Department of Entomology and Acarology, University of São Paulo, Luiz de Queiroz College of Agriculture, Piracicaba, São Paulo, 13418900, Brazil.
Department of Entomology & The Center for Applied Plant Sciences, Ohio Agricultural Research and Development Center, Thorne Hall, The Ohio State University, 1680 Madison Ave, Wooster, OH, 44691, USA.
BMC Evol Biol. 2020 May 25;20(1):61. doi: 10.1186/s12862-020-01621-8.
Invasion of organisms into new ecosystems is increasingly common, due to the global trade in commodities. One of the most complex post-invasion scenarios occurs when an invasive species is related to a native pest, and even more so when they can hybridize and produce fertile progeny. The global pest Helicoverpa armigera was first detected in Brazil in 2013 and generated a wave of speculations about the possibility of hybridization with the native sister taxon Helicoverpa zea. In the present study, we used genome-wide single nucleotide polymorphisms from field-collected individuals to estimate hybridization between H. armigera and H. zea in different Brazilian agricultural landscapes.
The frequency of hybridization varied from 15 to 30% depending on the statistical analyses. These methods showed more congruence in estimating that hybrids contained approximately 10% mixed ancestry (i.e. introgression) from either species. Hybridization also varied considerably depending on the geographic locations where the sample was collected, forming a 'mosaic' hybrid zone where introgression may be facilitated by environmental and landscape variables. Both landscape composition and bioclimatic variables indicated that maize and soybean cropland are the main factors responsible for high levels of introgression in agricultural landscapes. The impact of multiple H. armigera incursions is reflected in the structured and inbred pattern of genetic diversity.
Our data showed that the landscape composition and bioclimatic variables influence the introgression rate between H. armigera and H. zea in agricultural areas. Continuous monitoring of the hybridization process in the field is necessary, since agricultural expansion, climatic fluctuations, changing composition of crop species and varieties, and dynamic planting seasons are some factors in South America that could cause a sudden alteration in the introgression rate between Helicoverpa species. Introgression between invasive and native pests can dramatically impact the evolution of host ranges and resistance management.
由于商品的全球贸易，生物入侵到新生态系统的情况越来越常见。入侵物种与本地害虫相关的情况下，入侵后最复杂的情况之一就是发生杂交，并且当它们能够杂交并产生可育后代时更是如此。全球害虫棉铃虫于 2013 年首次在巴西被发现，这引发了人们对其与本地姊妹种 H.zea 发生杂交可能性的猜测。在本研究中，我们使用来自田间采集个体的全基因组单核苷酸多态性来估计巴西不同农业景观中 H.armigera 和 H.zea 之间的杂交。
杂交频率因统计分析而异，从 15%到 30%不等。这些方法在估计杂种中大约有 10%的混合血统（即基因渐渗）来自这两个物种时更为一致。杂交也因采样地点的地理位置而异，形成了一个“马赛克”杂种区，环境和景观变量可能促进基因渐渗。景观组成和生物气候变量都表明，玉米和大豆种植区是农业景观中高水平基因渐渗的主要因素。多次棉铃虫入侵的影响反映在遗传多样性的结构和近交模式上。
我们的数据表明，景观组成和生物气候变量影响农业区 H.armigera 和 H.zea 之间的基因渐渗率。有必要对田间杂交过程进行持续监测，因为农业扩张、气候波动、作物种类和品种组成的变化以及动态种植季节等因素在南美洲可能导致 Helicoverpa 物种之间的基因渐渗率突然改变。入侵种与本地害虫之间的基因渐渗会对宿主范围的进化和抗药性管理产生巨大影响。
