18Maternal age has a negative effect on offspring lifespan in a range of taxa and is hypothesized 19 to influence the evolution of aging. However, the mechanisms of maternal age effects are 20 unknown, and it remains unclear if maternal age alters offspring response to therapeutic 21 interventions to aging. Here, we evaluate maternal age effects on offspring lifespan, 22 reproduction, and the response to caloric restriction, and investigate maternal investment as a 23 source of maternal age effects using the rotifer, Brachionus manjavacas, an aquatic invertebrate. 24 We found that offspring lifespan and fecundity decline with increasing maternal age. Caloric 25 restriction increases lifespan in all offspring, but the magnitude of lifespan extension is greater in 26 the offspring from older mothers. The trade-off between reproduction and lifespan extension 27 under low food conditions expected by life history theory is observed in young-mother offspring, 28 but not in old-mother offspring. Age-related changes in maternal resource allocation to 29 reproduction do not drive changes in offspring fitness or plasticity under caloric restriction in B. 30 manjavacas. Our results suggest that the declines in reproduction in old-mother offspring negate 31 the evolutionary fitness benefits of lifespan extension under caloric restriction. 32 33 KEYWORDS 34 Maternal effects; aging; caloric restriction; evolutionary fitness; maternal investment 35 36 37 38Maternal effects occur when the environment or physiological state of a mother changes the 39 phenotype of her offspring without a corresponding change in genotype. Offspring phenotype 40 may be modified in response to maternal environmental factors including diet, temperature, or 41 exposure to stressors [1][2][3][4][5][6][7][8][9][10][11] . Such maternal effects may be adaptive as in Daphnia and rotifers, in 42 which offspring hatch with protective spines upon maternal exposure to predators [2][3][4][5][6]12 , or as in 43 plants, in which offspring have higher rates of germination and survival when planted in the 44 same high-light or low-light environment as their parent 7,8 . Alternatively, maternal effects may 45 be detrimental as is the case in the negative health outcomes for children due to excessive 46 maternal smoking or alcohol consumption during pregnancy [13][14][15] . We are beginning to 47 understand that maternal effects may be mediated by a variety of epigenetic mechanisms, 48 including direct transmission of maternal proteins, mRNA, lncRNA, miRNA, and modifications to 49 DNA and histones [16][17][18][19][20] . While maternal effects have long been studied and are well known in 50 the ecological literature, there has been a recent rise in interest in maternal effects in the context 51 of human health and aging 21 .
53Maternal age, or the age of a mother at the time her offspring are born, has been shown to have 54 a negative effect on offspring health in a range of taxa [22][23][24][25][26][27][28][29][30][31][32] . A decrea...