An end to male pregnancy

Male pregnancy is restricted to seahorses, pipefish and their relatives — the family Syngnathidae — in which the young are nurtured in the male’s brood pouch. These broody males do more than just act as a passive incubator, as Kimberly Paczolt and Adam Jones show in new research. It is already known that the brood pouch is a complex structure that nurtures the developing young. But as it nurtures, so can it weed. In the Gulf pipefish Syngnathus scovelli, males are shown to be capable of selectively aborting embryos from females perceived as less attractive, saving resources for more promising prospects encountered later. This is the only known example of postcopulatory sexual conflict in a sex-reversed species. [Letter p. 401; News & Views p. 364; www.nature.com/podcast]