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.
Our new paper in BioEssays together with Locke Rowe and Urban Friberg focuses on late-acting deleterious alleles that have small but visible effects in early life. We are making the case that such alleles are important in the evolution of ageing.
Link to the paper or see Publications on this site!
Congratulations to Sara Meurling, an RA in our lab, who won a PhD position to work on frog ecology with Anssii Laurila and Jacob Höglund at our department!
This week we had four new members joining our lab as ERC-funded RAs: Anna Vourlou, Maja Ericsson, Tuuli Larva and Johan Andersson will be joining us for at least a year to work on a series of different projects. Anna and Maja will be working in the fly lab, continuing the work by Felix Zajitschek (now postdoc at GWU in Washington) and Grigorios Georgolopoulous (who is finishing his MSc thesis and leaving to US in the end of April) on the evolution of lifespan extension by dietary restriction. Tuuli and Johan will be working in the nematode lab on mutation accumulation and ageing.