Our results suggested that the gene cassette diversity of a relatively pristine sampling environment was structured into co-assorting groups, predominantly containing large numbers of cassettes per group. These co-assorting groups consisted of different gene cassettes in stoichiometric relationship. Conservatively, we then attributed co-assorting cassettes to the gene cassette complements of single prokaryote lineages and by implication, to large integron-associated arrays. The prevalence of large arrays in the environment raises new questions about the assembly, maintenance and utility of large cassette arrays in prokaryote populations.
Michael, C. A., & Andrew, N. R. (2010). Co-assortment in integron-associated gene cassette assemblages in environmental DNA samples. BMC Genetics, 11, 75. https://doi.org/10.1186/1471-2156-11-75