Data from: Crop domestication facilitated rapid geographic expansion of a specialist pollinator, the squash bee Peponapis pruinosa

Squash was first domesticated in Mexico and is now found throughout North America along with Peponapis pruinosa, a pollen specialist bee species of the squash genus Cucurbita. The origin and spread of squash cultivation is well-studied archeologically and phylogenetically; however, no study has documented how cultivation of this or any other crop has influenced species in mutualistic interactions. We used molecular markers to reconstruct the demographic range expansion and colonization routes of P. pruinosa from its native range into temperate North America. Populations east of the Rocky Mountains expanded from the wild host plant’s range in Mexico and were established by a series of founder events. Eastern North America was most likely colonized from squash bee populations in present-day continental Midwest US and not from routes that followed the Gulf and Atlantic coasts from Mexico. Populations of P. pruinosa west of the Rockies spread north from the warm deserts much more recently, showing two genetically differentiated populations with no admixture: one in California and the other one in eastern Great Basin. These bees have repeatedly endured severe bottlenecks as they colonized North America, following human spread of their Cucurbita pollen hosts during the Holocene.南瓜（Squash）最早于墨西哥被驯化，如今已与南瓜蜂（Peponapis pruinosa）——一种南瓜属（Cucurbita）花粉专性蜂类——一同分布于整个北美大陆。南瓜栽培的起源与传播路径已在考古学与系统发育学领域得到充分研究，但目前尚无任何研究阐明此类作物（或其他任何作物）的种植如何影响与其存在互利共生互作关系的物种种群。本研究利用分子标记重构了南瓜蜂从原生分布区向北美温带地区扩张的种群范围动态与定殖路线。落基山脉以东的南瓜蜂种群源自墨西哥境内的野生寄主植物分布区，并通过一系列奠基者事件建立种群。北美东部区域的种群最有可能源自现今美国大陆中西部地区的南瓜蜂种群，而非沿墨西哥湾与大西洋沿岸从墨西哥出发的传播路径。落基山脉以西的南瓜蜂种群则是在更近的时期从暖荒漠区域向北扩散形成，目前存在两个遗传分化显著且无基因交流的种群：一个分布于加利福尼亚州，另一个分布于大盆地东部。在全新世时期，这些蜂类跟随人类对其花粉寄主南瓜属植物的传播路径定殖北美大陆，期间多次经历了严重的种群瓶颈事件。