Data from: Dynamic changes in DNA methylation during embryonic and postnatal development of an altricial wild bird

DNA methylation could shape phenotypic responses to environmental cues and
underlie developmental plasticity. Environmentally induced changes in DNA
methylation during development can give rise to stable phenotypic traits
and thus affect fitness. In the laboratory, it has been shown that the
vertebrate methylome undergoes dynamic reprogramming during development,
creating a critical window for environmentally induced epigenetic
modifications. Studies of DNA methylation in the wild are lacking, yet are
essential for understanding how genes and the environment interact to
affect phenotypic development and ultimately fitness. Furthermore, our
knowledge of the establishment of methylation patterns during development
in birds is limited. We quantified genome-wide DNA methylation at various
stages of embryonic and postnatal development in an altricial passerine
bird, the great tit Parus major. While there was no change in global DNA
methylation in embryonic tissue during the second half of embryonic
development, a two-fold increase in DNA methylation in blood occurred
between 6 and 15 d posthatch. Though not directly comparable, DNA
methylation levels were higher in the blood of nestlings compared with
embryonic tissue at any stage of prenatal development. This provides the
first evidence that DNA methylation undergoes global change during
development in a wild bird, supporting the hypothesis that methylation
mediates phenotypic development. Furthermore, the plasticity of DNA
methylation demonstrated during late postnatal development, in the present
study, suggests a wide window during which DNA methylation could be
sensitive to environmental influences. This is particularly important for
our understanding of the mechanisms by which early-life conditions
influence later-life performance. While we found no evidence for
differences in genome-wide methylation in relation to habitat of origin,
environmental variation is likely to be an important driver of variation
in methylation at specific loci.