Fig. 1: Unique features of immunity and reproduction in seahorses.

a A species tree showing the evolution of specialized male pregnancy and asplenia traits in the seahorse. During pregnancy, embryos implanted in the “pseudoplacenta” of male seahorses are recognized by the paternal immune system. b Four seahorse species, from the major lineages of seahorses were included in the comparative genomic analyses. Newly sequenced species are indicated in red. Ma, million years ago. c The top 30 KEGG pathways of contracted gene families in seahorses. Categories involved in immunity are colored in brown. The figures were created with BioRender.com. The used map was downloaded from a free world map website (https://www.freeworldmaps.net/outline/maps.html). Source data are provided as a Source Data file.