Simulated bacterial infection induces different changes in DNA methylation between introduced and native house sparrows Passer domesticus

DNA methylation, which can change within-individuals over time and regulate gene expression, is important to many aspects of avian biology. It is particularly important in avian responses to various stressors associated with introductions, such as infection and environmental changes. However, it remains unclear whether native and introduced bird populations differ in their epigenetic responses to stressors, and how DNA methylation may contribute to the success of non-native populations because of the limited availability of epigenetic studies. To address this knowledge gap, we used epiRADseq to investigate changes in DNA methylation within-individual house sparrows Passer domesticus prior to and eight hours after a simulated bacterial infection. We compare wild-caught house sparrows from introduced populations with those from native populations, assessing the number of genomic locations that exhibit changes in methylation, the magnitude of those changes, and the variance among individuals. Our results show that individuals from introduced populations experience more widespread changes in DNA methylation, with greater magnitude and higher variance, compared to their counterparts from native populations. These findings suggest that DNA methylation plays a significant role in an individual's response to infection. They also indicate that individuals from introduced populations may exhibit distinct epigenetic responses compared to their native counterparts, consistent with the concept of epigenetic buffering.