Genetic correlations between host and parasite fitness. Genetic correlations between host seed production (total mass of seeds in milligrams) and parasite transmission (number of successful transmissions). Each symbol represents a unique combination of host line and parasite strain. Symbols are distinguished according to the host line involved in the combination: Gb (red dots), Fin (black dots), Pyr (green dots), Sue (yellow dots), Tch (pink dots), Tsu (blue dots). Solid line: significant regression across the seven strains and control in combination with the host line Gb (y = -0.28x + 97.58; Spearman'rho = 0.81, p-value = 0.015). Dashed lines: non significant regressions for the host lines Fin (y = -0.66x + 61.32; ρ = -0.26, p-value = 0.53), Pyr (y = 0.43x + 17.10; ρ = 0.55, p-value = 0.16), Sue (y = -0.03x + 62.97; ρ = -0.29, p-value = 0.49), Tch (y = -0.07x + 64.15; ρ = -0.24, p-value = 0.57), and Tsu (y = -0.06x + 57.04; ρ = 0.17, p-value = 0.69).