Fig. 1

Study system: the endemic ricefishes of Sulawesi. a Simplified ricefish phylogeny with emphasis on Sulawesi ricefishes. Divergence times and phylogenetic relationships are based on [22]. Red arrows mark the assumed maximum ages for the origin of pelvic brooding in the two respective lineages [22]. b Left panel: Lateral view of females Oryzias eversi (top) and Oryzias nigrimas (bottom). The pelvic brooding Oryzias eversi carries a seven days old cluster of eggs. Eyes and pigments of the developing embryos are visible. Eggs of the transfer brooding species Oryzias nigrimas are about two hours old and will be deposited within the next few hours. The pelvic fins of female O. nigrimas are visibly shorter compared to O. eversi. Right panel: Brooding female (top) and male (bottom) of Adrianichthys oophorus