Trivers (1972) suggested that the large investment in offspring makes females a resource that males compete for. This idea, that male reproductive success (RS) is primarily mediated by the number of mates, has been empirically supported in polygamous species. However, variation in reproductive qualities of females (i.e., clutch or litter size, reproductive frequency and investment) can also influence male RS. For example, in some iteroparous species, the combined effects of female reproductive frequency and the use of sperm from the same male (through re-mating or use of stored sperm) in subsequent reproductive events can have a substantial influence on male RS. Further, the reproductive strategy may also be influenced by social organisation. Therefore, documentation of the relative contributions of social organisation, mate number and mate quality to male RS are necessary to interpret mating tactics in many species.

The European pond turtle Emys orbicularis is a small freshwater turtle of conservation concerns. Monitoring its social organisation, mating events and reproduction output is challenging in the wild due to its cryptic biology, mostly aquatic ecology, nocturnal nesting behaviour and sperm storage capacities. We propose to overtake this challenge by implementing an approach combining direct phenotypic and behavioural observations (skin colour patterns, mating and nesting events), animal-borne inter-individual proximity data-loggers (social structure of the population) and genetic fingerprinting (paternity tests on collected clutches held in artificial incubators). This research will be conducted in a small population of 23 adult individuals of known identity and DNA profile behaving freely in the outdoor captive facility of the conservatory husbandry of the research station Petite Camargue Alsacienne, Saint-Louis, France.