Maternal age at birth shapes offspring life‐history trajectory across generations in long‐lived Asian elephants

Abstract

Advanced maternal age at birth can have pronounced consequences for offspring health, survival and reproduction. If carried over to the next generation, such fitness effects could have important implications for population dynamics and the evolution of ageing, but these remain poorly understood. While many laboratory studies have investigated maternal age effects, relatively few studies have been conducted in natural populations, and they usually only present a “snapshot” of an offspring's lifetime. In the present study, we focus on how maternal age influences offspring life‐history trajectories and performance in a long‐lived mammal. We use a multigenerational demographic dataset of semi‐captive Asian elephants to investigate maternal age effects on several offspring life‐history traits: condition, reproductive success and overall survival. We show that offspring born to older mothers display reduced overall survival but higher reproductive success, and reduced survival of their own progeny. Our results show evidence of a persistent effect of maternal age on fitness across generations in a long‐lived mammal. By highlighting transgenerational effects on the fitness of the next generation associated with maternal age, the present study helps increase our understanding of factors contributing to individual variation in ageing rates and fitness.

Taming age mortality in semi-captive Asian elephants

“…Calves of older mothers could also be expected to show higher mortality for this reason, due to the senescence of older www.nature.com/scientificreports www.nature.com/scientificreports/ females 46 , however we found that calves born to older mothers experienced slightly higher mortality during specific taming ages, but this effect was not significant. This is consistent with recent findings in this population that maternal age does not necessarily dictate survival in the first five years, but rather their overall lifespan 47 .…”

Reproductive senescence and parental effects in an indeterminate grower

“…diet, temperature, pathogen prevalence) on offspring performance has been described for a long time (Curley, Mashoodh, & Champagne, 2011;Mousseau, 1998) but an increasing number of studies have revealed that parental age can also negatively impact F I G U R E 2 Breeding rate according to individual's age offspring survival (Fox, Bush, & Wallin, 2003;Priest, Mackowiak, & Promislow, 2002) and reproduction (Bouwhuis, Charmantier, Verhulst, & Sheldon, 2010;Ducatez et al, 2012;Lippens, Faivre, Lechenault, & Sorci, 2017;Priest, Roach, & Galloway, 2008;Schroeder, Nakagawa, Rees, Mannarelli, & Burke, 2015). For instance, in Asian elephants (Elephas maximus), older mothers produce offspring with impaired survival (Reichert et al, 2019) and in the rotifers Brachionus manjavacas, maternal age negatively affects offspring survival and reproduction (e.g. egg quality) (Bock, Jarvis, Corey, Stone, & Gribble, 2019).…”

Faecal Glucocorticoid Metabolites and H/L Ratio Are Related Markers of Stress in Semi-Captive Asian Timber Elephants

“…To investigate how our two correlates of stress co-varied with between-and within-individual variation in body condition, body weight data (as a proxy for condition) from 2016 to 2018 was collected simultaneously with the blood and faecal sample collection using an Eziweigh 3000 ® scale, capable of weighing up to 9000 kg to the nearest 10 kg. To control the effect of age on elephant's size, and following previous work (e.g., [52,53]), we calculated and used standardised weights as dependent variables (on average two measurements per individual with a range of one to eight measurements per individual), so that we could measure the changes in body weight relative to the typical weight at a given age. These standardised weights were obtained by dividing an individual's measured weight by the predicted weight at that age, as obtained from von Bertalanffy growth curves from this population (presented in [53]).…”