Fast-developing fruit flies pay fitness price

Abstract

Let's face it, if you choose to make your home in a piece of rotting fruit, it might not be around for long, so the pressure is on for fruit flies – Drosophila melanogaster – to live their short lives fast. Pankaj Yadav and Vijay Sharma from the Jawaharlal Nehru Centre for Advanced Scientific Research, India, are intrigued by the trade-offs that fast-developing fruit flies, which emerge as pre-adults in just ~216h (29h faster than normal flies), make to accelerate their development. So, they investigated the impact of shortened pre-adult development on the fitness of these specially bred populations of fruit flies to find out what compromises they have made (p.580).Testing the flies' ability to survive pre-adult development, their adult lifespan, mass at emergence as adults, fecundity, size and ability to withstand starvation and desiccation, the duo found out that the flies had made significant compromises to reduce the time it took them to emerge as fully formed adults. Although the fast developers survived their period of development as well as regular flies, their adult fitness was significantly compromised: they were smaller and weighed less at emergence than regular flies, they lived shorter adult lives, they were less resistant to starvation and desiccation and the females produced fewer eggs. However, when the duo reanalysed the flies' fecundity relative to their body mass, they found that the smaller, fast-developing flies produced more eggs for their body mass than the larger, regular flies.So, the faster developing flies had traded-off their fitness against their accelerated development, and – as they run on a faster body clock than their regular cousins – Yadav and Sharma say, ‘our results can be taken to suggest that pre-adult development time and circadian clock period are correlated with various adult life history traits in D. melanogaster, implying that circadian clocks may have adaptive significance.’