TEMPERATURE, TIME, AND REPTILE EGG WATER EXCHANGE

The effect of incubation temperature (T, degrees C) on the development al rate (R(d), days(-1)) and water exchange of reptile eggs is examine d. The relationship between R(d) and T can be described using the Arrh enius equation. The free energy (E) of this relationship is around 50 kJ.mol(-1), equivalent to a Q(10) of 2, for all the species examined, The data indicate that the R(d)'s of reptile eggs are sensitive to cha nges in T to about the same extent. However, there may be biologically important variation in sensitivity to T. The thermal tolerance range (TTR) of reptile eggs, on the other hand, varies substantially but app ears to be around 10 degrees C or less. Egg water exchange on a rate b asis (M(H2O), mg.day(-1)) is influenced by T and increases by a factor of around 1.9 for every 10 degrees C increase in T. The change in M(H 2O) With T is offset by the increase in R(d) which decreases the incub ation period (I, days) so that total egg water exchange (M(H2O), g)is not influenced by T for eggs whose R(d)'s have Q(10)'s around 1.9. Egg s whose R(d)'s diverge from 1.9 should demonstrate a progressive effec t of T on M(H2O). The M(H2O) and M(H2O) Of eggs is influenced by the t hermal conductivity of the medium in which the eggs incubate. This occ urs because the vapor pressure of the egg during incubation will chang e relative to the vapor pressure of the medium due to the influence of medium thermal conductivity on metabolic self-heating by the egg.