Effective Population Size and Lifetime Reproductive Success
1995
ROCKWELL, R. F. | Barrowclough, George F.
The mean and variance of lifetime reproductive success, ELRS and VLRS, influence the ratio of effective to census population size, Nₑ/Nc. Because the complete data needed to calculate ELRS and VLRS are seldom available, we provide alternatives for estimating Nₑ/Nc from incomplete data. These estimates should be useful to conservation biologists trying to compute the effective size of a censused population. An analytical approach makes assumptions regarding the process influencing offspring survival. We provide a method for examining the validity of those assumptions and show that particular violations can result in either over‐ or underestimates. When the assumptions are violated or when more data are available, we suggest estimating Nₑ/Nc using computer simulations of models based on individuals. We examine how such simulations can be used to estimate Nₑ/Nc using an individual‐based model for Lesser Snow Geese (Anser caerulescens). We demonstrate that such estimates can be biased unless the simulations are based on complete cohorts and samples of known age. We show that because the estimate of Nₑ/Nc depends on the stage of the reproductive cycle used as a point of reference in the model, the census population size Nc must be based on the same stage to provide unbiased estimates of Nₑ. Tamaño poblacional efectivo y el éxito reproductivo vitalicio
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