Geo News

A Stitch in Time

The highly endangered hihi has an appetite for sex to rival rabbits, but promiscuity and infidelity may just save the species. Even while paired up, the female hihi, or stitchbird, will be mating with another male, and her partner may be copulating with another female. Consequently, about 60 per cent of a male hihi’s nestlings will not be his own progeny. Zoological Society of London research fellow John Ewen has been studying the birds for 17 years and believes that there may be an advantage in this behaviour. With only a few thousand birds in existence, some hihi suffer from ‘inbreeding depression’—a situation common in small populations that often results in weaker offspring. Patricia Brekke, who studied this issue for her PhD, says that with extensive polygamy, the resulting population becomes far more genetically diverse because many more individuals can successfully breed and pass on their genes, and the most compatible sperm and egg matches are able to take place.

Magazine

ISSUE 109

May - June 2011

Colour morphs

Ngawi

Mt Walter

Earthquake

Lichens

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Living World

Colour Morphs

If you think these colourful oddities might be more at home in a pet shop, you’d be right. People find such rarities desirable and attractive, and so we perpetuate colour abnormalities by selectively breeding for them in captivity—everything from goldfish and blue budgies (wild budgies are green) to white mice and Irish red setters. In the wild, however, natural colour abnormalities are a rare phenomenon, seldom surviving long enough to breed and pass on their genes. Unable to be fully expressed, these genetic colour abnormalities lie latent inside normal-coloured hosts until the environment changes and a new opportunity presents itself. Only then might a new colour offer advantages in the struggle to survive.

Geography

The Beach

Like mechanical crayfish making landfall, the bulldozers that line the shore at Ngawi are an original solution for a unusual location. But as Mark Scott discovers, it’s not the only thing that makes this seaside community unique

Geography

On the edge

The face of mountain climbing in New Zealand is changing. As glaciers retreat, access to our high peaks becomes more difficult and, in some cases, near impossible. Climbers are pioneering entirely new routes to reach summits. This summer, a small team of climbers forged their way into the heart of the Spencer Glacier, and struck a new line up the sheer rock flank of Mt Walter—the first new route there in over 30 years.

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