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Eyespot deficits
stymie peacocks
By Susan Milius
The tale of how the peacock got his eyespots has taken a new turn.
His shimmering train of feathers tipped
with eye-shaped spots ranks among the
most cited examples of what Darwin
called sexual selection. In this singles bar
approach to evolution, flashy plumage and
other ornaments arise not because they
enhance survival of the fittest but because
they favor reproduction of the sexiest.
Basic principles aren’t in doubt for the
peacock exemplar. Yet “everybody uses
it without knowing much about how it
works,” says Roslyn Dakin of Queen’s
University in Kingston, Canada.
She found that a train with especially
high numbers of eyespots did not seem
to improve a male’s chances of dazzling a
female into mating — but having too few
spots was definitely a hindrance.
That flies in the face of classic experi-
ments on peacock courtship, Dakin and
Robert Montgomerie, also of Queen’s,
acknowledge in an upcoming Animal
Behaviour. But they also report addi-
tional work suggesting a new explana-
tion for why peahens sometimes don’t
appear to care about eyespot number.
Having a lot of eyespots isn’t neces-
sarily important to a peacock’s mating
success, but having too few virtually
guarantees bachelorhood.
published reports, eyespot effects didn’t
show up among 102 peacocks for the top
75 percent of trains ranked by spot number. Yet the most eyespot-challenged
birds, flashing spot numbers only in the
120s and 130s, rarely had any mating
success at all. “It certainly looks like a
threshold,” Dakin says.
The threshold idea makes sense at first
glance, says Adeline Loyau, a peacock
researcher at the CNRS research station
in Moulis, France. The struggle to understand the long-familiar peacock, she adds,
“suggests that we are still far from unraveling the mechanisms of mate choice.” s
Robot cartwheels like a caterpillar
GoQBot curls itself up into a ball, then takes off spinning
By Rachel Ehrenberg
Inspired by a caterpillar that
makes like a wheel and rolls
away from predators, researchers have created a robot that
curls itself into a loop and peels
out at speeds faster than a half
meter per second.
Called GoQBot, the 10-centimeter-
long robot has a hammer-shaped head
and a silicone body embedded with metal
coils. The coils contract, musclelike, when
pulsed with current, and within 200
milliseconds the crawling bot becomes a
wheel and rolls off at impressive speeds.
“Once you get into a ball and rolling,
you get dramatic increases in speed,”
says Satyandra Gupta, director of the
GoQBot can curl itself into a wheel and roll along at high speed (right to left) like some caterpillars do to escape predators.
Maryland Robotics Center at the Uni-
versity of Maryland in College Park.
“This is an exciting development.”
Robots like GoQBot may someday aid
in search and rescue operations that
require both crawling through tight,
dangerous spaces and moving across flat
ground, says Huai-Ti Lin, who created
GoQBot as a graduate student at Tufts
University in Medford, Mass.
Described in the June Bioinspiration
and Biomimetics, GoQBot was designed
to help researchers better understand the
“ballistic rolling” that certain caterpillars
display when frightened.
“You poke the animal and you don’t
know where it’s gone,” says Lin, now at
Harvard University. “It’s wicked fast.”
FROM TOP: R. DAKIN; H.-T. LIN
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