Data from: Recent population decline and selection shape diversity of taxol-related genes

Taxanes are defensive metabolites produced by Taxus species (yews) and
used in anticancer therapies. Despite their medical interest, patterns of
natural diversity in taxane related genes are unknown. We examined
variation at five main taxol-related genes of T. baccata in the Iberian
Peninsula, a region where unique yew genetic resources are endangered. We
looked at several gene features and applied complementary neutrality
tests, including diversity/divergence tests, tests solely based on
site-frequency spectrum and Zeng’s compound tests. To account for specific
demography, microsatellite data were used to infer historical changes in
population size based on an Approximate Bayesian Computation (ABC)
approach. Polymorphism-divergence tests pointed to positive selection for
genes TBT and TAT, and balancing selection for DBAT. In addition,
neutrality tests based on site-frequency spectrum found that while a
recent reduction in population size may explain most of statistics’
values, selection may still be in action in genes TBT and DBAT, at least
in some populations. Molecular signatures on taxol genes suggest the
action of frequent selective waves with different direction or intensity,
possibly related to varying adaptive pressures produced by the host-enemy
co-evolution on defense-related genes. Such natural selection processes
may have produced taxane variants still undiscovered.

紫杉烷（Taxanes）是紫杉属（红豆杉）植物产生的防御性代谢物，广泛应用于抗癌治疗。尽管其具有重要医学价值，但紫杉烷相关基因的自然多样性模式尚不明确。本研究分析了伊比利亚半岛欧洲红豆杉（T. baccata）中五个关键紫杉醇相关基因的变异特征——该地区独特的红豆杉遗传资源正面临濒危风险。研究考察了多个基因特征，并应用了互补的中性检验方法，包括多样性/分化检验、仅基于位点频率谱的检验以及曾氏复合检验（Zeng’s compound tests）。为了纳入特定的种群 demographic 特征，研究利用微卫星数据，通过近似贝叶斯计算（Approximate Bayesian Computation, ABC）方法推断种群规模的历史变化。多态性-分化检验结果显示，TBT和TAT基因存在正选择信号，而DBAT基因表现出平衡选择特征。此外，基于位点频率谱的中性检验表明：尽管近期种群规模缩减可能解释大部分统计值，但选择作用仍可能在TBT和DBAT基因中持续存在（至少在部分种群中如此）。紫杉醇基因的分子特征暗示，频繁且方向或强度各异的选择性波动，可能与宿主-天敌协同进化对防御相关基因施加的适应性压力变化有关。这种自然选择过程或已产生尚未被发现的紫杉烷变体。