Helms Jackson A, Godfrey Aaron
Department of Biology, University of Oklahoma, Norman, Oklahoma, United States of America.
ZIN Technologies, Inc., Middleburg Heights, Ohio, United States of America.
PLoS One. 2016 Apr 15;11(4):e0153955. doi: 10.1371/journal.pone.0153955. eCollection 2016.
In the Found or Fly (FoF) hypothesis ant queens experience reproduction-dispersal tradeoffs such that queens with heavier abdomens are better at founding colonies but are worse flyers. We tested predictions of FoF in two globally invasive fire ants, Solenopsis geminata (Fabricius, 1804) and S. invicta (Buren, 1972). Colonies of these species may produce two different monogyne queen types-claustral queens with heavy abdomens that found colonies independently, and parasitic queens with small abdomens that enter conspecific nests. Claustral and parasitic queens were similarly sized, but the abdomens of claustral queens weighed twice as much as those of their parasitic counterparts. Their heavier abdomens adversely impacted morphological predictors of flight ability, resulting in 32-38% lower flight muscle ratios, 55-63% higher wing loading, and 32-33% higher abdomen drag. In lab experiments maximum flight durations in claustral S. invicta queens decreased by about 18 minutes for every milligram of abdomen mass. Combining our results into a simple fitness tradeoff model, we calculated that an average parasitic S. invicta queen could produce only 1/3 as many worker offspring as a claustral queen, but could fly 4 times as long and have a 17- to 36-fold larger potential colonization area. Investigations of dispersal polymorphisms and their associated tradeoffs promises to shed light on range expansions in invasive species, the evolution of alternative reproductive strategies, and the selective forces driving the recurrent evolution of parasitism in ants.
在“定居或飞行（FoF）”假说中，蚁后会经历繁殖 - 扩散权衡，即腹部较重的蚁后在建立蚁群方面表现更好，但飞行能力较差。我们在两种全球入侵性火蚁，即热带火蚁（Solenopsis geminata，Fabricius，1804）和红火蚁（S. invicta，Buren，1972）中测试了FoF的预测。这些物种的蚁群可能产生两种不同的单蚁后类型——腹部较重的封闭型蚁后独立建立蚁群，以及腹部较小的寄生型蚁后进入同种蚁巢。封闭型蚁后和寄生型蚁后大小相似，但封闭型蚁后的腹部重量是寄生型蚁后的两倍。它们较重的腹部对飞行能力的形态学预测指标产生了不利影响，导致飞行肌肉比例降低32 - 38%，翼载荷增加55 - 63%，腹部阻力增加32 - 33%。在实验室实验中，红火蚁封闭型蚁后的最大飞行持续时间每增加一毫克腹部质量就会减少约18分钟。将我们的结果整合到一个简单的适合度权衡模型中，我们计算出，平均而言，红火蚁寄生型蚁后产生的工蚁后代数量仅为封闭型蚁后的1/3，但飞行时间可以延长4倍，潜在的定殖面积大17至36倍。对扩散多态性及其相关权衡的研究有望揭示入侵物种的范围扩张、替代繁殖策略的进化以及推动蚂蚁寄生现象反复进化的选择力量。
