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:Both phylogenies show bindin alleles of each Neotropical species of Echinometra clustered into reciprocally monophyletic units, but in the McCartney and Lessios (2004) phylogeny,
the sister clade of E. lucunter alleles consisted of alleles of E. vanbrunti.
Category: