Fig. 1

IAP expansion across Mollusca shows complex species-specific expansion and cross-species conservation. IAP proteins were identified using HMMER and Interproscan across 10 molluscan annotated genomes (Aplysia californica, Biomphalaria glabrata, and Elysia chlorotica (Heterobranchia), Crassostrea virginica and Crassostrea gigas (Ostreida), Lottia gigantea (Patellogastropoda), Mizuhopecten yessoensis (Pectinida), Octopus bimaculoides and Octopus vulgaris (sinensis) (Octopoda), and Pomacea canaliculata (Coengastropoda), Table 1) and patterns of IAP protein expansion were assessed by generating phylogenetic trees. A Phylogenetic tree of studied mollusc genomes produced by OrthoFinder with a heatmap depicting the number of IAP genes in each species. IAPs were most expanded in B. glabrata, least expanded in Octopus spp., and more expanded in C. virginica than C. gigas. B Phylogenetic tree of the longest isoform IAP transcript sequences across 10 mollusc species produced with RAxML and aligned with MAFFT. Sequences are named with shortened RefSeq product names or gene locus identifiers for those annotated as “uncharacterized protein LOCX”. Node shapes indicate bootstrap support (circle = 90–100, upward triangle = 70–89, downward triangle = 50–69) and numbers indicate clusters of interest referred to in text. IAP proteins clustered mainly by species-relationship but presented species-specific clusters, with B. glabrata having the largest (cluster 1). BIRC6-like (cluster 2) and BIRC5-like (cluster 3) proteins from all studied molluscan species clustered closely together, suggesting potential cross-species conservation