Arcella Tracy, Hood Glen R, Powell Thomas H Q, Sim Sheina B, Yee Wee L, Schwarz Dietmar, Egan Scott P, Goughnour Robert B, Smith James J, Feder Jeffrey L
Department of Biological Sciences, University of Notre Dame Notre Dame, IN, USA.
USDA-ARS, Yakima Agricultural Research Laboratory Wapato, WA, USA.
Evol Appl. 2015 Sep;8(8):834-46. doi: 10.1111/eva.12298. Epub 2015 Aug 13.
Hybridization may be an important process interjecting variation into insect populations enabling host plant shifts and the origin of new economic pests. Here, we examine whether hybridization between the native snowberry-infesting fruit fly Rhagoletis zephyria (Snow) and the introduced quarantine pest R. pomonella (Walsh) is occurring and may aid the spread of the latter into more arid commercial apple-growing regions of central Washington state, USA. Results for 19 microsatellites implied hybridization occurring at a rate of 1.44% per generation between the species. However, there was no evidence for increased hybridization in central Washington. Allele frequencies for seven microsatellites in R. pomonella were more 'R. zephyria-like' in central Washington, suggesting that genes conferring resistance to desiccation may be adaptively introgressing from R. zephyria. However, in only one case was the putatively introgressing allele from R. zephyria not found in R. pomonella in the eastern USA. Thus, many of the alleles changing in frequency may have been prestanding in the introduced R. pomonella population. The dynamics of hybridization are therefore complex and nuanced for R. pomonella, with various causes and factors, including introgression for a portion, but not all of the genome, potentially contributing to the pest insect's spread.
杂交可能是一个重要过程，它将变异引入昆虫种群，促成寄主植物转移以及新的经济害虫的产生。在此，我们研究了以雪果为食的本土果蝇泽氏绕实蝇（Rhagoletis zephyria (Snow)）与引入的检疫性害虫苹果实蝇（R. pomonella (Walsh)）之间是否正在发生杂交，以及这种杂交是否会帮助后者扩散到美国华盛顿州中部更干旱的商业苹果种植区。对19个微卫星的研究结果表明，这两个物种之间的杂交发生率为每代1.44%。然而，没有证据表明华盛顿中部的杂交现象有所增加。在华盛顿中部，苹果实蝇中七个微卫星的等位基因频率更“像泽氏绕实蝇”，这表明赋予抗旱能力的基因可能正从泽氏绕实蝇适应性渐渗。然而，仅在一个案例中，在美国东部的苹果实蝇中未发现推测来自泽氏绕实蝇的渐渗等位基因。因此，许多频率发生变化的等位基因可能在引入的苹果实蝇种群中早已存在。所以，对于苹果实蝇来说，杂交动态复杂且微妙，有多种原因和因素，包括部分而非全部基因组的渐渗，都可能促使这种害虫扩散。
