Hopper Julie V, McCue Kent F, Pratt Paul D, Duchesne Pierre, Grosholz Edwin D, Hufbauer Ruth A
Department of Biological Sciences University of Southern California Los Angeles California.
Crop Improvement and Genetics Research Unit USDA/ARS Albany California.
Evol Appl. 2019 Jan 4;12(4):773-790. doi: 10.1111/eva.12755. eCollection 2019 Apr.
The intentional introduction of exotic species through classical biological control programs provides unique opportunities to examine the consequences of population movement and ecological processes for the genetic diversity and population structure of introduced species. The weevils and (Coleoptera: Curculionidae) have been introduced globally to control the invasive floating aquatic weed, , with variable outcomes. Here, we use the importation history and data from polymorphic microsatellite markers to examine the effects of introduction processes on population genetic diversity and structure. We report the first confirmation of hybridization between these species, which could have important consequences for the biological control program. For both species, there were more rare alleles in weevils from the native range than in weevils from the introduced range. also had higher allelic richness in the native range than in the introduced range. Neither the number of individuals initially introduced nor the number of introduction steps appeared to consistently affect genetic diversity. We found evidence of genetic drift, inbreeding, and admixture in several populations as well as significant population structure. Analyses estimated two populations and 11 sub-clusters for and four populations and 23 sub-clusters for , indicating divergence of populations during and after introduction. Genetic differentiation and allocation of introduced populations to source populations generally supported the documented importation history and clarified pathways in cases where multiple introductions occurred. In populations with multiple introductions, genetic admixture may have buffered against the negative effects of serial bottlenecks on genetic diversity. The genetic data combined with the introduction history from this biological control study system provide insight on the accuracy of predicting introduction pathways from genetic data and the consequences of these pathways for the genetic variation and structure of introduced species.
通过经典生物防治计划有意引入外来物种，为研究种群迁移和生态过程对引入物种的遗传多样性和种群结构的影响提供了独特的机会。象鼻虫（鞘翅目：象甲科）已在全球范围内被引入，以控制入侵性漂浮水生杂草凤眼蓝，但其结果各不相同。在这里，我们利用引入历史和多态微卫星标记的数据，研究引入过程对种群遗传多样性和结构的影响。我们首次证实了这些物种之间的杂交，这可能对生物防治计划产生重要影响。对于这两个物种，来自原生范围的象鼻虫中稀有等位基因比来自引入范围的象鼻虫更多。凤眼蓝在原生范围内的等位基因丰富度也高于引入范围内。最初引入的个体数量和引入步骤数量似乎都没有始终如一地影响遗传多样性。我们在几个种群中发现了遗传漂变、近亲繁殖和混合的证据，以及显著的种群结构。分析估计，凤眼蓝有两个种群和11个亚群，象鼻虫有四个种群和23个亚群，这表明在引入期间和引入之后种群发生了分化。引入种群与源种群的遗传分化和分配总体上支持了记录的引入历史，并在多次引入的情况下澄清了引入途径。在多次引入的种群中，遗传混合可能缓冲了连续瓶颈对遗传多样性的负面影响。结合该生物防治研究系统的引入历史的遗传数据，为从遗传数据预测引入途径的准确性以及这些途径对引入物种的遗传变异和结构的影响提供了见解。
