Geographic variation in morphology in the Mohave Rattlesnake (Crotalus scutulatus Kennicott 1861) (Serpentes: Viperidae): implications for species boundaries
Geographic variation in morphology in the Mohave Rattlesnake (Crotalus scutulatus Kennicott 1861) (Serpentes: Viperidae): implications for species boundaries
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莫哈维响尾蛇 (Crotalus scutulatus Kennicott 1861)（蛇类：蝰蛇科）形态的地理变异：对物种边界的影响
DOI：
10.11646/zootaxa.4683.1.7
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发表时间：
2019
期刊：
影响因子：
0.9
通讯作者：
MEIK, JESSE M.
中科院分区：
文献类型：
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作者：
WATSON, JESSICA A.;SPENCER, CAROL L.;SCHIELD, DREW R.;BUTLER, BRETT O.;SMITH, LYDIA L.;FLORES-VILLELA, OSCAR;CAMPBELL, JONATHAN A.;MACKESSY, STEPHEN P.;CASTOE, TODD A.;MEIK, JESSE M.
莫哈维响尾蛇（Crotalus scutulatus）是一种剧毒的蛇，生活在北美西部干旱的沙漠、草原和稀树大草原上。目前已知的两个亚种是北莫哈韦响尾蛇（C. s. scuculatus），分布在加利福尼亚南部到墨西哥中部高原南部，以及墨西哥中南部的特拉斯卡拉、韦拉克鲁斯和普埃布拉地区的瓦曼特拉响尾蛇（C. s. salvini）。尽管最近的研究表明，该物种在毒液成分和隐遗传多样性方面存在广泛的地理差异，但没有现代研究关注形态的地理差异。本文分析了347个石竹标本的定性、分生和形态特征，结果表明石竹在表型上具有内聚性，没有离散的亚群，其主要颜色模式和分生特征在其广阔分布的主要轴上呈连续的渐变。在先前发表的分子证据的背景下，我们的形态学分析表明，更新世期间元种群之间的多次隔离和二次接触足以产生独特的遗传种群，这些遗传种群经历了基因流动，产生了表型的临床变异，而这些原始种群之间没有离散或可诊断的差异。从分类学的角度来看，我们建议将C. s. scuculatus作为一个单独的物种保留下来，尽管在形态上最独特的种群C. s. salvini可能是物种形成初期的外围分离物。
The Mohave Rattlesnake (Crotalus scutulatus) is a highly venomous pitviper inhabiting the arid interior deserts, grasslands, and savannas of western North America. Currently two subspecies are recognized: the Northern Mohave Rattlesnake (C. s. scutulatus) ranging from southern California to the southern Central Mexican Plateau, and the Huamantla Rattlesnake (C. s. salvini) from the region of Tlaxcala, Veracruz, and Puebla in south-central Mexico. Although recent studies have demonstrated extensive geographic variation in venom composition and cryptic genetic diversity in this species, no modern studies have focused on geographic variation in morphology. Here we analyzed a series of qualitative, meristic, and morphometric traits from 347 specimens of C. scutulatus and show that this species is phenotypically cohesive without discrete subgroups, and that morphology follows a continuous cline in primarily color pattern and meristic traits across the major axis of its expansive distribution. Interpreted in the context of previously published molecular evidence, our morphological analyses suggest that multiple episodes of isolation and secondary contact among metapopulations during the Pleistocene were sufficient to produce distinctive genetic populations, which have since experienced gene flow to produce clinal variation in phenotypes without discrete or diagnosable distinctions among these original populations. For taxonomic purposes, we recommend that C. scutulatus be retained as a single species, although it is possible that C. s. salvini, which is morphologically the most distinctive population, could represent a peripheral isolate in the initial stages of speciation.