Low water vapor conductance of hard‐shelled eggs of the gecko lizards Hemidactylus and Lepidodactylus

Abstract

AbstractTypical reptilian eggs require a moist substrate for normal development and undergo a water loss across the shell in dry air many times that of avian eggs. Certain geckos lay hard‐shelled, calcareous eggs, often in arboreal locations, that have been postulated to be truly cleidoic. It has been demonstrated here for the first time that such hard‐shelled gecko eggs do in fact have extremely low rates of evaporative water loss in dry air. Indeed, values of water vapor conductance are considerably lower than those predicted for avian eggs of the same mass. Normal embryonic development apparently does not require absorption of liquid water from the environment. It is quite likely that these geckos represent an independent evolution of the cleidoic egg, separate from the reptilian lineage that led to the birds.