Study shows Valentine’s Day may not just be for humans

A drawing of a fruit fly
A drawing of a fruit fly

It seems that romance isn’t just restricted to humans this Valentines as scientists have revealed that male fruit flies have evolved to sing love songs to females.

Dr Allan Debelle and Dr Rhonda Snook from the department of Animal and Plant Sciences at the University of Sheffield investigated the sounds which are created by male fruit flies beating their wings, when attempting to seduce a female.

Impossible to hear with the human ear, but these infatuated insects beat their wings together at a rate of around 6000 beats per minute to produce a flirtatious fly love song.

To learn how this peculiar behaviour evolved, the researchers recorded the love songs of male fruit flies under different conditions and over many generations.

The characteristics that female flies find attractive can affect the evolution of male appearance and behaviours, as males with desirable qualities are more likely to mate more often, and pass these attributes onto their children.

Researchers kept and bred flies for 110 generations, and separated them into two different groups. In one group, females had plenty of males to choose from, and in the other, females only had access to one male.

Evolution is no quick process, and so the Sheffield scientists had to sit back and wait before they saw any results.

However, after eight long years of mating in captivity, the researchers found that males from the groups where females could be picky with their mate, the male flies were more powerful, and had greater endurance when singing their love songs.

The scientists also recorded the difference in tempo between the monogamous and promiscuous males.

Amazingly, the difference recorded between the songs of the two kinds of males is more than three times the difference in tempo between reggae and house music. Males that had to compete for the females affections had to work harder, resulting in a faster love song.

After many years of waiting, these new results suggest that choosiness when picking a mate could be very important in the evolution of mating performance, such as muscle power and endurance in romantic displays, much like the fly love song.

The ability of males of perform their songs improved slowly over time, gradually becoming more energetically demanding and longer in length, but only when the males had to compete for their females attention.

The researchers findings suggested that when females were forced to be monogamous, the males evolved to invest less energy in building larger wing muscles and did not put as much effort into their music.

Love songs and dancing are not uncommon in the animal kingdom, and are seen in many insect and bird species.