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.