Lightweight and long-legged males go the distance for sex

Sep 05, 2008
A pair of giant weta in which the male is carrying a radio-tag on his back. Credit: Darryl T. Gwynne

Finding a mate can take considerable legwork as recently illustrated by the flightless and nocturnal Cook Strait giant weta Deinacrida rugosa. This cricket relative is found in New Zealand and is one of the world's heaviest insects with females weighing in at 20 g, averaging twice the size of males.

In a field study on Maud Island, New Zealand, published in the September issue of The American Naturalist, evolutionary biologists from the University of Toronto at Mississauga discovered that male giant weta most successful at mating travel greater distances each night. Remarkably, it appears that being lightweight and having longer legs assist male wanderlust. Clint Kelly, Luc Bussière, and Darryl Gwynne found that males can walk more than 90 m each night in search of a mate – roughly equivalent to a 7000 m outing by a human male.

Kelly and colleagues gained unprecedented insight into mating habits of weta by radio-tracking them over several days. This allowed calculations of distance walked and identification of with whom each male and female "spent the day."

Because a male giant weta copulates repeatedly with his mate throughout the day, the biologists estimated how much sperm was transferred by counting the empty packets (spermatophores) piled beneath the pair. Not only do males travel more than twice as far as females but small, long-legged individuals walked further, acquired more mates, and transferred more spermatophores to females (no female traits predicted female mobility or mating success).

"Our findings are a rare example of sexual selection favoring a suite of traits that promote greater mobility in one sex only," stated Kelly, adding " this is exciting because it suggests that sexual selection for smaller, more mobile males could be responsible for some of the impressive sexual difference in body size in this species." Importantly, however, this phenomenon may also help to explain why males are smaller than females in some other animals.

Citation: Clint D. Kelly, Luc F. Bussière, and Darryl T. Gwynne, "Sexual Selection for Male Mobility in a Giant Insect with Female-Biased Size Dimorphism." American Naturalist (2008) 172:417-423.

Source: University of Chicago

Explore further: Italian olive tree disease stumps EU

add to favorites email to friend print save as pdf

Related Stories

Venture capitalist testifies in Silicon Valley sex-bias suit

Mar 03, 2015

A prominent Silicon Valley venture capitalist who helped direct early investments in Google and Amazon said Tuesday during testimony in a high-profile sex discrimination lawsuit that his firm is not run by men and has many ...

Trial nears in high-profile Silicon Valley sex bias case

Feb 24, 2015

(AP)—A jury was picked Monday to determine whether a venerable Silicon Valley venture capital firm is liable in a sexual discrimination lawsuit or is the victim of a former employee forced out because of ...

Recommended for you

Italian olive tree disease stumps EU

20 hours ago

EU member states are divided on how to stop the spread of a disease affecting olive trees in Italy that could result in around a million being cut down, officials said Friday.

China starts relocating endangered porpoises: Xinhua

Mar 27, 2015

Chinese authorities on Friday began relocating the country's rare finless porpoise population in a bid to revive a species threatened by pollution, overfishing and heavy traffic in their Yangtze River habitat, ...

A long-standing mystery in membrane traffic solved

Mar 27, 2015

In 2013, James E. Rothman, Randy W. Schekman, and Thomas C. Südhof won the Nobel Prize in Physiology or Medicine for their discoveries of molecular machineries for vesicle trafficking, a major transport ...

User comments : 0

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.