Fig. 3

Genetic relationship between host mussels and their thiotrophic endosymbionts from the hybrid zone at 23°S. The left panel represents genetic assignments of eight individual mussels to five categories: blue = northern parental (B. thermophilus); red = southern parental (B. antarcticus), black = F1 hybrid; white = F2 hybrid, light blue = northern backcross hybrid, and pink = southern backcross hybrid [36]. Vertical lines mark 0.75 and 0.90 values of posterior probabilities for the assignments. The right panel represents the corresponding symbiont type of each host mussel. Dark blue color-codes for northern symbiont type (EPR) and orange color codes for southern symbiont type (PAR)