Abstract
The cumulative effects of non-lethal stressors on the health of biodiversity are a primary concern for conservation, yet difficulties remain regarding their quantification. In mammals, many stressors are processed through a common stress-response pathway, and therefore epigenetic changes in genes of this pathway may provide a powerful tool for quantifying cumulative effects. As a preliminary assessment of this approach, we investigated epigenetic manifestations of stress in two killer whale populations with different levels of exposure to anthropogenic stressors. We used bisulfite amplicon sequencing to compare patterns of DNA methylation at 25 CpG sites found in three genes involved in stress response and identified large differences in the level of methylation at two sites consistent with differential stress exposure between Northern and Southern Resident killer whale populations. DNA methylation patterns could therefore represent a useful method to assess the cumulative effects of non-lethal stressors in wildlife.
Highlights
The cumulative effects of non-lethal stressors on the health of biodiversity are a primary concern for conservation, yet difficulties remain regarding their quantification
Using amplicon sequencing of sodium bisulfite treated DNA extracted from biopsy samples of skin from free swimming killer whales, we identified percent methylation for CpG sites in the promoter region of three genes known to be key players in stress response: brain derived neurotrophic factor (BDNF), corticotropin releasing factor (CRF) and NR3C1; as well as ACTB (β-actin)—a gene commonly used as a control as it regulates components of the c ytoskeleton[37] (Figure S1)
Neither age nor sex had appreciable effects on methylation patterns, with the mean of the posterior distributions falling close to zero (Fig. 2a), confirming that methylation of the targeted CpG sites does not change with age or under the different hormonal exposures experienced across the two sexes
Summary
The cumulative effects of non-lethal stressors on the health of biodiversity are a primary concern for conservation, yet difficulties remain regarding their quantification. We used bisulfite amplicon sequencing to compare patterns of DNA methylation at 25 CpG sites found in three genes involved in stress response and identified large differences in the level of methylation at two sites consistent with differential stress exposure between Northern and Southern Resident killer whale populations. DNA methylation patterns could represent a useful method to assess the cumulative effects of non-lethal stressors in wildlife. Lethal threats such as directed hunting or incidental mortality (e.g., due to habitat loss or accidental mortality such as bycatch) represent the largest threats to global b iodiversity[1,2,3], there is increasing recognition that non-lethal threats are compromising the viability of many populations, when experienced in combination and/or when they have synergistic effects[4,5,6]. Controlled laboratory experiments on mice and rats have identified changes in methylation patterns in response to stressors in genes in the Scientific Reports | (2021) 11:16822
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
