Photo: R. Bonduriansky. Two neriid males in a fight.
Foteini Spagopoulou has traveled to Sydney, Australia to study how differences in early-life resource acquisition affect age-specific life-histories in male neriid flies in Bonduriansky lab at UNSW. Together with Amy Hooper and Zachariah Wylde, she showed that males developing on good diet develop faster, have early peak in reproductive performance but aged faster and lived shorter than their counterparts developing on poor diet. High-condition males had larger bodies and won more fights than low-condition males.
Because natural selection optimizes fitness rather than longevity,good conditions in early life of a male may result in faster ageing and be detrimental to lifespan.
Martin spend four years as a postdoctoral fellow and researcher in our lab and now he has got the largest grant among those awarded for young investigators this round (4.7 M SEK in total over a period of 4 years).
In his project, Martin will investigate the role of environmental heterogeneity for life history evolution and how growth, development and reproduction affects lifespan and ageing in the nematode worm Caenorhabditis remanei.
This funding will enable Martin to start his own lab as an independent young PI and he will soon start recruiting!
Male nematodes secrete pheromones that accelerate the somatic senescence of potential mates. A very nice new study by Aprison and Ruvinsky shows that this harm most likely is an unintended by-product of the males’ aim to speed up sexual maturation and delay reproductive senescence of future partners.
Urban Friberg and I wrote a commentary on this paper. We also used this opportunity to highlight an important point that it may be not so easy to study the trade-off between lifespan and reproduction using the removal of reproductive system approach, because resources allocated to reproduction may be simply wasted rather than reallocated back to somatic maintenance (see the commentary for the full version of this argument). We used the bucket analogy to illustrate this using a cartoon (see below).
The Expensive Germline and the Evolution of Ageing
Summary: The trade-off between survival and reproduction is the bedrock of the evolutionary theory of ageing. The reproductive system regulates ageing of the soma, and removal of germ cells extends somatic lifespan and increases resistance to a broad variety of abiotic and biotic stresses. The general explanation for this somatic response is that reduced reproduction frees up resources for survival. Remarkably, however, the disruption of molecular signaling pathways that regulate ageing increases lifespan without the obligatory reduction in fecundity, thus challenging the key role of the survival–reproduction trade-off. Here, we review the diverse literature on the costs of lifespan extension and suggest that the current paradigm is overly centered on the trade-off between lifespan and fecundity, often neglecting key aspects of fitness, such as development time, defense against parasites and, in particular, the high costs of germline maintenance. Compromised germline maintenance increases germline mutation rate, which reduces offspring fitness and ultimately can terminate germline proliferation across generations. We propose that future work should incorporate the costs of germline maintenance in the study of ageing evolution, as well as in applied biomedical research, by assessing offspring fitness.
Elisabeth Bolund led this work in sex differences in human lifespan:
Martin Lind led the study showing that males and females pay different costs of lifespan extension by nutrient-sensing inhibitor – rapamycin.
Lind MI, Zwoinska MK, Meurling S, Carlsson H and Maklakov AA (2015) Sex-specific trade-offs with growth and fitness following lifespan extension by rapamycin in an outcrossing nematode, Caenorhabditis remanei.