Department of Integrative Biology, University of South Florida, Tampa, FL, USA.
School of Biological Sciences, Washington State University, Pullman, WA, USA.
Genome Biol Evol. 2024 Sep 3;16(9). doi: 10.1093/gbe/evae198.
Understanding the proximate and ultimate causes of phenotypic variation is fundamental in evolutionary research, as such variation provides the substrate for selection to act upon. Although trait variation can arise due to selection, the importance of neutral processes is sometimes understudied. We presented the first reference-quality genome of the Red Diamond Rattlesnake (Crotalus ruber) and used range-wide 'omic data to estimate the degree to which neutral and adaptive evolutionary processes shaped venom evolution. We characterized population structure and found substantial genetic differentiation across two populations, each with distinct demographic histories. We identified significant differentiation in venom expression across age classes with substantially reduced but discernible differentiation across populations. We then used conditional redundancy analysis to test whether venom expression variation was best predicted by neutral divergence patterns or geographically variable (a)biotic factors. Snake size was the most significant predictor of venom variation, with environment, prey availability, and neutral sequence variation also identified as significant factors, though to a lesser degree. By directly including neutrality in the model, our results confidently highlight the predominant, yet not singular, role of life history in shaping venom evolution.
了解表型变异的近因和远因是进化研究的基础，因为这种变异为选择提供了作用的基础。尽管特征变异可能是由于选择而产生的，但中性过程的重要性有时研究不足。我们提供了红钻响尾蛇（Crotalus ruber）的第一个参考质量基因组，并利用全基因组范围的“组学”数据来估计中性和适应性进化过程在多大程度上塑造了毒液进化。我们描述了种群结构，并发现两个种群之间存在显著的遗传分化，每个种群都有不同的人口历史。我们发现毒液表达在年龄组之间存在显著的分化，尽管在种群之间存在明显的差异，但分化程度大大降低。然后，我们使用条件冗余分析来检验毒液表达变异是否可以通过中性分歧模式或地理上可变的（非生物）因素来最好地预测。蛇的大小是毒液变异的最显著预测因子，环境、猎物的可利用性和中性序列变异也被确定为重要因素，尽管程度较小。通过直接将中性纳入模型，我们的结果有信心地突出了生活史在塑造毒液进化中的主要作用，但不是唯一作用。
