Off Yahoo! News
Wed Dec 10, 1:06 PM ET
LONDON (Reuters) - Trophy-hunting has
taken an evolutionary toll on Canada's bighorn sheep, scientists said on
Wednesday.
Their magnificent horns are getting
smaller because the biggest rams with the most impressive examples are being
shot before they have mated and passed on their genes.
"Because you don't have the best rams
mating, they aren't reproducing and the population isn't seeing the best
genetic variability," said Dr Curtis Strobek, of the University of Alberta
in Canada.
Strobek and his colleagues studied
30 years of data on bighorn sheep from a population at Ram Mountain in Alberta.
Bighorn sheep in Canada, which can weight up to 340 kg (750 lb) are found
mainly in western Alberta and southern British Columbia.
The researchers used quantitative genetic
analysis to determine the impact of the loss of 57 rams that were shot since
1975. Rams battle in head-to-head fights for access to females. They do their
best mating from six years and older but nine of the rams were as young as
four and most had not reached eight years old when they were shot.
"Unrestricted harvesting of trophy
rams has contributed to a decline in the very traits that determine trophy
quality," the researchers said in a report in the science journal Nature.
Although revenue from hunting is used
to conserve populations of bighorn sheep, Strobek and his team said so far
little attention has been paid to the potential evolutionary consequences
of hunting.
They also warned that there could be
a similar evolutionary impact on elephants in Africa where tuskless males
are becoming more common.