Local prey community composition and genetic distance predict venom divergence among populations of the northern Pacific rattlesnake (Crotalus oreganus)
Local prey community composition and genetic distance predict venom divergence among populations of the northern Pacific rattlesnake (Crotalus oreganus)
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DOI：
10.1111/jeb.13347
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发表时间：
2018-10-01
影响因子：
2.1
通讯作者：
Gibbs, H. Lisle
中科院分区：
文献类型：
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作者：
Holding, Matthew L.;Margres, Mark J.;Gibbs, H. Lisle
识别种群间功能性状差异的环境相关性可以深入了解产生局部适应的进化机制。在这里，我们评估的模式，在北方太平洋响尾蛇（响尾蛇oreganus）从13个地点在整个加州表达毒液蛋白的人口分化。我们评估了主要生物（猎物物种群落组成），非生物（温度，降水量和海拔）和遗传因素（基于RAD-seq基因座的遗传距离）的相对重要性，作为毒液表型的群体分歧的相关因素。我们发现，超过一半的毒液组成的变化与遗传和环境变量的种群分化，这种变化发生沿着轴定义先前观察到的功能之间的权衡毒液蛋白质，具有神经毒性，肌肉毒性和出血性的影响。令人惊讶的是，种群间的遗传分化是毒液分歧的最佳预测因子，占总体变异的46%，而猎物群落组成和非生物因素的差异解释了较小的变异量（分别为23%和19%）。遗传分化和毒液成分之间的关联可能是由于隔离的距离效应，或者更可能的是，隔离的环境效应，对最近的移民选择是强大的，中性的遗传分化和毒液分化之间的相关性。我们的研究结果表明，即使是粗略的估计猎物社区组成可以是有用的理解选择压力作用于毒液蛋白质表达模式。此外，我们的研究结果表明，在解释种群差异的毒液时，需要考虑的因素比适应猎物的空间变化。
Identifying the environmental correlates of divergence in functional traits between populations can provide insights into the evolutionary mechanisms that generate local adaptation. Here, we assess patterns of population differentiation in expressed venom proteins in Northern Pacific rattlesnakes (Crotalus oreganus) from 13 locations across California. We evaluate the relative importance of major biotic (prey species community composition), abiotic (temperature, precipitation and elevation) and genetic factors (genetic distance based on RAD-seq loci) as correlates of population divergence in venom phenotypes. We found that over half of the variation in venom composition is associated with among-population differentiation for genetic and environmental variables and that this variation occurred along axes defining previously observed functional trade-offs between venom proteins that have neurotoxic, myotoxic and hemorrhagic effects. Surprisingly, genetic differentiation among populations was the best predictor of venom divergence, accounting for 46% of overall variation, whereas differences in prey community composition and abiotic factors explained smaller amounts of variation (23% and 19%, respectively). The association between genetic differentiation and venom composition could be due to an isolation-by-distance effect or, more likely, an isolation-by-environment effect where selection against recent migrants is strong, producing a correlation between neutral genetic differentiation and venom differentiation. Our findings suggest that even coarse estimates of prey community composition can be useful in understanding the selection pressures acting on patterns of venom protein expression. Additionally, our results suggest that factors other than adaptation to spatial variation in prey need to be considered when explaining population divergence in venom.