External incubation alters the composition of squamate eggshells

TitleExternal incubation alters the composition of squamate eggshells
Publication TypeJournal Article
Year of Publication1984
AuthorsCox DL, Koob TJ, Mecham RP, Sexton OJ
JournalComparative Biochemistry and Physiology

1. Eggshells of the skink, Eumeces fasciatus, and of the rough green snake, Opheodrys vernalis, contain 28-40% of total shell mass as calcium at oviposition. After incubation, both calcium concentration and content were reduced 17-41%. 2. Protein accounted for 33-65% of shell mass in Eumeces and Opheodrys eggshells at oviposition. Reductions in protein concentration and content from 22-86% following incubation were observed. 3. Comparing amino acid compositions of eggshells collected following oviposition with those collected from the same clutch after hatching reveals similarities among all eggshells excepth those of Eumeces from Michigan which lack desmosine and isodesmosine. 4. Concentrations of desmosines in eggshells from Missouri Eumeces and Michigan Opheodrys appeared to decrease following incubation by 49.7% and 12.2% respectively. 5. Although neither the mechanisms involved in apparent losses of calcium and protein, nor the fate of the mobilized materials are known, possible pathways for mobilization of eggshell constituents are outlined and their pertinence to the physiology of squamate eggs and the evolution of viviparity in reptiles is suggested.