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:The types of complex genetic interactions between duplicated homeologous loci which are possible after polyploidization are best documented in plants, where allopolyploidy in particular is a pervasive phenomenon (Otto and Whitton 2000; Wendel 2000; Doyle and Egan 2010).
Category: