Selected ¹²C/¹³C and ¹⁴N/¹⁵N abundance ratios as a function of time in simulations S1 to S3, labeled in the top right panel. The dashed black line in each panel indicates either the assumed elemental ¹⁴N/¹⁵N ratio (440) or the elemental ¹²C/¹³C ratio (68), except for C₃ for which a ratio of 34 is used as our model does not distinguish between CC¹³C and ¹³CCC. Solid and dashed colored lines represent simulations without and with the C+N exchange reactions (Table 2), respectively. In the case of the ¹²C/¹³C ratios, these lines overlap almost perfectly.