Poveda-Martínez Daniel, Varone Laura, Fuentes Corona Malena, Hight Stephen, Logarzo Guillermo, Hasson Esteban
Fundación para el Estudio de Especies Invasivas (FuEDEI), Hurlingham, Buenos Aires, Argentina.
Instituto de Ecología Genética y Evolución de Buenos Aires (IEGEBA), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.
Mol Ecol. 2022 Jan;31(1):356-371. doi: 10.1111/mec.16232. Epub 2021 Oct 27.
Surveys of patterns of genetic variation in natural sympatric and allopatric populations of recently diverged species are necessary to understand the processes driving intra- and interspecific diversification. The South American moths Cactoblastis cactorum, Cactoblastis doddi and Cactoblastis bucyrus are specialized in the use of cacti as host plants. These species have partially different geographic ranges and differ in patterns of host plant use. However, there are areas that overlap, particularly, in northwestern Argentina, where they are sympatric. Using a combination of genome-wide SNPs and mitochondrial data we assessed intra and interspecific genetic variation and investigated the relative roles of geography and host plants on genetic divergence. We also searched for genetic footprints of hybridization between species. We identified three well delimited species and detected signs of hybridization in the area of sympatry. Our results supported a hypothetical scenario of allopatric speciation in the generalist C. cactorum and genetic interchange during secondary geographic contact with the pair of specialists C. bucyrus and C. doddi that probably speciated sympatrically. In both cases, adaptation to new host plants probably played an important role in speciation. The results also suggested the interplay of geography and host plant use as drivers of divergence and limiting gene flow at intra and interspecific levels.
调查最近分化物种的自然同域和异域种群中的遗传变异模式，对于理解驱动种内和种间多样化的过程至关重要。南美蛾类仙人掌螟、多氏仙人掌螟和布氏仙人掌螟专门以仙人掌为寄主植物。这些物种的地理分布范围部分不同，寄主植物利用模式也有所差异。然而，存在一些重叠区域，特别是在阿根廷西北部，它们在那里同域分布。我们结合全基因组单核苷酸多态性（SNP）和线粒体数据，评估了种内和种间的遗传变异，并研究了地理因素和寄主植物在遗传分化中的相对作用。我们还寻找了物种间杂交的遗传印记。我们识别出三个界限分明的物种，并在同域分布区域检测到杂交迹象。我们的结果支持了一种假设情景：广食性的仙人掌螟经历了异域物种形成，而在与可能同域物种形成的专食性布氏仙人掌螟和多氏仙人掌螟的二次地理接触过程中发生了基因交流。在这两种情况下，对新寄主植物的适应可能在物种形成中发挥了重要作用。结果还表明，地理因素和寄主植物利用在种内和种间水平上作为分化驱动因素和限制基因流动的相互作用。
