Kharlamova Anastasia V, Trut Lyudmila N, Carrier David R, Chase Kevin, Lark Karl G
Institute of Cytology and Genetics, Siberian Department of Russian Academy of Sciences, Novosibirsk, Russia.
Integr Comp Biol. 2007 Sep;47(3):373-81. doi: 10.1093/icb/icm023.
Genetic variation in functionally integrated skeletal traits can be maintained over 10 million years despite bottlenecks and stringent selection. Here, we describe an analysis of the genetic architecture of the canid axial skeleton using populations of the Portuguese Water Dog Canis familiaris) and silver fox (Vulpes vulpes). Twenty-one skeletal metrics taken from radiographs of the forelimbs and hind limbs of the fox and dog were used to construct separate anatomical principal component (PC) matrices of the two species. In both species, 15 of the 21 PCs exhibited significant heritability, ranging from 25% to 70%. The second PC, in both species, represents a trade-off in which limb-bone width is inversely correlated with limb-bone length. PC2 accounts for approximately 15% of the observed skeletal variation, approximately 30% of the variation in shape. Many of the other significant PCs affect very small amounts of variation (e.g., 0.2-2%) along trade-off axes that partition function between the forelimbs and hind limbs. These PCs represent shape axes in which an increase in size of an element of the forelimb is associated with a decrease in size of an element of the hind limb and vice versa. In most cases, these trade-offs are heritable in both species and genetic loci have been identified in the Portuguese Water Dog for many of these. These PCs, present in both the dog and the fox, include ones that affect lengths of the forelimb versus the hind limb, length of the forefoot versus that of the hind foot, muscle moment (i.e., lever) arms of the forelimb versus hind limb, and cortical thickness of the bones of the forelimb versus hind limb. These inverse relationships suggest that genetic regulation of the axial skeleton results, in part, from the action of genes that influence suites of functionally integrated traits. Their presence in both dogs and foxes suggests that the genes controlling the regulation of these PCs of the forelimb versus hind limb may be found in other tetrapod taxa.
尽管存在瓶颈效应和严格的选择，功能整合的骨骼性状中的遗传变异仍可维持超过1000万年。在此，我们描述了一项利用葡萄牙水犬（Canis familiaris）和银狐（Vulpes vulpes）种群对犬科动物轴向骨骼的遗传结构进行的分析。从狐狸和狗的前肢与后肢X光片中获取的21个骨骼测量指标，被用于构建这两个物种各自独立的解剖主成分（PC）矩阵。在这两个物种中，21个主成分中有15个表现出显著的遗传力，范围从25%到70%。在这两个物种中，第二主成分代表了一种权衡，即肢骨宽度与肢骨长度呈负相关。主成分2约占观察到的骨骼变异的15%，约占形状变异的30%。许多其他显著的主成分沿着在前肢和后肢之间划分功能的权衡轴影响非常少量的变异（例如，0.2 - 2%）。这些主成分代表了形状轴，其中前肢某一元素大小的增加与后肢某一元素大小的减小相关，反之亦然。在大多数情况下，这些权衡在两个物种中都是可遗传的，并且在葡萄牙水犬中已经鉴定出了许多相关的基因座。在狗和狐狸中都存在的这些主成分，包括那些影响前肢与后肢长度、前足与后足长度、前肢与后肢的肌肉力矩（即杠杆）臂以及前肢与后肢骨骼皮质厚度的主成分。这些反向关系表明，轴向骨骼的遗传调控部分源于影响功能整合性状组的基因的作用。它们在狗和狐狸中的存在表明，控制前肢与后肢这些主成分调控的基因可能在其他四足类群中也能找到。
