Manipulate[
p1=P1;
p2=1-p1;
(*λ1 = 1.2;*)
λ2 = 2*λ1;
Plot[{Log[p1*λ1+p2*λ2],p1*Log[λ1]+p2*Log[λ2]},{λ1,1,2},Frame->True,FrameLabel->{"(Subscript[λ, 1]) (patch/season 1 per-capita growth rate)","r (overall growth rate)"}, PlotLegends->{"Spatial","Temporal"},PlotRange->{0,1.5}],
{P1,0,1}]