Powell George Lawrence, Russell Anthony P, Sutey Jennifer
Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada.
J Morphol. 2018 Aug;279(8):1088-1103. doi: 10.1002/jmor.20833. Epub 2018 May 6.
Postnatal growth patterns within the vertebral column may be informative about body proportions and regionalization. We measured femur length, lengths of all pre-sacral vertebrae, and lengths of intervertebral spaces, from radiographs of a series of 21 Eublepharis macularius, raised under standard conditions and covering most of the ontogenetic body size range. Vertebrae were grouped into cervical, sternal, and dorsal compartments, and lengths of adjacent pairs of vertebrae were summed before analysis. Femur length was included as an index of body size. Principal component analysis of the variance-covariance matrix of these data was used to investigate scaling among them. PC1 explained 94.19% of total variance, interpreted as the variance due to body size. PC1 differed significantly from the hypothetical isometric vector, indicating overall allometry. The atlas and axis vertebrae displayed strong negative allometry; the remainder of the vertebral pairs exhibited weak negative allometry, isometry or positive allometry. PC1 explained a markedly smaller amount of variance for the vertebral pairs of the cervical compartment than for the remainder of the vertebral pairs, with the exception of the final pair. The relative standard deviations of the eigenvalues from the PCAs of the three vertebral compartments indicated that the vertebrae of the cervical compartment were less strongly integrated by scaling than were the sternal or dorsal vertebrae, which did not differ greatly between themselves in their strong integration, suggesting that the growth of the cervical vertebrae is constrained by the mechanical requirements of the head. Regionalization of the remainder of the vertebral column is less clearly defined but may be associated with wave form propagation incident upon locomotion, and by locomotory changes occasioned by tail autotomy and regeneration. Femur length exhibits negative allometry relative to individual vertebral pairs and to vertebral column length, suggesting a change in locomotor requirements over the ontogenetic size range.
脊柱的产后生长模式可能有助于了解身体比例和区域划分。我们从21只在标准条件下饲养、涵盖了大部分个体发育体型范围的黄斑睑虎的X光片中，测量了股骨长度、所有骶前椎骨的长度以及椎间隙的长度。椎骨被分为颈椎、胸骨和背椎部分，在分析前将相邻椎骨对的长度相加。股骨长度作为体型指标纳入分析。对这些数据的方差协方差矩阵进行主成分分析，以研究它们之间的缩放关系。主成分1（PC1）解释了总方差的94.19%，被解释为体型引起的方差。PC1与假设的等距向量有显著差异，表明整体异速生长。寰椎和枢椎显示出强烈的负异速生长；其余椎骨对表现出较弱的负异速生长、等速生长或正异速生长。PC1对颈椎部分椎骨对的方差解释量明显小于对其余椎骨对的方差解释量，但最后一对椎骨除外。三个椎骨部分主成分分析的特征值相对标准差表明，颈椎部分的椎骨在缩放整合上不如胸骨或背椎强烈，胸骨和背椎在强烈整合方面彼此差异不大，这表明颈椎的生长受到头部机械需求的限制。脊柱其余部分的区域划分不太明确，但可能与运动时的波形传播以及尾部自切和再生引起的运动变化有关。股骨长度相对于单个椎骨对和脊柱长度表现出负异速生长，表明在个体发育体型范围内运动需求发生了变化。
