Department of Zoology, Faculty of Science, Charles University, Viničná 7, 128 44, Prague, Czech Republic.
Institute of Vertebrate Biology, Czech Academy of Sciences, Květná 8, Brno, 603 65, Czech Republic.
BMC Ecol Evol. 2021 Mar 10;21(1):41. doi: 10.1186/s12862-021-01773-1.
It has been proposed that divergence in the gut microbiota composition between incipient species could contribute to their reproductive isolation. Nevertheless, empirical evidence for the role of gut microbiota in speciation is scarce. Moreover, it is still largely unknown to what extent closely related species in the early stages of speciation differ in their gut microbiota composition, especially in non-mammalian taxa, and which factors drive the divergence. Here we analysed the gut microbiota in two closely related passerine species, the common nightingale (Luscinia megarhynchos) and the thrush nightingale (Luscinia luscinia). The ranges of these two species overlap in a secondary contact zone, where both species occasionally hybridize and where interspecific competition has resulted in habitat use differentiation.
We analysed the gut microbiota from the proximal, middle and distal part of the small intestine in both sympatric and allopatric populations of the two nightingale species using sequencing of bacterial 16S rRNA. We found small but significant differences in the microbiota composition among the three gut sections. However, the gut microbiota composition in the two nightingale species did not differ significantly between either sympatric or allopatric populations. Most of the observed variation in the gut microbiota composition was explained by inter-individual differences.
To our knowledge, this is the first attempt to assess the potential role of the gut microbiota in bird speciation. Our results suggest that neither habitat use, nor geographical distance, nor species identity have strong influence on the nightingale gut microbiota composition. This suggests that changes in the gut microbiota composition are unlikely to contribute to reproductive isolation in these passerine birds.
有人提出，肠道微生物群落组成在初期物种之间的差异可能有助于它们的生殖隔离。然而，肠道微生物群在物种形成中的作用的经验证据很少。此外，在物种形成的早期阶段，密切相关的物种在肠道微生物群落组成上有多大程度的差异，特别是在非哺乳动物类群中，以及哪些因素驱动了这种差异，仍然在很大程度上是未知的。在这里，我们分析了两种密切相关的雀形目鸟类，普通夜莺（Luscinia megarhynchos）和画眉夜莺（Luscinia luscinia）的肠道微生物群。这两个物种的分布范围在一个次要接触区重叠，在这个区域，这两个物种偶尔会杂交，并且种间竞争导致了栖息地利用的分化。
我们使用细菌 16S rRNA 测序分析了这两个夜莺物种的近交和远交种群的小肠近端、中端和远端的肠道微生物群。我们发现三个肠道部位的微生物群落组成有微小但显著的差异。然而，两种夜莺物种的肠道微生物群落组成在同域或异域种群之间没有显著差异。观察到的肠道微生物群落组成的大部分变异可以用个体间差异来解释。
据我们所知，这是首次尝试评估肠道微生物群在鸟类物种形成中的潜在作用。我们的结果表明，无论是栖息地利用、地理距离还是物种身份，对夜莺肠道微生物群落组成都没有强烈的影响。这表明，肠道微生物群落组成的变化不太可能导致这些雀形目鸟类的生殖隔离。
