What sex do hermaphrodites signal to attract partners? RENSEIGNEMENTS SUR L’INSTITUTION D'ACCUEIL Laboratoire : LEEC-Laboratoire d'Ethologie Expérimentale et Comparée Responsable : Pr. Heiko G. Rödel Organisme de rattachement : Université Sorbonne Paris Nord Site web : http://leec.univ-paris13.fr RENSEIGNEMENTS SUR L’ENCADRANT Nom, prénom : Lorenzi Maria-Cristina et Elise Jeanne Emploi et fonctions : professeur et technicien Adresse électronique : lorenzi@univ-paris13.fr et eli4.jeanne@gmail.com Téléphone : +33(0)149403260 RENSEIGNEMENTS SUR LE SUJET Typically, animals signal their sex using visual, acoustic, chemical or other signals. Asking a completely novel scientific question, we have just begun to unveil how hermaphrodites signal the two sexes they express. In simultaneous hermaphrodites, each individual produces eggs and sperm at the same time but needs a partner’s sperm to fertilize its eggs. They advertise they are sexually mature hermaphrodites, they are ready to mate…but in which sex? In a way, they need to find a partner ready to play the sexual role opposite to that they are ready to play. Preliminary analyses using the marine worms Ophryotrocha diadema have shown that they communicate their double sex using chemical signals, i.e., compounds that they release in the water. However, the worms that receive the signals respond differently to signals produced by worms ready to mate as females vs those produced by worms ready to mate as males, as if they were signaling “I’m a female” or “I’m a male” depending on the sexual function they are ready to exhibit at any moment. Many questions are still open and need further testing: how rapidly do hermaphrodites change their male vs female signals? What is the effect of the social environment on the signaling (for example, do they change their signal if they are isolated or in a group)? What is the advantage of producing two sexual signals to attract partners, rather than only one? By performing experiments with alive animals, the student will learn how to care for the animals, design experiments, use the stereomicroscope, measure and quantify behaviour and life-history parameters. Finally, he/she will process, analyse and interpret behavioural data. Keywords: behavioral ecology, reproductive strategies, sexual communication DURÉE: 2 mois