Sex-specific changes in autosomal methylation rate in ageing common terns
Britta S. Meyer1, Maria Moiron2, Calvinna Caswara3, William Chow4, Olivier Fedrigo5, Giulio Formenti5, Bettina Haase5, Kerstin Howe4, Jacquelyn Mountcastle5, Marcela Uliano-Silva3,4§,6, Jonathan Wood4, Erich D. Jarvis5, 7, Miriam Liedvogel*1,2§, Sandra Bouwhuis*2
*equal contributions
§current address
1 Max Planck Institute for Evolutionary Biology, Behavioural Genomics; August-Thienemann-Str. 2; 24306 Plön; Germany
2 Institute of Avian Research; An der Vogelwarte 21; 26386 Wilhelmshaven; Germany
3 Berlin Center for Genomics in Biodiversity; Königin-Luise-Straße 2-4 Gartenhaus; 14195 Berlin Germany
4 Wellcome Sanger Institute, Wellcome Genome Campus, Cambridge CB10 1SA, UK
5 The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
6 Department of Evolutionary Genetics, Leibniz Institute for Zoo and Wildlife Research (IZW)
7Howard Hughes Medical Institute, 4000 Jones Bridge Rd, Chevy Chase, MD 20815
Corresponding author: bmeyer@evolbio.mpg.de

Abstract

Senescence, an age-related decline in survival and/or reproductive performance, occurs in species across the tree of life. Molecular mechanisms underlying this within-individual phenomenon are still largely unknown, but DNA methylation changes with age are among the candidates. Using a longitudinal approach, we investigated age-specific changes in autosomal methylation of common terns, relatively long-lived migratory seabirds known to show senescence. We collected blood at 1-, 3- and/or 4-year intervals, extracted DNA from the erythrocytes and estimated autosomal DNA methylation by mapping Reduced Representative Bisulfite Sequencing reads to a new reference genome. We found autosomal methylation levels to decrease with age within females, but not males, and no evidence for selective (dis)appearance of birds of either sex in relation to their methylation level. Moreover, although we found positions in the genome to consistently differ in their methylation levels, individuals did not show such strong consistent differences. These results pave the way for studies at the level of genome features or specific positions, which should elucidate the functional consequences of the patterns we observe, and how they translate to the ageing phenotype.
Keywords: aging, avian senescence, epigenetics, ontogeny, RRBS,