Sex Ratio of Sea Turtles: Seasonal Changes

@article{Mrosovsky1984SexRO,
  title={Sex Ratio of Sea Turtles: Seasonal Changes},
  author={Nicholas Mrosovsky and Sally R. Hopkins-Murphy and James B. Iii Richardson},
  journal={Science},
  year={1984},
  volume={225},
  pages={739 - 741}
}
Sex ratios of hatchling loggerhead turtles Caretta caretta taken from South Carolina and Georgia ranged from no females in nests laid in late May to 80 percent females in those laid in early July; the sex ratio decreased to 10 percent females in nests laid in early August. These seasonal changes are consistent with the role of temperature in directing sexual differentiation in various reptiles. The data have implications for understanding the demography of sea turtles and for their conservation… 

Sex ratios of sea turtles

TLDR
Seasonal sex production profiles (SSPPs) show how similar overall sex ratios can be achieved in dissimilar ways.

Estimating sex ratios of loggerhead turtles in Brazil from pivotal incubation durations

TLDR
The strongly female-biased sex ratio in Brazil is similar to that found previously for loggerheads using beaches in the eastern U.S.A. and suggests that a female- biased hatchling sex ratio may be a feature of loggerhead populations.

Sex ratio of loggerhead sea turtles hatching on a Florida beach

TLDR
The results suggest that in the future, turtles in this area will encounter difficulty in overcoming the feminizing effect of global warming and that biologists should pay more attention to the beaches at the northern end of the loggerhead's nesting range.

Estimating hatchling sex ratios of loggerhead turtles in Cyprus from incubation durations

TLDR
It was estimated that 89 to 99% of the hatchlings produced on Alagadi beach were females, providing a further instance of highly female-skewed sex ratios in loggerhead turtles.

Female-biased sex ratio of immature loggerhead sea turtles inhabiting the Atlantic coastal waters of Florida

TLDR
The sex ratio of immature loggerhead sea turtles, Caretta caretta, inhabiting the Atlantic coastal waters of Florida was investigated, and it is suggested that the sex ratio is significantly female biased.

Molecular evidence of male-biased dispersal in loggerhead turtle juveniles

Sex ratios of two species of sea turtle nesting in Suriname

TLDR
The green turtle and the leatherback nest on the same beach in Suriname and there are seasonal changes in the sex ratio of the hatchlings, with more males being produced during the wetter cooler months of the nesting season and more females during the drier warmer months.

Sex ratios of leatherback turtles: hatchery translocation decreases metabolic heating and female bias

TLDR
Alteration of both primary sex ratios and hatching success is the tradeoff for reducing the risk of death to egg clutches by translocation to a hatchery, and it is a strong indica- tion that hatchery translocation should be used cautiously.

Sex ratio of hatchling loggerhead sea turtles: data and estimates from a 5-year study

TLDR
The present results show that the female-biased sex ratio reported previously by these authors for the 1986 nesting season at this site was not an isolated, atypical event and measurements of beach temperatures at the depth of turtle nests were extended to cover 5 years, which showed temperatures were commonly above the pivotal level.

A micro-environmental study of the effect of temperature on the sex ratios of the loggerhead turtle, Caretta caretta , from Tongaland, Natal

TLDR
The sex ratios of the nests were also dependent on the time of season which is directly related to temperature, and there was no correlation between sex ratios and the physical characteristics of the beach.
...

References

SHOWING 1-10 OF 17 REFERENCES

Temperature-dependent sex determination: current practices threaten conservation of sea turtles.

TLDR
Temperature determines the sex of hatchling green turtles (Chelonia mydas) produced from eggs incubated in a beach hatchery under different temperature regimens, and present conservation practices may be producing all male, all female, or even intersex hatchlings.

Temperature of egg incubation determines sex in Alligator mississippiensis

TLDR
Sex is fully determined at the time of hatching and naturally irreversible thereafter, and depends on the temperature of egg incubation, which constitutes a possible selective evolutionary advantage of temperature-dependent sex determination (TSD) in alligators in that females become large and sexually mature as early as possible.

Sex Determination in Reptiles

  • J. Bull
  • Biology
    The Quarterly Review of Biology
  • 1980
TLDR
Temperature-dependent sex determination (TSD) is common in turtles and has been reported in two lizards and alligators; however, data on TSD are available for few non-turtle species and an attempt is made to deduce their ancestries.

Temperature levels and periods of sex determination during incubation of eggs of Chelydra serpentina

TLDR
Eggs of Chelydra serpentina were shifted during incubation between the female producing temperatures of 20°C or 30°C and the male producing temperature of 26°C, and the stages during which incubation temperature determined sex were stage 14 through stage 16.

Fisheries and WildlIfe Service Project 14-16-002-80-222, final report

  • N. Mrosovsky, Biol. Conserv. 23,
  • 1981

Green turtle (Chelonia mydas (L.)) nesting activity at Aldabra Atoll

TLDR
Green turtle nesting activity was indirectly monitored at the nesting sites at Aldabra by counting turtle tracks and nest pits during 11 months, and the distribution of turtle emergences among nesting beaches suggests that beaches fall into distinct nesting areas that are utilized to different extents.