Divergent diapause life history timing drives both allochronic speciation and reticulate hybridization in an adaptive radiation of Rhagoletis flies
Divergent diapause life history timing drives both allochronic speciation and reticulate hybridization in an adaptive radiation of Rhagoletis flies
复制标题
DOI：
10.1111/mec.15908
复制
发表时间：
2021-04-22
影响因子：
4.9
通讯作者：
Feder, Jeffrey L.
中科院分区：
文献类型：
--
作者：
Inskeep, Katherine A.;Doellman, Meredith M.;Feder, Jeffrey L.
对新生态机会的分化适应可能是启动物种形成的重要因素。然而，由于生态位在适应性辐射中被填满，性状分化驱动姐妹类群之间的生殖隔离也可能导致性状趋同，从而增加了辐射中网状基因流动的可能性。在这里，我们在最近的Rhagoletis果蝇的适应性辐射中证明了这种情况，它们专门针对不同的寄主植物。在整个辐射过程中，向新宿主的转移与滞育生活史时间的变化有关，这是一种“神奇性状”，产生异速生殖隔离，促进物种与基因流动。来自实验室饲养实验、测量成虫羽化时间和全基因组dna测序调查的证据支持夏季结果的牛痘菌侵染的门氏Rhagoletis与秋季结果的sparkleberries侵染的假想和未描述的姐妹分类群之间的异速物种形成。结果表明，花莓蝇和门达蝇是遗传上离散的姐妹类群，没有可检测到的基因流动，并通过与宿主可用性相对应的2个月的平均羽化时间差异进行异源分离。在美国南部的同域地点，花莓较晚的结果物候与开花的山茱萸重叠，山茱萸是另一个更远的亲缘关系和未描述的Rhagoletis分类单元的宿主。实验室涌现数据证实了广泛重叠的生活史时间和基因组证据支持在花楸和开花茱萸蝇之间持续的基因流动。因此，不同的物候适应可以驱动生殖隔离的启动，同时也加强了更广泛的适应辐射的遗传交换，可能成为新基因型变异的来源，并加强进一步的多样化。
Divergent adaptation to new ecological opportunities can be an important factor initiating speciation. However, as niches are filled during adaptive radiations, trait divergence driving reproductive isolation between sister taxa may also result in trait convergence with more distantly related taxa, increasing the potential for reticulated gene flow across the radiation. Here, we demonstrate such a scenario in a recent adaptive radiation of Rhagoletis fruit flies, specialized on different host plants. Throughout this radiation, shifts to novel hosts are associated with changes in diapause life history timing, which act as "magic traits" generating allochronic reproductive isolation and facilitating speciation-with-gene-flow. Evidence from laboratory rearing experiments measuring adult emergence timing and genome-wide DNA-sequencing surveys supported allochronic speciation between summer-fruiting Vaccinium spp.-infesting Rhagoletis mendax and its hypothesized and undescribed sister taxon infesting autumn-fruiting sparkleberries. The sparkleberry fly and R. mendax were shown to be genetically discrete sister taxa, exhibiting no detectable gene flow and allochronically isolated by a 2-month average difference in emergence time corresponding to host availability. At sympatric sites across the southern USA, the later fruiting phenology of sparkleberries overlaps with that of flowering dogwood, the host of another more distantly related and undescribed Rhagoletis taxon. Laboratory emergence data confirmed broadly overlapping life history timing and genomic evidence supported on-going gene flow between sparkleberry and flowering dogwood flies. Thus, divergent phenological adaptation can drive the initiation of reproductive isolation, while also enhancing genetic exchange across broader adaptive radiations, potentially serving as a source of novel genotypic variation and accentuating further diversification.