Choosy females make colourful males

May 9, 2006

Female fish prefer brightly coloured males because they are easier to see and are in better shape concludes Dutch researcher Martine Maan following her study of fish speciation in the East African Lakes. Environmental variation subsequently leads to differences in preference and eventually to speciation.

Evolutionary theory predicts that species can diverge if different females choose different characteristics in males. Yet females often pay attention to traits that reveal something about the quality of a male. As a result, females are likely to share the same preferences. In Lake Victoria cichlid fish, Martine Maan found a solution for this paradox: in different species, different traits reveal male quality.

She examined two closely related species, one with blue males and the other with red males. Females prefer males of the right colour, blue or red, and within those categories they choose the most brightly coloured males. They do so for good reasons: brightly coloured males from both species carry fewer parasites and are thus in better condition. Moreover, both species are adapted to different infection risks, which are associated with a difference in water depth and food choice. It is therefore in the females' interest to mate with their own males.

Red and blue light

Yet how did these differences evolve? The red species occurs in deeper water than the blue species and therefore experiences different light conditions. Behavioural experiments showed that both species have adapted to this: the red species is more sensitive to red light and the blue species is more sensitive to blue light. For females of the red species, red males are therefore more conspicuous than blue ones, and vice versa. Males of other colours are inconspicuous and unattractive, and therefore produce few offspring. Eventually only the bright red and bright blue fish remain, and two separate species can arise.

Due to the introduction of the Nile perch, deforestation and population growth, water transparency in Lake Victoria is declining. In turbid water, cichlid females are less choosy and males are less brightly coloured. This research therefore underlines the importance of measures to counteract the ongoing eutrophication of the lake.

Source: NWO

Explore further: Devastation in Philippine bird paradise

Related Stories

Devastation in Philippine bird paradise

October 6, 2015

Patches of tropical rainforest in the southern Philippines harbour some of the world's rarest birds, but nature lovers toting long-lens cameras now share them with people wielding chainsaws, traps and torches.

Determining America's most lethal animal

August 13, 2015

Animal attacks have been in the news a lot. Late last year, a 22-year-old student in New Jersey was killed by a black bear he had been photographing. This summer, swimmers off the coast of North Carolina have suffered a record ...

The secret to the sea sapphire's colors—and invisibility

July 15, 2015

Sapphirina, or sea sapphire, has been called "the most beautiful animal you've never seen," and it could be one of the most magical. Some of the tiny, little-known copepods appear to flash in and out of brilliantly colored ...

The secret of the world's smelliest flower

July 9, 2015

By happy coincidence and far from its native home in western Sumatra, titum arum, the world's smelliest bloom, flowered at Paignton Zoo in Devon and at the Royal Botanic Gardens in Edinburgh. It's a rare event, but not to ...

Recommended for you

Horn of Africa drying ever faster as climate warms

October 9, 2015

The Horn of Africa has become increasingly arid in sync with the global and regional warming of the last century and at a rate unprecedented in the last 2,000 years, according to new research led by a University of Arizona ...

Scientists paint quantum electronics with beams of light

October 9, 2015

A team of scientists from the University of Chicago and the Pennsylvania State University have accidentally discovered a new way of using light to draw and erase quantum-mechanical circuits in a unique class of materials ...

A mission to a metal world—The Psyche mission

October 9, 2015

In their drive to set exploration goals for the future, NASA's Discovery Program put out the call for proposals for their thirteenth Discovery mission in February 2014. After reviewing the 27 initial proposals, a panel of ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.