Variation in the Prevalence and Transmission of Heritable Symbionts Across Host Populations in Heterogeneous Environments
Variation in the Prevalence and Transmission of Heritable Symbionts Across Host Populations in Heterogeneous Environments
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DOI：
10.1007/s00248-017-0964-4
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发表时间：
2017-03
影响因子：
3.6
通讯作者：
Michelle E. Sneck;Jennifer A. Rudgers;C. Young;T. Miller
中科院分区：
文献类型：
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作者：
Michelle E. Sneck;Jennifer A. Rudgers;C. Young;T. Miller
可遗传的微生物在自然界中含量丰富，对其宿主及其居住的社区具有影响力。然而，遗传性共生体的流行及其传播率的变异驱动因素尚未得到很好的解决，特别是在经历可变生物和非生物环境的宿主群体中。为了填补这些空白，我们调查了美国大平原南部的 25 个本土草类（披碱草和加拿大披碱草）种群。这两种草种都寄生有可遗传的内生真菌（Epichloё属），并且可以在其范围重叠的地方杂交。我们利用与生物活性生物碱生产相关的基因位点，从宿主的一个子集中表征了内生菌基因型。首先，我们发现平均垂直传播率和人群水平的患病率呈正相关，特别是对于大肠杆菌。维吉尼库斯。然而，内生菌的流行率和传播在不同人群中差异很大，并且与非生物变量没有很强的相关性，但有一个例外：内生菌流行率随着干旱胁迫的减少而减少。维吉尼库斯主机。其次，我们评估了生物因素的潜在影响，发现在考虑气候因素后，内生菌基因型解释了共生体遗传的显着变化。我们还对比了宿主物种在同源性和异源性中共存的种群。同情可能会增加种间杂交，但该变量与共生体流行或传播成功的模式无关。我们的结果揭示了共生体在宿主群体中的流行和传播存在很大的变异性，并确定了共生体基因型，并在较小程度上确定了非生物环境是这种变异的来源。
Heritable microbes are abundant in nature and influential to their hosts and the communities in which they reside. However, drivers of variability in the prevalence of heritable symbionts and their rates of transmission are poorly resolved, particularly across host populations experiencing variable biotic and abiotic environments. To fill these gaps, we surveyed 25 populations of two native grasses (Elymus virginicusandElymus canadensis) across the southern Great Plains (USA). Both grass species host heritable endophytic fungi (genusEpichloё) and can hybridize where their ranges overlap. From a subset of hosts, we characterized endophyte genotype using genetic loci that link to bioactive alkaloid production. First, we found mean vertical transmission rates and population-level prevalence were positively correlated, specifically forE. virginicus. However, both endophyte prevalence and transmission varied substantially across populations and did not strongly correlate with abiotic variables, with one exception: endophyte prevalence decreased as drought stress decreased forE. virginicushosts. Second, we evaluated the potential influence of biotic factors and found that, after accounting for climate, endophyte genotype explained significant variation in symbiont inheritance. We also contrasted populations where host species co-occurred in sympatry vs. allopatry. Sympatry could potentially increase interspecific hybridization, but this variable did not associate with patterns of symbiont prevalence or transmission success. Our results reveal substantial variability in symbiont prevalence and transmission across host populations and identify symbiont genotype, and to a lesser extent, the abiotic environment as sources of this variation.