Figure 1: Types of genetic duplications. (a) Shows an autochthonous duplication, which can happen either through tandem duplication, segmental duplication, chromosomal duplication, genome duplications, or retro-transposition. (b) Shows gene family expansion through HGT. Following the divergence of two lineages orthologous genes diverge in sequence and possibly in function. These orthologs can be brought together in a single genome through HGT or allopolyploidization (c). The scenarios depicted in (c) and (b) explain an apparent duplication through reticulated evolution.