Gut microbiomes and reproductive isolation in Drosophila.

<b>In Drosophilids, the microbiome is reported as flexible and largely environmentally-determined. Therefore, RI would be transient and break down under dietary variation. In the absence of co-association between host and microbiome, there are also no advantages for the gut bacteria or host in effecting RI. To explore these puzzling effects and their mechanisms further, we repeated the tests for RI associated with diet-specific gut microbiomes in <i>D. melanogaster </i>found in Sharon et al 2011. Despite observing differences in the gut microbiomes in flies maintained on different diets, we found no evidence for diet-associated RI or for any role of gut bacteria, or for <i>L. plantarum </i>specifically<i>.</i> The results suggest that there is no general role for gut bacteria in driving the evolution of RI in this species and hence resolve this evolutionary riddle.</b>

在果蝇科（Drosophilids）昆虫中，肠道菌群被证实具有较强的可塑性，且其群落组成主要由环境决定。据此推测，生殖隔离（Reproductive Isolation, RI）应呈现暂时性特征，且在饮食结构改变的情况下会发生瓦解。若宿主与肠道菌群之间不存在稳定的共关联关系，则肠道细菌与宿主均无法从介导生殖隔离的过程中获取任何收益。为进一步探究这一令人困惑的科学现象及其背后的作用机制，我们针对2011年Sharon等人研究中涉及的黑腹果蝇（Drosophila melanogaster），重复开展了与饮食特异性肠道菌群相关的生殖隔离实验。尽管我们观察到不同饮食饲养的果蝇其肠道菌群组成存在显著差异，但未发现任何证据表明存在与饮食相关的生殖隔离，也未发现肠道菌群（尤其是植物乳杆菌（Lactobacillus plantarum））在其中发挥任何作用。本研究结果表明，肠道菌群在该物种生殖隔离的演化进程中并未发挥普遍作用，从而解开了这一进化谜题。