Mating behaviour and relatedness
Finally, none of the deduced mating behaviour, i.e mating with multiple partners, breeding more frequently, or having a higher share of paternity in multipaternity clutches was correlated with a change in the relatedness compared to the relatedness of all reconstructed couples (Figure 6). T-test p-values on the mean relatedness ranged from 0.16 to 0.5 (Table 3). However, fathers that were dominant in multipaternity clutches were consistently more related to the female than to the other father, although that comparison involved only 8 pairs and the difference was not significant with the t-test (p-value: 0.180, Table 3). Relatedness of couples with the dominant father ranged between 0.044 and 0.391 (mean r= 0.252), while relatedness with the non-dominant father ranged between -0.180 and 0.212 (mean r= 0.130).
Discussion
The present parentage analysis on the green turtle nesting population of Tetiaroa allowed for the genotype of 31 females and 27 males to be rebuilt from the genotype of 443 hatchlings from 105 nests, leading to an OSR of 0.87. The highly conservative thresholds we adopted in the analysis process accounted for the small number of males and females retained, which should be interpreted as a minimal number of breeders rather than the real number. As a principle, we favoured type II errors, assuming that reconstructed males and females are real and provide certainty in the following analysis. Nonetheless, patterns related to the mating system of this green turtle population emerged. First, the relatedness of couples was higher than expected by random mating, coupled with significant Fis , regardless of the mating behaviour considered. Neither the multipaternity nor the global relatedness was correlated with the fitness parameters in the clutches. Second, a low level of multipaternity was observed, and individuals showed some plasticity in their mating behaviours. Noticeably, both males and females appeared able to reproduce annually. Within a single season, we discover that females can lay several clutches over short time intervals, and males can sire several females, both before and during the nesting season. All of these outcomes are quite new in the depiction of green turtle reproductive behaviour and features.