Study

Temperature-dependent sex determination and hatching success in the gopher tortoise (Gopherus polyphemus)

  • Published source details Burke R.L., Ewert M.A., McLemore J.B. & Jackson D.R. (1996) Temperature-dependent sex determination and hatching success in the gopher tortoise (Gopherus polyphemus). Chelonian Conservation and Biology, 2, 86-88.

Actions

This study is summarised as evidence for the following.

Action Category

Alter incubation temperatures to achieve optimal/desired sex ratio: Tortoises, terrapins, side-necked & softshell turtles

Action Link
Reptile Conservation
  1. Alter incubation temperatures to achieve optimal/desired sex ratio: Tortoises, terrapins, side-necked & softshell turtles

    A replicated, randomized study in 1992 in a laboratory in the USA (Burke et al. 1996) found that altering the incubation temperature of gopher tortoise Gopherus polyphemus eggs resulted in different sex ratios of hatchlings. Cooler incubation temperatures produced more males, whereas warmer temperatures produced more females (26°C: 4 male, 0 female; 29°C: 3 male, 1 female; 32°C: 0 male, 4 female). Overall hatching success was 77% (20 of 26 eggs), and incubation period was longer at lower temperatures (26°C: 115 days; 29°C: 97 days; 32°C: 86 days). In June 1992, four wild-caught tortoises were induced with oxytocin and the 26 eggs produced were randomly assigned to the 26, 29 or 32°C treatment. Eggs were placed in containers of moist vermiculite, and every two weeks containers were rotated, and water levels topped up. After 10 months in captivity 17 hatchlings had died and 13 of these were sexed successfully.

    (Summarised by: William Morgan)

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