Assuming different initial North American big-game-animal populations (75-150 million animals) and different population growth rates for the human settlers (0.65%-3.5%), and varying kill rates, Mosimann and Martin derived figures of between 279 and 1,157 years from initial contact to big-game extinction.

请问老师，这里的of是哪种用法？ 有没有of是不是都是一样的意思？