Intra- and Interspecific Latitudinal Variation in Vertebral Number of Menidia spp. (Teleostei: Atherinopsidae)
Intra- and Interspecific Latitudinal Variation in Vertebral Number of Menidia spp. (Teleostei: Atherinopsidae)
复制标题
梅尼迪亚属椎体数量的种内和种间纬度变异。
作者：
K. Yamahira;T. Lankford;D. Conover
摘要脊椎数是鱼类常用的一个种间鉴别性状，但脊椎数不仅在种间存在差异，而且在种内也存在差异。脊椎动物数量的变化与地理梯度有关，如纬度，它可能反映了环境和遗传对表型的影响。因此，种内和种间的地理变异及其遗传基础的密切相关的物种的比较，不仅有助于有关组的分类，而且还了解这种差异是如何演变的。在这项研究中，我们研究内和种间纬度变化的脊椎数量的两个地理上相邻的，密切相关的物种：大西洋银汉梅尼迪亚menidia（一个北方物种）和潮水银汉M。Peninsulae（南方种）。根据约旦的规则，脊椎数目的野生个体增加与纬度内和物种之间。平均脊椎数变化沿着一个共同的线性轨迹内和种间，可以预测与纬度单独（r = 0.98），表明脊椎数是不是一个诊断性的物种在Menidia字符非常高的精度。共同花园的实验表明，这种纬度渐变在所有温度下都持续存在，表明物种内部和物种之间有着强大的遗传基础。物种在整个地理范围内的连续变化表明，自然选择和适应是最可能的解释，种群和物种可以自由进化每个环境所需的任何脊椎数量。
Abstract Vertebral number is used frequently as a diagnostic species character in fishes, but it varies not only among but also within species. Much of the variation in vertebral number is associated with geographic gradients such as latitude, and it likely reflects both environmental and genetic influences on phenotype. Hence, comparison of intra- and interspecific geographic variation and its genetic basis in closely related species may contribute not only to taxonomy of the group concerned but also to understanding how such differences evolve. In this study, we examine intra- and interspecific latitudinal variation in vertebral number of two geographically contiguous, closely-related species: the Atlantic Silverside Menidia menidia (a northern species) and the Tidewater Silverside M. peninsulae (a southern species). In accordance with Jordan's rule, vertebral numbers of wild individuals increased with latitude within and among species. Mean vertebral number varied along a common linear trajectory both within and among species and could be predicted with very high accuracy from latitude alone (r = 0.98), indicating that vertebral number is not a diagnostic species character in Menidia. Common-garden experiments revealed that this latitudinal cline persists across all temperatures, demonstrating a strong genetic basis within and among species. The continuous variation throughout the entire geographic range across the species suggests that natural selection and adaptation is the most likely explanation, and that populations and species are free to evolve any vertebral number required in each environment.