Trophy Hunting Depletes Genes for Big Horn Sheep

生物谷

   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.

    From:Reuters