Fig. 7

Origin of hard clam IAPs and IAP evolution in different metazoan lineages. a Evolutionary origin of IAPs and organ-specific genes in hard clam. Phylostratigraphic analyses of IAPs (blue), hemolymph-specific (brown), hepatopancreas-specific (red), and gill-specific (turquoise) genes across 10 phylostrata. Only genes for which at least one significant BLAST hit (< e−10) was returned were included. b Expansion and contraction of IAP repertoire across 18 species from different metazoan lineages. Gene gain and loss events are mapped to the species tree, indicated by green and red numbers, respectively. Numbers in yellow boxes indicate the predicted ancestral IAP number of each node. The blue block indicates Bivalvia. Mph, Modiolus philippinarum; Pfu, Pinctada fucata; Cvi, Crassostrea virginica; Afa, Azumapecten farreri; Mme, Mercenaria mercenaria; Rph, Ruditapes philippinarum; Aca, Aplysia californica; Bgl, Biomphalaria glabrata; Lgi, Lottia gigantea; Csq, Chrysomallon squamiferum; Adu, Architeuthis dux; Obi, Octopus bimaculoides; Cte, Capitella teleta; Hro, Helobdella robusta; Ame, Apis mellifera; Dme, Drosophila melanogaster; Hsa, Homo sapiens; Bfl, Branchiostoma floridae; Nve, Nematostella vectensis. c Distribution of IAPs with different domain architectures in 19 species of Metazoa. Asterisk indicates domain architectures expanded in bivalves with a significant corrected P value (P < 0.0001) from Chi-square tests for overrepresentation, using all annotated genes as background