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Gaur's track in Cat Tien National Park

Shull A. M., Tipton A. R. 1987
Effective population size of Bison on the Wichita Mountains Wildlife Refuge
Conservation Biology 1: 35-41

POPGEN, a stochastic computer model that calculates the effective size (N e) of a stationary bison (Bison bison) population, was used to examine the effects of changes in demographic parameters on N e, and to analyze the genetic implications of different management strategies. With all other factors constant, an increase in either heritability of fertility or family-based mortality resulted in a decrease in N e / N. In populations where generation interval decreased (which should lead to a decrease in N e), reproductive rates increased and variance in lifetime production of offspring decrease N e / N increased indicating that reproductive rate andlor variance in lifetime production had a stronger influence on N e. than did generation interval. In addition, in populations where annual recruitment of breeders decreased (which should lead to a decrease in N e) and mean lifetime production increased, N e / N increased indicating that mean lifetime production had a stronger influence on N e than did annual recruitment of breeders. Our results demonstrate that effective population size can be much less than actual (8.4% to 29.6%) and that this relationship can be affected by various management practices.

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