Experimental manipulation of egg size and hatchling size in the cobra, Naja naja atra (Elapidae)

We experimentally manipulated eggs of Naja naja atra by partially removing yolk (approximately 15% of the total egg wet mass) from the freshly laid eg gs to test the effect of such a manipulation on hatchling traits. Hatchling s from treated and control eggs took nearly the same time to complete embry onic development. Experimentally treated eggs produced size-reduced hatchli ngs. However, when shell excluded egg mass is statistically kept constant m iniaturized hatchlings had slightly but significantly larger total dry body mass than did their control sibs. Relatively more yolk remained unutilized at the time of hatching in miniaturized hatchlings. Since no significant d ifference in body size or carcass size was found between miniaturized and c ontrol hatchlings when shell-excluded egg mass is kept constant, the differ ence in residual yolk dry mass explained much of their difference in dry bo dy mass. The relative difference in residual yolk dry mass also explained m uch of the difference in lipid mass, energy contents and residual yolk ash mass between miniaturized and control hatchlings.