Data from: Rapid and Repeatable Host Plant Shifts Drive Reproductive Isolation Following a Recent Human-Mediated Introduction of the Apple Maggot Fly, Rhagoletis pomonella

Ecological speciation via host-shifting is often invoked as a mechanism for insect diversification, but the relative importance of this process is poorly understood. The shift of Rhagoletis pomonella in the 1850s from the native downy hawthorn, Crataegus mollis, to introduced apple, Malus pumila, is a classic example of sympatric host race formation, a hypothesized early stage of ecological speciation. The accidental human-mediated introduction of R. pomonella into the Pacific Northwest (PNW) in the late-1970's allows us to investigate how novel ecological opportunities may trigger divergent adaptation and host race formation on a rapid timescale. Since the introduction, the fly has spread in the PNW, where in addition to apple, it now infests native black hawthorn, C. douglasii, and introduced ornamental hawthorn, C. monogyna. We use this "natural experiment" to test for genetic differentiation among apple, black and ornamental hawthorn flies co-occurring at three sympatric sites. We report evidence that populations of all three host-associations are genetically differentiated at the local level, indicating that partial reproductive isolation has evolved in this novel habitat. Our results suggest that conditions suitable for initiating host-associated divergence may be common in nature, allowing for the rapid evolution of new host races when ecological opportunity arises.

宿主转换介导的生态物种形成常被视为昆虫物种多样化的潜在机制，但该过程的相对重要性迄今仍未得到充分解析。19世纪50年代，苹果实蝇（Rhagoletis pomonella）从原生宿主绒毛山楂（Crataegus mollis）转换至引种苹果（Malus pumila）的事件，是同域宿主宗形成（sympatric host race formation）的经典案例——而同域宿主宗形成被假说是生态物种形成的早期阶段。20世纪70年代末，苹果实蝇经人类活动偶然传入太平洋西北地区（Pacific Northwest, PNW），为我们探究新型生态机遇如何在快速时间尺度下触发趋异适应与宿主宗形成提供了研究契机。自传入以来，该实蝇已在太平洋西北地区扩散；如今除苹果外，它还寄生了原生黑山楂（C. douglasii）与引种观赏山楂（C. monogyna）。我们依托这一“自然实验”，对3个同域采样点中共存的苹果、黑山楂与观赏山楂寄主实蝇种群开展遗传分化检测。本研究证实，三类宿主关联的实蝇种群在局域尺度下均存在遗传分化，表明该新生境中已演化出部分生殖隔离。本研究结果表明，能够引发宿主相关分化的适宜条件在自然界中或较为普遍；当生态机遇出现时，新宿主宗可快速演化形成。

搜集汇总

背景与挑战

背景概述

该数据集基于苹果实蝇（Rhagoletis pomonella）的宿主植物转移研究，探讨生态物种形成过程。它包含苹果实蝇从原生山楂转向苹果，以及引入太平洋西北地区后在多种山楂宿主上形成遗传分化的数据，揭示了人类介导引入如何促进宿主种族快速演化和生殖隔离。