Data from: Genetic differentiation associated with host plants and geography among six widespread species of South American Blepharoneura fruit flies (Tephritidae)

Tropical herbivorous insects are astonishingly diverse and many are highly host-specific. Much evidence suggests that herbivorous insect diversity is a function of host-plant diversity; yet, the diversity of some lineages exceeds the diversity of plants. Although most species of herbivorous fruit flies in the Neotropical genus Blepharoneura are strongly host-specific (they deposit their eggs in a single host plant species and flower sex), some species are collected from multiple hosts or flowers and these may represent examples of lineages that are diversifying via changes in host use. Here, we investigate patterns of diversification within six geographically widespread Blepharoneura species that have been collected and reared from at least two host-plant species or host-plant parts. We use microsatellites to: 1) test for evidence of local genetic differentiation associated with different sympatric hosts (different plant species or flower sexes); and 2) examine geographic patterns of genetic differentiation across multiple South American collection sites. In four of the six fly species, we find evidence of local genetic differences between flies collected from different hosts. All six species show evidence of geographic structure, with consistent differences between flies collected in the Guianan Shield and flies collected in Amazonia. Continent-wide analyses reveal - in all but one instance - that genetically differentiated flies collected in sympatry from different host species or different sex flowers are not one another's closest relatives, indicating that genetic differences often arise in allopatry before, or at least coincident with, the evolution of novel host use.

热带植食性昆虫的物种多样性极为惊人，其中多数类群具有极强的宿主专一性（host-specific）。大量研究证据表明，植食性昆虫的多样性与宿主植物的多样性呈显著正相关；然而部分昆虫支系的物种多样性却远超其宿主植物类群。尽管新热带区Blepharoneura属的多数植食性实蝇具有严格的宿主专一性——仅将卵产于单一宿主植物物种及其特定性别的花部结构中，但部分物种可从多种宿主或不同花部中采集得到，这类类群或代表了通过宿主利用策略改变而实现物种分化的典型实例。本研究针对6种地理分布广泛的Blepharoneura实蝇展开分析，这些类群均采集自至少两种宿主植物物种或不同植物组织，并经人工饲养获得。本研究采用微卫星（microsatellite）标记开展两项核心分析：其一，检验不同同域（sympatric）宿主（不同植物物种或花部性别）对应的实蝇是否存在局部遗传分化；其二，探究多个南美采样点间实蝇的遗传分化地理格局。研究结果显示，在6个实蝇物种中的4个物种内，不同宿主来源的实蝇之间存在显著的局部遗传差异。所有6个物种均表现出清晰的地理遗传结构：圭亚那地盾（Guianan Shield）采样点的实蝇与亚马孙流域（Amazonia）采样点的实蝇之间存在稳定的遗传分化。跨大陆尺度的分析结果进一步表明：除1个例外情况外，同域分布且来自不同宿主物种或不同性别花部的遗传分化实蝇，彼此间并非最近缘类群；这意味着遗传分化通常是在新型宿主利用策略演化之前，或至少与其同步发生的异域分化（allopatry）过程中形成的。