Are unseen effects of early environment negligible? Threeexamples in great tits (Parus major)

Three case studies failed to demonstrate impacts of early environment or maternal effects on breeding in situationswhere they could have been expected. This leads to a number of methodological questions about the resolving power requiredto detect such impacts, but above all else to the conclusion that maternal effects and homeotic control are opposites. Whenassessing potential maternal effects, one has to consider not only the developmental period in which they occur but also thelater stage of life of concern, because, with age, maternal effects may become less and less important or disappear altogether.The only real measure that there is of the relative importance of early environment and maternal effects is their proportion inphenotypic variance in the traits of interest.

Arie J. van Noordwijk, Acta Zoologica Sinica 52(Supplement): 675-677, 2006