Tom has asked me.... what r (r1, r2) should I use? Well any r which is the same for species 1 and 2 will demonstrate my point.... but put in 0.5 if you want some number (this translates to each mature pair producing one young each year with no non-reproductive individuals in the population). If N = 1 .... yikes.... the organism is self-reproducing a Half-organism.... --- Deane