Inheritance of Egg-Colour in the ‘Parasitic’ Cuckoos

Abstract

PROF PUNNETT¹ has suggested that Prof. Wynne-Edwards' ingenious hypothesis² for explaining how the gentes of parasitic cuckoos may be kept distinct despite their promiscuous orpolyandrous matinghabits could be replaced by the assumption that it is the Y-chromosome of the mother which carries the factor assumed to determine the gens to which the offspring belong. It is not clear that such an alternative theory has any advantages over the original one (though it might have, were the degree of mimicry invariable). It seems slightly less plausible genetically owing to the paucity of known Y-chromosome genes, and has the distinct disadvantage that it involves the offspring all belonging to the same gens as the mother; the “mechanismprovided for stabilising the population by damping the fluctuations caused by the host species” which is inherent in Prof. Wynne-Edwards' theory is therefore lacking.