Biological and Environmental Sciences, University of Stirling, Stirling, UK.
Mol Ecol. 2018 Mar;27(5):1095-1097. doi: 10.1111/mec.14444.
Determining the long-term consequences of hybridization remains a central quest for evolutionary biologists. A particular challenge is to establish whether and to what extent widespread hybridization results in gene flow (introgression) between parental taxa. In this issue of Molecular Ecology, Jordan et al. () search for evidence of gene flow between two closely related species of Geum (Rosaceae), which hybridize readily in contemporary populations and where hybrid swarms have been recorded for at least 200 years (Ruhsam, Hollingsworth, & Ennos, ). The authors find mixed evidence of ancient introgression when analysing allopatric populations. Intriguingly, when analysing populations of a region where the two species occur either mixed in the same population or in close proximity, and where hybrids are presently common, Jordan and colleagues find that the majority of randomly sampled individuals analysed (92/96) show no evidence of introgression (defined as individuals with admixture coefficients of <1%). The few individuals identified as hybrids are shown to likely be F1 or early-generation backcrosses, indicating that even in sympatric regions, hybridization does not penetrate beyond a few generations. Based on their findings, Geum seems to be an example of little to no introgression despite contemporary hybridization.
确定杂交的长期后果仍然是进化生物学家的核心研究课题。一个特别的挑战是确定广泛的杂交是否以及在何种程度上导致亲代分类群之间发生基因流动（基因渗入）。在本期的《分子生态学》中，Jordan 等人（）搜索了两种密切相关的 Geum 物种（蔷薇科）之间基因流动的证据，这两种物种在现代种群中很容易杂交，并且已经记录到杂交群至少有 200 年的历史（Ruhsam、Hollingsworth 和 Ennos，）。作者在分析异域种群时发现了古代基因渗入的混合证据。有趣的是，当分析两个物种在同一种群或近距离共存的地区的种群时，以及当杂种目前很常见时，Jordan 和同事发现，分析的大多数随机抽样个体（92/96）没有基因渗入的证据（定义为混合系数<1%的个体）。少数被鉴定为杂种的个体很可能是 F1 或早期世代回交，表明即使在同域地区，杂交也不会超过几代。根据他们的发现，Geum 似乎是一个尽管存在当代杂交，但基因渗入很少甚至没有的例子。
