PhD Studentship: Postreproductive Maternal Care and the Evolution of Sex Differences in Lifespan

Scientific background 

Why do some animals continue to live long after they have stopped reproducing? Classical evolutionary theory predicts that they should not. The force of natural selection on survival declines with age and falls to zero once reproduction ceases, so organisms are expected to die soon after their final reproductive event. Yet substantial postreproductive female lifespan occurs in humans, elephants and several toothed whales, and remains a striking unresolved problem in evolutionary ecology. 

The leading explanation is intergenerational transfer theory, which posits that a female who no longer reproduces can still increase her fitness by provisioning her descendants. If care extends the period over which selection acts on survival, then species where mothers care after reproduction should evolve longer-lived females. This idea is compelling but almost untested, because it has only been studied in protected long-lived mammals which precludes experimental approach. 

We have discovered a system where we can text this theory experimentally. In the nematode Caenorhabditis kamaaina, females that have finished reproducing secrete a nutritive fluid that their larvae eat, and provisioned larvae grow substantially faster. Remarkably, this is also one of the very few Caenorhabditis species in which females outlive males. 

Research methodology 

You will test whether postreproductive maternal care explains sex differences in lifespan. Using an available living collection of wild nematode species, you will measure sex-specific survival, reproduction and postreproductive maternal provisioning across phylogenetically diverse species, and test the prediction that the caring sex is the longer-lived sex. You will then use custom genetic tools developed in our lab to understand the fundamental biology linking postreproductive care and long life. 

Training 

You will gain skills in experimental design, phylogenetic analysis, statistics and coding in R, evolutionary theory, molecular ecology and genetics, scientific writing and presentation. You will receive multi-disciplinary training in evolutionary ecology/biology and in bio-gerontology, thereby increasing opportunities for employability after the PhD. You will participate in career-enhancing external training courses and in-house research discussion groups and journal clubs.    

Person specification 

We seek an enthusiastic, highly motivated individual with a strong interest in evolution, ecology or genetics. 

Funding details 

ARIES studentships are subject to UKRI terms and conditions(opens in a new window). Successful candidates who meet UKRI’s eligibility criteria will be awarded a fully-funded studentship, which covers fees, maintenance stipend (£21,805 p.a. for 2026/27) and a research training and support grant (RTSG). A limited number of studentships are available for international applicants, with the difference between 'home' and 'international' fees being waived by the registering university. Please note, however, that ARIES funding does not cover additional costs associated with relocation to, and living in, the UK, such as visa costs or the health surcharge.