Within-season shifts in multiple paternity patterns in mass-nesting olive ridley sea turtles

L González-Cortés,Sg Karam-Martínez,V Islas-Villanueva,E Labastida-Estrada,Ja Montoya-Márquez

doi:10.3354/esr01144

Abstract

Multiple paternity is common to all sea turtle species, but its causes and consequences are hard to ascertain and the behaviors and success of males difficult to observe. This study aims to describe patterns of multiple paternity for olive ridley turtles Lepidochelys olivacea at Playa de Escobilla, an ‘arribada’ (mass-nesting) site on the Mexican Pacific coast with over a million clutches laid each reproductive season. A total of 15 females and their hatchlings were sampled during 3 arribada events which occurred over the 2016-2017 nesting season. Females and hatchlings (N = 329) were genotyped at 5 microsatellite loci, from which we inferred the alleles of 46 contributing males. Multiple paternity was detected in 60% of the analyzed clutches, which were sired by a range of 2 to 7 males. Multiple paternity rates differed significantly across arribada events, suggesting more males achieved fertilizations earlier in the breeding season. Paternal contribution in 6 of the clutches with multiple paternity was skewed towards a single male; the remaining clutches had a homogeneous male contribution. However, our results are based on relatively small within-arribada sample sizes. The frequency of multiple paternity among turtle clutches laid on this arribada beach could be related to the density of breeding individuals in the reproductive patch off Playa de Escobilla, rather than to the nesting population size or female size.

Highlights

In the last century, overexploitation of all sea turtle species has drastically reduced the size of their populations, resulting in their classification as threatened or endangered (Hays 2004)
Olive ridley turtle populations in the Mexican Pacific continue to be threatened by illegal harvesting of eggs and the incidental capture of turtles in shrimp trawl nets, and the species remains classified as endangered by the US federal government (Wallace et al 2010, Rodríguez-Zárate et al 2013)
The present study reports a frequency of 60% multiple paternity (MP), which is lower than the 92% reported by Jensen et al (2006) in Ostional, Costa Rica

Summary

Introduction

Overexploitation of all sea turtle species has drastically reduced the size of their populations, resulting in their classification as threatened or endangered (Hays 2004). In 1990, the Mexican government implemented a ban on all commercial sea turtle fishing (DOF 1990), which has enabled population recovery (Márquez et al 2007). These results are encouraging, the assessment of the global olive ridley populations by the International Union for Conservation of Nature (IUCN) reports a reduction between 31 and 36% in the Publisher: Inter-Research · www.int-res.com. The severe decline in olive ridley turtle individuals in the Mexican Pacific has caused significant loss of genetic variability within the nesting colonies (RodríguezZárate et al 2013). It has been reported that population reduction in some nesting colonies has caused changes in nesting behavior (RodríguezZárate et al 2013)

Objectives

Methods

Results

Conclusion