Abstract
The Yucatán Peninsula in Mexico contains some of the largest breeding groups of the globally distributed and critically endangered hawksbill turtle (Eretmochelys imbricata). An improved understanding of the breeding system of this species and how its genetic variation is structured among nesting areas is required before the threats to its survival can be properly evaluated. Here, we genotype 1195 hatchlings and 41 nesting females at 12 microsatellite loci to assess levels of multiple paternity, genetic variation and whether individual levels of homozygosity are associated with reproductive success. Of the 50 clutches analyzed, only 6% have multiple paternity. The distribution of pairwise relatedness among nesting localities (rookeries) was not random with elevated within-rookery relatedness, and declining relatedness with geographic distance indicating some natal philopatry. Although there was no strong evidence that particular rookeries had lost allelic variation via drift, younger turtles had significantly lower levels of genetic variation than older turtles, suggesting some loss of genetic variation. At present there is no indication that levels of genetic variation are associated with measures of reproductive success such as clutch size, hatching success, and frequency of infertile eggs.
Highlights
Wide-ranging, migratory species face multiple, often anthropogenic, challenges to their survival because they usually occupy different habitats to feed, rest, and breed (CMS 1983)
We evaluated a total of 50 clutches, including some successive clutches, from 41 different females located at six different rookeries on the Yucatan Peninsula (Fig. 2)
Genetic variation was similar within each of the six rookeries examined on the Yucatan Peninsula, Mexico
Summary
Wide-ranging, migratory species face multiple, often anthropogenic, challenges to their survival because they usually occupy different habitats to feed, rest, and breed (CMS 1983). Sea turtles are considered highly migratory and many species undergo transoceanic migration (Bowen et al 1995; Bolten et al 1998), occupy different habitats depending on their life stage (Spotila 2004), and typically show high site fidelity for egg laying and breeding location (Bowen and Karl 2007). Each of these characteristics render marine sea turtles especially vulnerable to anthropogenic impacts (Lutcavage et al 1997). If these impacts reduce connectivity and population sizes, inevitably, genetic variation will be lost and this elevates the risk of extinction (Spielman et al 2004) through loss of evolutionary potential and inbreeding depression (Frankham et al 2002)
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