The dependence of the Allee threshold on the parameters of the projection matrix <i>A_n</i>.

<p>To allow for a common baseline of comparison between these life history parameters, we reduced parameters one at a time such that the stable-stage population growth rate <i>λ</i> was reduced by 50% from its baseline (i.e., from <i>λ</i> = 1.056 to <i>λ</i> = 1.028). This scaling ensures that the direct effects of each parameter on the Allee threshold are separated from the effects each parameters would have on this threshold via its effects on the population growth rate <i>λ</i>. Panel (A) shows the proportional amount by which each parameter needed to be reduced relative to its baseline value to obtain <i>λ</i> = 1.028. (B) Scenarios marked orange (replotted from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0085410#pone-0085410-g002" target="_blank">Fig. 2</a>) would lead to extirpation both with the baseline parameters and the reduced parameters; scenarios marked red would lead to extirpation with the reduced parameters, but not with the baseline parameters. Each panel considers the “old” population scenario, where all females and males are sexually mature adults (i.e., in stages 4 and 10, cf. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0085410#pone-0085410-g001" target="_blank">Fig. 1</a>) at the beginning of the projection, and no female is accompanied by dependent offspring.