侧出现广泛的碎片。这一观察结果，沿着众所周知的眼睛大小不对称的自然穴居动物，使我们进一步评估左右遗传差异的颅面复合体。我们发现了三种表型，包括骨碎裂和融合，这表明了一个方向的遗传基础，只有一边。有趣的是，受影响的骨骼的整体区域在遗传上是对称的。这些新的颅面QTL的表型效应图显示，洞穴等位基因与异常的条件，如骨融合和碎片。此外，许多连锁位点与其他洞穴相关的特征重叠，这表明回归颅面的变化可能会通过连锁或作为拮抗多效性的洞穴相关的适应性的后果。这些新的发现阐明了在完全黑暗中伴随进化而来的显著颅面变化，并揭示了头骨的复杂变化，这些变化受到影响左右两侧的遗传变化的不同影响。
The genetic regulators of regressive craniofacial morphologies are poorly understood. To shed light on this problem, we examined the freshwater fish Astyanax mexicanus, a species with surface-dwelling and multiple independent eyeless cave-dwelling forms. Changes affecting the skull in cavefish include morphological alterations to the intramembranous circumorbital bones encircling the eye. Many of these modifications, however, have evolved separately from eye loss, such as fragmentation of the third suborbital bone. To understand the genetic architecture of these eye-independent craniofacial alterations, we developed and scored 33 phenotypes in the context of an F-2 hybrid mapping pedigree bred from Pachon cavefish and surface fish. We discovered several individuals exhibiting dramatic left-right differences in bone formation, such as extensive fragmentation on the right side only. This observation, along with well-known eye size asymmetry in natural cave-dwelling animals, led us to further evaluate left-right genetic differences for the craniofacial complex. We discovered three phenotypes, inclusive of bone fragmentation and fusion, which demonstrated a directional heritable basis only on one side. Interestingly, the overall areas of affected bones were genetically symmetric. Phenotypic effect plots of these novel craniofacial QTL revealed that cave alleles are associated with abnormal conditions such as bony fusion and fragmentation. Moreover, many linked loci overlapped with other cave-associated traits, suggesting regressive craniofacial changes may evolve through linkage or as antagonistic pleiotropic consequences of cave-associated adaptations. These novel findings illuminate significant craniofacial changes accompanying evolution in complete darkness and reveal complex changes to the skull differentially influenced by genetic changes affecting the left and right sides.