Multiple paternity in egg clutches of hawksbill turtles (Eretmochelys imbricata)

Joseph, Juanita; Shaw, Paul W.

doi:10.1007/s10592-010-0168-7

Cited by 24 publications

(22 citation statements)

References 17 publications

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“…Our values are in broad agreement with other studies (Kichler et al 1999, Jensen et al 2006, Theissinger et al 2009, Hays et al 2010, Joseph & Shaw 2011, including those for Caribbean hawksbill turtles (Leon & Diez 1999, Geis et al 2003, and with Table 1). The secondary sex ratio can be less female-biased than the primary sex ratio (Kichler et al 1999, Jensen et al 2006, Theissinger et al 2009, Hays et al 2010, Joseph & Shaw 2011, Stewart & Dutton 2011, Wright et al 2012a, 2012b, suggesting differential re cruitment by the sexes to juvenile foraging aggre gations. This could be for 2 reasons: either (1) some female hatchlings recruit elsewhere (sex-biased dispersal; Casale et al 2002); and/or (2) female hatchlings suffer greater mortality than male hatchlings.…”

Section: Sex Ratiossupporting

confidence: 92%

“…It was not possible to estimate whether sampling bias may have affected the estimated sex ratios in this study, but these results should not have been influenced by the presence of any adult female nesting turtles, as we only captured juveniles. Our values are in broad agreement with other studies (Kichler et al 1999, Jensen et al 2006, Theissinger et al 2009, Hays et al 2010, Joseph & Shaw 2011, including those for Caribbean hawksbill turtles (Leon & Diez 1999, Geis et al 2003, and with 14 Fig. 4.…”

Section: Sex Ratiossupporting

confidence: 92%

“…Whether primary sex ratios remain femalebiased in later life stages ('secondary sex ratios') is not well understood, for several reasons: (1) juvenile marine turtles and adult male turtles remain almost exclusively in the ocean, where they are difficult to survey; (2) marine turtles are highly migratory (Godley et al 2008) and thus are rarely located close to their natal area, where the primary sex ratio may be known; and (3) foraging aggregations appear to be comprised of mixed genetic stocks (Bass 1999, Diaz-Fernandez et al 1999, Bowen et al 2007, Mortimer et al 2007, Blumenthal et al 2009, Browne et al 2010. Female-biased primary sex ratios may be maintained at later life stages (Kichler et al 1999, Jensen et al 2006, Theissinger et al 2009, Hays et al 2010, Joseph & Shaw 2011, although some studies suggest that they are not (Wibbels et al 1993, Diez & Van Dam 2003. …”

mentioning

confidence: 99%

“…The potentially relatively high proportion of juvenile male turtles in the present study population suggests a level of resilience against the future effects of climate change. Recent research (Joseph & Shaw 2011, Stewart & Dutton 2011, Wright et al 2012b) has suggested that the operational sex ratios of adult populations of marine turtles could be even less female-biased still.Why a female bias exists in most marine turtle populations is poorly understood and it remains unclear whether it is advantageous in an ecological or evolutionary sense. How might warmer conditions provide for higher fitness for female marine turtles?…”

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confidence: 99%

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Estimating sex ratios in Caribbean hawksbill turtles: testosterone levels and climate effects

Hawkes¹,

McGowan²,

Godley³

et al. 2013

Aquat. Biol.

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Evolutionary theory predicts that male and female offspring should be produced at a 1:1 ratio, but this may rarely be the case for species in which sex is determined during incubation by temperature, such as marine turtles. Estimates of primary sex ratio suggest that marine turtle sex ratios are highly skewed, with up to 9 females per male. We captured juvenile hawksbill turtles Eretmochelys imbricata in waters around Anegada, British Virgin Islands, a regionally important foraging aggregation, and analysed concentrations of plasma testosterone and oestradiol-17β from 62 turtles to estimate sex ratio. There were 2.4 to 7.7 times more females than males. Testosterone concentrations correlated with sampling date and sea surface temperature (SST), with higher con centrations in the late summer when SST was highest, suggesting that assigning sex through threshold values of sex hormones must be carried out cautiously. The sex ratio in the juvenile foraging aggregation around Anegada is more male biased than at other locations, suggesting that turtles at Anegada have resilience against feminising effects of climate change. Future work should (1) integrate the relative contributions of different genetic stocks to foraging aggregations and (2) investigate the annual and seasonal cycles of sex hormones, and differences among individuals and life history stages. KEY WORDS: Marine turtles · Sex ratio · Climate change · HormonesResale or republication not permitted without written consent of the publisher Aquat Biol 18: 9-19, 2013 Skewed sex ratios may be advantageous under specific biological circumstances (e.g. if pa rental investment in the sexes is unequal, if one sex helps their parents or if male siblings compete for mates), but also in some environmental circumstances (Warner & Shine 2008). The Charnov-Bull model (Charnov & Bull 1977) was proposed to ex plain this and has been demonstrated for a lizard species, such that offspring raised in conditions that promote high fitness for females had higher lifetime reproductive success if they were female than male (males were produced by hormonal manipulation at temperatures that usually lead to the development of females; Warner & Shine 2008). Temperature-dependent sex determinationIn marine turtles, sex is determined by the temperature experienced during the middle third of the embryo incubation period (temperature-dependent sex determination [TSD], a type of ESD), where males are produced at lower temperatures and females at higher temperatures (Yntema & Mrosovsky 1980, 1982, Mrosovsky 1988. The majority of research into sex ratios of marine turtles has been carried out on the nesting beach at the hatchling stage, and approaches using the modelled relationship between incubation temperature and sex ratio, as well as incubation duration and sex ratio, have enabled estimation of 'primary' sex ratio for a large number of rookeries (reviewed in Hawkes et al. 2009). Primary sex ratios vary among beaches and within clutches, as well as during the course of a nest...

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Section: Sex Ratiossupporting

confidence: 92%

Section: Sex Ratiossupporting

confidence: 92%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Estimating sex ratios in Caribbean hawksbill turtles: testosterone levels and climate effects

Hawkes¹,

McGowan²,

Godley³

et al. 2013

Aquat. Biol.

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show abstract

“…For male leatherbacks, these adaptations may include the areas they select to intercept females prior to the nesting season. While all species of sea turtle exhibit polyandry (Kichler et al, 1999;Ireland et al, 2003;Jensen et al, 2006;Zbinden et al, 2007;Theissinger et al, 2009;Joseph and Shaw, 2011), multiple paternity in Atlantic leatherback clutches has been observed in low proportions (10-41.7%; Crim et al, 2002;Dutton, 2011, 2014;Figgener et al, 2016). Few instances of inter-nesting mating have been identified in leatherbacks (Figgener et al, 2016), and successive nests laid by most females reveal consistent paternities throughout the nesting season, indicative of sperm storage from mating event(s) occurring prior to the nesting season (Crim et al, 2002;Stewart and Dutton, 2011;Figgener et al, 2016).…”

Section: Inferred Mating Behaviormentioning

confidence: 99%

Pre-nesting Movements of Leatherback Sea Turtles, Dermochelys coriacea, in the Western Atlantic

Bond

James

2017

Front. Mar. Sci.

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Understanding high-use areas for highly migratory species and their movements within these areas may provide insight into behaviors such as foraging and mating. In the Western Atlantic, the leatherback sea turtle, Dermochelys coriacea, has a broad geographic range extending from nesting beaches at low latitudes to foraging areas off the coast of Eastern Canada. Biotelemetry has revealed much about the movements and habitats of leatherbacks. However, the timing and location of leatherback mating behavior remains unclear. We conducted spatial analyses of the movements of reproductive female leatherbacks prior to their first seasonal nesting events. Using kernel density estimates, high-use areas for seven female turtles originally tagged in Canadian waters were revealed from 50% volume contours depicting pre-nesting movements (120 days prior to confirmed nesting events) and inferred mating behavior (45 days prior to confirmed nesting events). All individuals initially remained offshore within a relatively small range of latitude (10-15 • N) before transiting to and residing in coastal waters adjacent to nesting beaches in Colombia (n = 2), Trinidad (n = 3), Guyana (n = 1), and French Guiana (n = 1). Comparison of these movement patterns to those of mature male leatherbacks (n = 12) revealed similarities. Male and female residency within this offshore high-use area may be indicative of prey exploitation prior to the energetically-costly nesting season. While the offshore residency period of three males and one female extended into the interval in which mating is expected to occur, most males and females transited to coastal waters where they resided throughout this period. High-use areas determined through kernel density analysis support and corroborate previous telemetry work indicating that mature male leatherbacks exhibit seasonal residency adjacent nesting beaches for the early portion of the nesting season, presumably to exploit mating opportunities. Fine-scale analyses of fisheries interactions in both coastal and offshore waters and estimation of accompanying mortality rates is required to evaluate fishery threats to this population during the pre-nesting interval.

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Genetic variation, multiple paternity, and measures of reproductive success in the critically endangered hawksbill turtle (Eretmochelys imbricata)

González-Garza

Stow

Teyer

et al. 2015

Ecology and Evolution

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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.

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Multiple paternity in egg clutches of hawksbill turtles (Eretmochelys imbricata)

Cited by 24 publications

References 17 publications

Estimating sex ratios in Caribbean hawksbill turtles: testosterone levels and climate effects

Estimating sex ratios in Caribbean hawksbill turtles: testosterone levels and climate effects

Pre-nesting Movements of Leatherback Sea Turtles, Dermochelys coriacea, in the Western Atlantic

Genetic variation, multiple paternity, and measures of reproductive success in the critically endangered hawksbill turtle (Eretmochelys imbricata)

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