Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:This incidence of inbreeding is less than the equilibrium inbreeding coefficient (0.30), indicating an excess of heterozygous plants in the syn-4 population, which may have resulted from
heterozygote advantage due to heterotic selection (Clegg, 1980; Rüter et al., 2000).
Category: