Intergenerational transfer of ageing: effects of maternal age at breeding on offspring performance

ongoing

Ageing research has primarily focused on somatic deterioration of individuals during their lifetimes; intergenerational effects have been little studied. In this project I address this gap, in the process bringing together currently discrete lines of research from evolutionary ecology and reproductive biology: 1) A large body of research in population biology shows that there can be a negative relationship between parental age at breeding and offspring lifespan. It has been postulated that the magnitude of the effect is exacerbated when offspring experience harsher conditions, particularly in early life. The causes and time-course of this so-called ‘Lansing effect’ are unclear - is it due to higher lifetime frailty of offspring, a faster ageing rate, or both, and how is it affected by the environmental conditions that they face? 2) Telomere loss and mitochondrial dysfunction in somatic cells are two recognised, interconnected, ‘Hallmarks of Ageing’ linked to individual performance and longevity. Experimental work, mostly in fertility research, has shown that the eggs of older mothers frequently have reduced mitochondrial function and shorter average telomere lengths. The life-course outcome of this gametic impairment for the offspring has not been studied. Using the zebra finch, this challenging, high-gain, project tests for the first time the hypothesis that the negative effect of maternal age on offspring performance and ageing rate is due to lifelong, intertwined changes in offspring mitochondrial function and telomere length, and is exacerbated in offspring experiencing increased early life stress. Knowing why, when, and under what conditions maternal age has a negative effect on offspring health and longevity has important implications for our understanding of ageing, life history evolution, reproductive scheduling and mate choice; it also has profound consequences for more applied fields such as reproductive medicine and conservation biology.