Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA.
Department of Conservation Medicine, International Crane Foundation, Baraboo, WI, USA.
Proc Biol Sci. 2020 Mar 25;287(1923):20192988. doi: 10.1098/rspb.2019.2988. Epub 2020 Mar 18.
In numerous animal clades, the evolutionary history of host species drives patterns of gut microbial community structure, resulting in more divergent microbiota with increasing phylogenetic distance between hosts. This phenomenon, termed phylosymbiosis, has been observed in diverse evolutionary lineages, but has been difficult to detect in birds. Previous tests of phylosymbiosis among birds have been conducted using wild individuals, and thus interspecific differences in diet and environment may have masked a phylogenetic signal. Therefore, we tested for phylosymbiosis among all 15 species of cranes (family Gruidae) housed in the same captive environment and maintained on identical diets. 16S rRNA sequencing revealed that crane species harbour distinct gut microbiota. Overall, we detected marginally significant patterns of phylosymbiosis, the strength of which was increased when including the estimates of absolute microbial abundance (rather than relative abundance) derived from microbial densities determined by flow cytometry. Using this approach, we detected the statistically significant signatures of phylosymbiosis only after removing male cranes from our analysis, suggesting that using mixed-sex animal cohorts may prevent the detection of phylosymbiosis. Though weak compared with mammals (and especially insects), these results provide evidence of phylosymbiosis in birds. We discuss the potential differences between birds and mammals, such as transmission routes and host filtering, that may underlie the differences in the strength of phylosymbiosis.
在许多动物进化枝中，宿主物种的进化历史驱动着肠道微生物群落结构的模式，导致宿主之间的系统发育距离越远，微生物群就越多样化。这种现象被称为系统共生，在不同的进化谱系中都有观察到，但在鸟类中很难检测到。之前对鸟类系统共生的测试是在野生个体中进行的，因此饮食和环境的种间差异可能掩盖了系统发育信号。因此，我们在同一圈养环境中饲养的 15 种鹤（鹤科）中测试了系统共生，并对它们进行了相同的饮食。16S rRNA 测序显示，鹤种拥有独特的肠道微生物群。总体而言，我们检测到了系统共生的边缘显著模式，当包括从通过流式细胞术确定的微生物密度得出的绝对微生物丰度（而不是相对丰度）的估计值时，这种模式的强度增加了。使用这种方法，我们仅在从分析中去除雄性鹤后才检测到系统共生的统计学显著特征，这表明使用混合性别动物队列可能会阻止系统共生的检测。尽管与哺乳动物（尤其是昆虫）相比较弱，但这些结果为鸟类中的系统共生提供了证据。我们讨论了鸟类和哺乳动物之间的潜在差异，例如传播途径和宿主过滤，这可能是系统共生强度差异的基础。
