Condition for detecting a conversion event. Suppose that conversion, outgroup speciation, and duplication events occurred x, y, and z years ago, respectively (x <y <z), and the events formed regions A1 and A2 in primary species A and regions B1 and B2 in the outgroup species B (note that in this type of tree, the nodes represent homologous sequence segments). We observe that the paralogous sequences A1 and A2 are more similar than would be expected without a conversion, i.e. the evolutionary distance between them is less than that between orthologs A1 and B1, though the distance between paralogs B1 and B2 is greater.
Song et al. BMC Evolutionary Biology 2011 11:226 doi:10.1186/1471-2148-11-226