Embryonic Growth and Calcium Mobilization in Oviposited Eggs of the Scincid Lizard, Eumeces fasciatus

Female Eumeces fasciatus from a population in eastern Oklahoma oviposited eggs that had progressed to developmental Stage 30. Under controlled incubation conditions, these eggs rapidly gained water following oviposition. Embryonic growth, measured as increases in dry mass and calcium mass, was moderate for the initial 15 days (Stage 37/38 embryos) of the interval of incubation following oviposition (x̄ = 26.5 days). The interval from Day 7 (Stage 34/35) to Day 21 (Stage 40) was characterized by embryonic calcium gains that corresponded to yolk calcium losses. Following Day 21, calcium in total egg contents (yolk plus embryo) increased, yet yolk calcium mass continued to decrease. Thus, embryos relied on calcium from yolk reserves during early stages of differentiation and growth, but mobilized calcium from eggshells during the final growth phase. Approximately 39% of total hatchling calcium was obtained from eggshells. The pattern of postovipositional embryonic growth of E. fasciatus does not support hypotheses that oviposition among squamate reptiles is timed immediately to precede an interval of rapid embryonic growth.