{NotebookFileName[],DateString[]}

Population growth

style[
t_
]:=
Style[t,Bold,FontFamily->"Arial",FontSize->14]

cmarker[
size_:10,
pos_:{0,0}
]:=Graphics[Circle[pos],ImageSize->size];
cmarker[]

dmarker[
size_:10,
pos_:{0,0}
]:=Graphics[Disk[pos],ImageSize->size];
dmarker[]

n4[
p_,
r_:1,
k_:10,
c_:0.1
]:=
r p(1-(p/k))-c p

Module[{ar=0.4,s=1,r=1,k=10,a0,as,amin=0,amax=12},
Manipulate[
If[c<r,
{a0,as}=a/.Solve[n4[a,r,k,c]==0];
Plot[n4[a,r,k,c],{a,amin,amax}
,Ticks->None
,AspectRatio->ar
,AxesLabel->style/@{"N","N'"}
,Epilog->{
Inset[cmarker[],{a0,0}],
Inset[dmarker[],{as,0}],
Arrow[{{amax,0},{as,0}}],
Arrow[{{amin,0},{as,0}}],
}
],
as=0;
Plot[n4[a,r,k,c],{a,amin,amax}
,Ticks->None
,AspectRatio->ar
,AxesLabel->style/@{"N","N'"}
,Epilog->{
Inset[dmarker[],{as,0}],
Arrow[{{amax,0},{as,0}}],
}
]
],
{{c,0.0,style["c/r"]},0,1.4,Appearance->"Labeled"}
]
]

Block[{ar=0.4,s=1,k=10,a0,as,amin=0,amax=12},
{a0,as}=a/.Solve[n4[a]==0];
Plot[n4[a],{a,amin,amax}
,Ticks->None
,AspectRatio->ar
,AxesLabel->style/@{"N","N'"}
,Epilog->{
Inset[cmarker[],{a0,0}],
Inset[dmarker[],{as,0}],
Arrow[{{amax,0},{as,0}}],
Arrow[{{amin,0},{as,0}}],
}
]
]