The road not taken: Evolution of tetrodotoxin resistance in the Sierra garter snake (Thamnophis couchii) by a path less travelled.
The road not taken: Evolution of tetrodotoxin resistance in the Sierra garter snake (Thamnophis couchii) by a path less travelled.
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未走的路：塞拉袜带蛇（Thamnophis couchii）的河豚毒素抗性沿着一条少有人走的路进化。
DOI：
10.1111/mec.16538
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发表时间：
2022
影响因子：
4.9
通讯作者：
Feldman,ChrisR
中科院分区：
文献类型：
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作者：
Reimche,JessicaS;DelCarlo,RobertE;BrodieJr,EdmundD;McGlothlin,JoelW;Schlauch,Karen;Pfrender,MichaelE;Brodie3rd,EdmundD;Leblanc,Normand;Feldman,ChrisR
河豚毒素（TTX）抗性的重复进化为检验趋同进化机制的假说提供了一个模型。这种毒素被广泛用作一种有效的抗捕食者防御，阻断肌肉和神经中的电压门控钠通道（Nav），麻痹甚至杀死捕食者。耐药的类群轴承这种神经毒素和一些捕食者似乎来自收敛更换特定的Navresidues与TTX相互作用。这种刻板的遗传反应表明，分子和表型进化可能是受约束和可预测的。在这里，我们调查的机械收敛的程度束带蛇（Thamnophis）捕食TTX-轴承蝾螈（Taricha）通过检查TTX抗性的生理和遗传基础在塞拉利昂束带蛇（Th. couchii）。我们在几个生物尺度上描述了这种捕食性适应在种群间的变化：全动物TTX抗性;骨骼肌抗性;三个Navencoding基因座的功能遗传变异;以及其中一个基因座的基因表达水平。我们发现，在整个动物和骨骼肌水平上，库奇氏杆菌的抗性具有广泛的地理差异。与其他Thamnophis一样，这两个水平的抗性高度相关，表明生物体与器官之间的生物水平趋同。然而，库氏Th. couchii在群体之间的Navloci中没有功能变异或候选基因表达的差异。在其他类群中发现的基因型和表型之间的关系不能解释库奇氏钍中TTX抗性的局部变异。因此，历史的偶然性可能导致不同种类的Thamnophis下降替代路线，以适应当地。
The repeated evolution of tetrodotoxin (TTX) resistance provides a model for testing hypotheses about the mechanisms of convergent evolution. This poison is broadly employed as a potent antipredator defence, blocking voltage‐gated sodium channels (Nav) in muscles and nerves, paralysing and sometimes killing predators. Resistance in taxa bearing this neurotoxin and a few predators appears to come from convergent replacements in specific Navresidues that interact with TTX. This stereotyped genetic response suggests molecular and phenotypic evolution may be constrained and predictable. Here, we investigate the extent of mechanistic convergence in garter snakes (Thamnophis) that prey on TTX‐bearing newts (Taricha) by examining the physiological and genetic basis of TTX resistance in the Sierra garter snake (Th. couchii). We characterize variation in this predatory adaptation across populations at several biological scales: whole‐animal TTX resistance; skeletal muscle resistance; functional genetic variation in three Navencoding loci; and levels of gene expression for one of these loci. We foundTh. couchiipossess extensive geographical variation in resistance at the whole‐animal and skeletal muscle levels. As in otherThamnophis, resistance at both levels is highly correlated, suggesting convergence across the biological levels linking organism to organ. However,Th. couchiishows no functional variation in Navloci among populations or difference in candidate gene expression. Local variation in TTX resistance inTh. couchiicannot be explained by the same relationship between genotype and phenotype seen in other taxa. Thus, historical contingencies may lead different species ofThamnophisdown alternative routes to local adaptation.