a,b, Increasing fungal ITS copy number (a) and increasing cbhI gene copy number (b) with declining catchment glacier cover. c,d, Increase in mean tensile-strength loss with increasing fungal ITS copy number (c) and with increasing cbhI gene copy number (d). For river sites in the Alaska Boundary Range, no amplification was detected. The sample numbers vary because the fungal ITS and cbhI gene did not amplify at all river sites. DD, degree-days; F, F-statistic. The solid lines represent generalized linear models (GLMs) or generalized additive models (GAMs), and the dashed lines represent 95% confidence intervals.