Figure 2
Presence (+) and absence (ā) of UPKs represented in a simplified phylogenetic tree of chordates. Extinct lineages, hagfish, lungfish and coelacanth lineages have been omitted for simplicity. Reptiles represent Reptiles plus Aves (Sauropsidae). Red asterisks are position in the phylogeny where whole genome duplication events occurred Mya,=1.0 million years. Footnote 1 indicates that there are two forms of this family member, and footnote 2 indicates that there are three members of this family member.