Is there a latitudinal diversity gradient for symbiotic microbes? A case study with sensitive partridge peas

Mutualism is thought to be more prevalent in the tropics than temperate zones and may therefore play an important role in generating and maintaining high species richness found at lower latitudes. However, results on the impact of mutualism on latitudinal diversity gradients are mixed, and few empirical studies sample both temperate and tropical regions. We investigated whether a latitudinal diversity gradient exists in the symbiotic microbial community associated with the legume Chamaecrista nictitans. We sampled bacteria DNA from nodules and the surrounding soil of plant roots across a latitudinal gradient (38.64 °N to 8.68 °N). Using 16S rRNA sequence data, we identified many non-rhizobial species within C. nictitans nodules that cannot form nodules or fix nitrogen. Species richness increased towards lower latitudes in the non-rhizobial portion of the nodule community but not in the rhizobial community. The microbe community in the soil did not effectively predict the non-rhizobia co...

互利共生（Mutualism）通常被认为在热带地区较温带地区更为普遍，因此可能在产生并维持低纬度地区较高的物种丰富度方面发挥重要作用。然而，现有关于互利共生对纬度多样性梯度影响的研究结果并不一致，且鲜有实证研究同时覆盖温带与热带区域。本研究针对与豆科植物含羞草山扁豆（Chamaecrista nictitans）共生的微生物群落，探究其是否存在纬度多样性梯度。我们在横跨38.64°N至8.68°N的纬度梯度范围内，采集了植物根瘤及周边根系土壤中的细菌脱氧核糖核酸（DNA）。借助16S核糖体RNA（16S rRNA）测序数据，我们在含羞草山扁豆的根瘤中发现了诸多无法形成根瘤或固氮的非根瘤菌物种。根瘤群落中非根瘤菌组分的物种丰富度随纬度降低而升高，但根瘤菌群落并未呈现该趋势。土壤中的微生物群落无法有效预测非根瘤菌的共...