Abstract
Schistosomes are the causative agents of schistosomiasis, a Neglected Tropical Disease affecting over 230 million people worldwide. Additionally to their major impact on human health, they are also models of choice in evolutionary biology. These parasitic flatworms are unique among the common hermaphroditic trematodes as they have separate sexes. This so-called « evolutionary scandal » displays a female heterogametic genetic sex-determination system (ZZ males and ZW females), as well as a pronounced adult sexual dimorphism. These phenotypic differences are determined by a shared set of genes in both sexes, potentially leading to intralocus sexual conflicts. To resolve these conflicts in sexually selected traits, molecular mechanisms such as sex-biased gene expression could occur, but parent-of-origin gene expression also provides an alternative. In this work we investigated the latter mechanism, i.e. genes expressed preferentially from either the maternal or the paternal allele, in Schistosoma mansoni species. To this end, transcriptomes from male and female hybrid