Tag Archives: ageing

New paper: Food supply – not ‘live fast, die young’ mentality – makes male crickets chirpy

I have a new paper out in the journal Functional Ecology, entitled ‘Mating opportunities and energetic constraints drive variation in age-dependent sexual signalling‘. This is work from my PhD with Luc Bussière at Stirling, along with collaborators from the University of Exeter’s Cornwall campus (where I’m currently based).

We used dietary manipulations as well as manipulation of potential mate availability to investigate how male sexual signalling changes with current budget and previous expenditure. We found some cool results about what causes variation in age-dependent sexual signalling – these have implications for ‘honesty’ in sexual displays, and are also a nice reminder that there are simpler explanations than we (as humans, who love seeing patterns in the noise) often cling to.

Our paper also includes a nice example of using ‘zero-altered’ statistical models, enabling us to partition out effects on why males call from the effects on how long they call.

You can find the paper here, or email me for a PDF if you don’t have access to the journal.

Alternatively, the press office at Exeter put together a nice press release, which I’ve pasted below:


 

Shedding a few pounds might be a good strategy in the human dating game, but for crickets the opposite is true.

Well-fed male crickets make more noise and mate with more females than their hungry counterparts, according to research by the universities of Exeter and Stirling.

It has long been believed that males who acquire ample food can adopt a “live fast, die young” strategy – burning energy by calling to attract females as soon as they are able, at the expense of longevity – while rivals with poorer resource budgets take a “slow and steady” approach, enabling them to save resources and take advantage of their savings later in the season.

But the researchers found that increased diet – rather than any strategic decision by the cricket – led the best-provisioned crickets to chirp for longer. This had no noticeable cost to their lifespan.

Meanwhile hungrier males not only signalled less – meaning fewer female visitors – but also died younger.

Senior author Dr Luc Bussière, of the University of Stirling, said the findings offered a “simpler alternative” to understanding the behaviour of crickets.

“While it was intriguing to think that males might foresee and plan for their future reproductive prospects by strategically staying quiet, what our experiment suggests is actually easier to understand: rather than relying on an ability to forecast the future, crickets appear instead to respond mainly to the resources they have in hand,” he said.

Male crickets signal to females using an energetically expensive call, produced by rubbing together their hardened forewings.

The more time they spend calling, the more mates they attract.

The paper, published in Functional Ecology, studied decorated crickets, which mate about once a day on average during their month-long adult life.

Males need a three-hour recovery period following each mating to build a new sperm package, after which they are able to call again in the hopes of attracting another female.

Researchers found that a male cricket’s decision about whether to call was primarily based on whether females were nearby – rather than how well-fed they were – but the better-nourished males were able to call for longer and thus increase their mating prospects.

The study also provides insights into how energy budgets keep male displays honest for choosy females over the course of the mating season.

“In nature, a ‘better quality’ male will likely have better access to resources,” said lead author Dr Tom Houslay, a Postdoctoral Research Associate at the University of Exeter.

“Low-quality males might be able to ‘cheat’ by calling a lot one day, making females think they are high-quality, but this is not sustainable – so there is ‘honesty on average’.

“A female may be fooled once or twice, but over time males with more energy will call more – meaning females should tend to make the ‘correct’ decision by preferring those males.”

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Scottish Ecological Ageing Research Meeting

The magnificent peacock advances into later years…

As a brief digression here from what is likely to be a long drawn-out series of Evolution 2012 posts, I thought I’d briefly mention a meeting which I went to earlier this week. The Scottish Ecological Ageing Research group has an annual meeting which generally covers a variety of topics within the broad remit of ‘ageing’; this year, the definition of the group was pushed even further by the host institution being Durham University. For those of you who are not up on UK geography, Durham is in England. A great selection of talks was put together by organiser David Weinkove, from Lyndsey Stewart‘s investigation of the compound resveratrol’s effect on later-life cognitive performance to Nick Priest‘s mathematical modelling approaches to finding ‘hidden heterogeneity’ in demographic data (by way of systems modelling of the nutrient sensing network, and the impact of migration on reproductive ageing among the UK’s Bangladeshi population!). 

We were also treated to a talk by Dan Nussey of the University of Edinburgh’s Wild Evolution group, talking about the amazing long-term work they’ve been doing on the Soay sheep on St Kilda. I still live in hope of being able to go over and join in their annual round-ups of the sheep for data collection, although when I asked Dan about it at last year’s meeting I caught the eye of my supervisor, who simply hissed “you’ve got work to do” at me from across the table…! Anyway, while I’m on the subject, it’s definitely worth taking a look at the Wild Animal Modelling Wiki site if you’re at all interested in how quantitative genetic methods can be used on data taken from natural populations (although still useful for those of us looking at lab populations as well). Also, stay tuned for the rest of my Evolution 2012 Ottawa posts, where I’ll discuss the amazing work in this vein presented by Jane Reid of Aberdeen University, and by Alistair Wilson of Edinburgh.

Having followed my crickets for their entire lifetimes on a huge experiment I performed at the outset of my PhD, I also presented some work that sort of fits the ageing bill. I delivered the same talk I’d given at Evolution Ottawa last week – with a couple of alterations made after being a little unhappy with my performance there – although this was slightly less nerve-racking (mostly because I was now in a normal-sized room, and my slides weren’t projected onto a cinema-sized screen!). It seemed to go down quite well, or at least I’m going to take the fact that I had to contend with around 10 minutes worth of questions to suggest this was the case…

Although Ottawa was an incredible experience, I really value these smaller one-day meetings (having attended a maternal effects meeting at the University of Edinburgh this year, and presented at the Scottish Animal Behaviour meeting). They bring together a very diverse group of individuals and research interests under a loose umbrella, and it’s great to get feedback and thoughts from other people, as well as to see what else is going on. From a purely selfish point of view, it’s also great experience to present in a slightly less terrifying situation than the one I found myself in last week!