Although males and females rely on each other for reproduction, their precise optima for mating decisions may differ. As pointed out by Bateman (1948) males are under selection to try and obtain more female partners, whereas females should prefer to mate with fewer, but better (male) partners, resulting in a conflict over mating rate. This is particularly true in multi-mating, promiscuous systems with sperm competition, which is the widespread condition among most invertebrates and many vertebrates. Such condition will favour males that are better at persuading females to mate and drive an antagonistic, co-evolutionary arms race within and between the sexes.

We are studying sexual conflict and antagonistic coevolution between males and females in the nematodes Caenorhabditis remanei and Pristionchus uniformis. Nematodes of both species mate multiply with different partners of the opposite sex. Under laboratory conditions population density is high, coinciding with high mating rates.

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Nico Michiels, Nadine Timmermeyer, Karoline Fritzsche