Biology 2483A Lecture Notes - Greater Prairie Chicken, Trophy Hunting, Allele Frequency
23 Nov 2012
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Document Summary
Trophy hunting and inadvertent evolution a case study: bighorn sheep populations have been reduced by 90% by hunting, habitat loss, and introduction of cattle. Hunting is now restricted and permits for a large trophy ram cost over ,000, but trophy hunting still has negative effects. Trophy hunting removes the largest and strongest males the ones that would sire many healthy offspring. In one population, 10% of males were removed by hunting each year, and the average size of males and their horns decreased over 30 years of study. This is also being observed in other species. African elephants are poached for ivory and the proportion of the population that have tusks is decreasing. Rock shrimp are all born male and become females when they are large enough to carry eggs. Commercial harvesting takes the largest individuals, which are females. Genes for switching sex at a smaller size became more common, resulting in more females, but smaller females lay fewer eggs.
