Guppy Love is a Two-Sided Story

Jun 20, 05:29 AM

Current Headlines: By Fergus Sheppard

WHEN playing the game of love, it is a given that any amorous male is going to show off his best side to get the girl.

But new research suggests that even the humble guppy fish puts its best fin forward when it comes to winning a mate.

A study published yesterday by researchers at the University of Toronto has revealed that the male guppy - Poecilia reticulata - is able to recognise its best side and display it to female fish.

While animals, birds and fish are known to have courtship rituals - often quite involved ones - the finding is significant as it suggests even fish have the ability to manipulate what was previously thought to be instinctive behaviour.

For example, male peacocks display their plumage, but have not - until now - been thought to tailor that display to show some feathers more than others.

Scientists at the university's department of ecology and evolutionary biology carried out their tests on 53 male guppies, each of which was exposed to a number of females.

Colour is highly significant in guppy courtship - males are often bright orange in colour, while females are bland in appearance. In males, that pigmentation may not be evenly displayed across the body, however, with one side more distinctive than the other.

Female guppies are thought to believe the future is bright when a prospective partner is orange. Strong colouring sends a positive message about the male's overall genetic fitness to be a mate. Size also matters to female guppies: they are known to prefer bigger partners.

The three Canadian scientists who carried out the research found that when male and female guppies were placed side by side in tanks, those males with uneven markings would make a clear effort to show off their best orange side.

Their report concludes: "We suggest that displaying or using one's best side may be an overlooked but widespread behavioural pattern in nature."

However, just as in the human world, the female of the species may be wise to swaggering displays of male piscine preening and it is uncertain whether attempting a sleight-of-fin buys the inadequate male any long-term advantage.

The research states: "Female guppies may have evolved a resistance to dishonest signalling by males, perhaps by paying increased [attention] to detect deception by assessing the total amount of orange on both sides of the male, regardless of its display behaviour."

A top Scottish expert on behaviour last night described the study as "striking".

Psychologist Dr Ben Jones, who heads Aberdeen University's face research laboratory, said: "Males are known to have signals that are attractive [to females of a species]. What this new study shows is that males are deliberately manipulating what aspects of these signals are visible to the female - literally putting their best face forward.

"It is extremely likely this is something that will crop up in human courtship; you would be astounded if it didn't."

SIZE - AND COLOUR - MATTER IN SEXUAL ATTRACTION

THE Toronto University study is not the first time guppies have been used to examine sexual selection. Two previous major scientific studies have looked at the interplay between the males - which are highly colourful and court multiple females - and females, which are comparatively bland in appearance and give birth to live young.

Those studies - carried out in 1997 and 2005 - established that female preference in guppies is linked to attractive, ornamental colouring - both carotenoid (orange) and melanin pigmentation. Female guppies also displayed a preference for larger mates aside from the issue of colouring.

A 1999 study by researchers at the University of Melbourne suggested that the "best" side people put forward may be connected to the kind of emotion they want to display, consciously or unconsciously. In an experiment, sitters asked to show as much emotion as possible often displayed the left side of their face, which is governed by the emotive right cerebral hemisphere of the brain.

By contrast, when subjects were asked to pose as scientists and not display emotion, they showed their right side.

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