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Having it all: historical energy intakes do not generate the anticipated trade-offs in fecundity

2006; Royal Society; Volume: 273; Issue: 1592 Linguagem: Inglês

10.1098/rspb.2005.3456

1471-2954

Sarah Johnston, Tilman Grune, Liesel Bell, S. J. Murray, Donna M. Souter, Susan S. Erwin, Jon M. Yearsley, Iain J. Gordon, A. W. Illius, I. Kyriazakis, John R. Speakman,

Genetics, Aging, and Longevity in Model Organisms

An axiom of life-history theory, and fundamental to our understanding of ageing, is that animals must trade-off their allocation of resources since energy and nutrients are limited. Therefore, animals cannot ‘have it all’—combine high rates of fecundity with extended lifespans. The idea of life-history trade-offs was recently challenged by the discovery that ageing may be governed by a small subset of molecular processes independent of fitness. We tested the ‘trade-off’ and ‘having it all’ theories by examining the fecundities of C57BL/6J mice placed onto four different dietary treatments that generated caloric intakes from −21 to +8.6% of controls. We predicted body fat would be deposited in relation to caloric intake. Excessive body fat is known to cause co-morbidities that shorten lifespan, while caloric restriction enhances somatic protection and increases longevity. The trade-off model predicts that increased fat would be tolerated because reproductive gain offsets shortened longevity, while animals on a restricted intake would sacrifice reproduction for lifespan extension. The responses of body fat to treatments followed our expectations, however, there was a negative relationship between reproductive performance (fecundity, litter mass) and historical intake/body fat. Our dietary restricted animals had lower protein oxidative damage and appeared able to combine life-history traits in a manner contrary to traditional expectations by having increased fecundity with the potential to have extended lifespans.