Multiple paternity in the East Pacific green turtle (Chelonia mydas) from the Pacific coast of Mexico

•East Pacific green turtle has variation on multiple paternity over a season.•Frequency of multiple paternity in the East Pacific green turtle was 75%.•From 2 to 5 males can be detected analyzing 7-20 hatchlings of a single nest.•One male can sire offspring of consecutive nests of single female in one season.

Multiple paternity is a common phenomenon among marine turtles. This behavior is associated with male density and sperm storage in marine species, but no fitness benefits have been detected in offspring from multiple-sired nests. The green turtle (Chelonia mydas) has been commonly studied around the world. Evidence of multiple paternity in C. mydas ranges from almost zero to 100%. In this study, we investigate multiple paternity in C. mydas using microsatellites to determine the number of males that fertilized clutches during two nesting seasons at a high-density nesting beach in the west coast in Michoacán state, Mexico. The minimum number of eggs per nest needed to detect multiple paternity and the number of males involved in fertilization were also assessed. The results indicated that multiple paternity occurred in up to 75% of the nest samples. In addition, the minimum number of eggs per nest required to detect multiple genotype contributions was 6.66 for two fathers, 12.44 for three fathers, 15.49 for four fathers and 20.24 for five fathers. Females fertilized their eggs using contributions from different males between and within clutches during the nesting season. This behavior led to a multiple paternity pattern, which can be advantageous during different life stages but not necessarily during early life.