Global and Planetary Health, University of South Florida, 3720 Spectrum Blvd, Suite 304, Tampa, FL 33620, USA.
Department of Integrative Biology, University of South Florida, 4202 E. Fowler Ave, SCA110, Tampa, FL 33620, USA.
Integr Comp Biol. 2020 Dec 16;60(6):1458-1468. doi: 10.1093/icb/icaa060.
Epigenetic potential, defined as the capacity for epigenetically-mediated phenotypic plasticity, may play an important role during range expansions. During range expansions, populations may encounter relatively novel challenges while experiencing lower genetic diversity. Phenotypic plasticity via epigenetic potential might be selectively advantageous at the time of initial introduction or during spread into new areas, enabling introduced organisms to cope rapidly with novel challenges. Here, we asked whether one form of epigenetic potential (i.e., the abundance of CpG sites) in three microbial surveillance genes: Toll-like receptors (TLRs) 1B (TLR1B), 2A (TLR2A), and 4 (TLR4) varied between native and introduced house sparrows (Passer domesticus). Using an opportunistic approach based on samples collected from sparrow populations around the world, we found that introduced birds had more CpG sites in TLR2A and TLR4, but not TLR1B, than native ones. Introduced birds also lost more CpG sites in TLR1B, gained more CpG sites in TLR2A, and lost fewer CpG sites in TLR4 compared to native birds. These results were not driven by differences in genetic diversity or population genetic structure, and many CpG sites fell within predicted transcription factor binding sites (TFBS), with losses and gains of CpG sites altering predicted TFBS. Although we lacked statistical power to conduct the most rigorous possible analyses, these results suggest that epigenetic potential may play a role in house sparrow range expansions, but additional work will be critical to elucidating how epigenetic potential affects gene expression and hence phenotypic plasticity at the individual, population, and species levels.
表观遗传潜力，定义为通过表观遗传介导的表型可塑性的能力，在范围扩展过程中可能发挥重要作用。在范围扩展过程中，种群可能会遇到相对新颖的挑战，同时遗传多样性降低。通过表观遗传潜力的表型可塑性可能在初始引入或向新地区扩散时具有选择优势，使引入的生物能够快速应对新的挑战。在这里，我们询问了三个微生物监测基因（TLR1B、TLR2A 和 TLR4）中一种表观遗传潜力（即 CpG 位点的丰度）在本地和引入的家麻雀（Passer domesticus）之间是否存在差异。我们利用基于世界各地麻雀种群收集的样本的机会主义方法，发现引入的鸟类在 TLR2A 和 TLR4 中具有更多的 CpG 位点，而在 TLR1B 中则没有。与本地鸟类相比，引入的鸟类在 TLR1B 中失去了更多的 CpG 位点，在 TLR2A 中获得了更多的 CpG 位点，在 TLR4 中失去了更少的 CpG 位点。这些结果不是由遗传多样性或种群遗传结构的差异驱动的，许多 CpG 位点位于预测的转录因子结合位点（TFBS）内，CpG 位点的丢失和获得改变了预测的 TFBS。尽管我们缺乏进行最严格分析的统计能力，但这些结果表明，表观遗传潜力可能在家麻雀范围扩展中发挥作用，但需要进一步的工作来阐明表观遗传潜力如何影响个体、种群和物种水平的基因表达和表型可塑性。
