Figure 1.

Relationships between drift load estimated via heterosis in outcrossing populations of A. lyrata and expected heterozygosity, H_E, and local A. lyrata density. Drift load was revealed by experimental crosses and assessment of multiplicative performance I over 4 years (a), germination (b), pathogen resistance (c) and flower production during all 4 years (d). Contour plots illustrate the models fitted in Table 2; the contour interval is the model-estimated value of drift load, as defined in Materials and methods. Symbols represent populations, with the diameter of the bubble proportional to ln(drift load+constant).