Speckled and plain regions of avian eggshells differ in maternal deposition of calcium and metals: A hitherto overlooked chemical aspect of egg maculation

Abstract

ABSTRACT Although it has been strongly implied that studies on structural function might resolve certain conflicting theories regarding the huge variability of coloration in avian eggs, including maculation, the fundamental physiological question about the functional role of eggshell speckling in the maternal deposition of micronutrients into maculated (pigment spots) and plain (unpigmented) eggshell regions remains largely unanswered. We measured (within the same egg) the concentrations of 2 micronutrients, the staple components of avian eggshells (calcium and magnesium), and 6 trace elements (copper, manganese, iron, cobalt, cadmium, and lead) in maculated (a superficial layer of brown pigment) and unpigmented areas of eggshells in 2 groups of Japanese Quail (Coturnix coturnix japonica) eggs representing 2 extremes of eggshell coloration: those with darker eggshells and more extensive pigment spots vs. those with bright eggshells and small, more clearly demarcated pigment spots. We found evidence that t...