# Pop = Replicate populations
# Gen = Generations
# NM = Male population size
# NF = Female population size
# P = Frequency of focal allele
GenDriftSim = function(Pop = Pop, Gen = Gen, NM, NF, P, graph = "y", histo = "y"){
P = (2*(NM+NF))*P
NE = round((4*NM*NF)/(NM+NF),0)
SR = round(NM/NF,2)
Na = NM+NF
if(graph=="y"){
plot(c(0,0),type = "n", main = bquote('N'[M]~'/ N'[F]~'='~.(SR)*', N'[A]~'='~.(Na)*', N'[E]~'='~.(NE)), cex.main = 1,
xlim = c(1,Gen), ylim=c(0,1), xlab = "Generations", ylab = "Fequency of focal allele")
}else{}
for (i in 1:Pop){
N = NM+NF
startA = as.vector(c(rep(1, times = P),rep(0, times = (2*N)-P)))
Population = matrix(c(
c(sample(startA, size = 2*N, replace = FALSE)),
c(rep("M", times = NM), rep("F", times = NF))),
ncol = 3)
SimResults[(Gen*i)+1-Gen, 3] <<- sum(as.numeric(Population[,1:2]))/(N*2)
for(j in 1:(Gen-1)){
Population = matrix(c(
c(sample(sample(Population[(1:NM),1:2], replace = TRUE),N, replace = TRUE)),
c(sample(sample(Population[(1+NM):N,1:2], replace = TRUE),N, replace = TRUE)),
c(rep("M", times = NM), rep("F", times = NF))), ncol = 3)
SimResults[(Gen*i)+1+j-Gen, 3] <<- sum(as.numeric(Population[,1:2]))/(N*2)
}
s = (i*Gen)-Gen+1; e = i*Gen
r = as.vector(SimResults[s:e, 3])
if(graph=="y"){
points(r~c(1:Gen), type = "l")
}else{}
}
if(histo == "y"){SimResults[,1] = rep(1:Pop, each = Gen)
SimResults[,2] = rep(1:Gen, times = Pop)
hist(SimResults[,3][SimResults[,2]==Gen], breaks = 100, cex.lab = 0.7, cex.axis = 0.7, xlim = c(0,1), cex.main = 1, main = bquote('N'[M]~'/ N'[F]~'='~.(SR)*', N'[A]~'='~.(Na)*', N'[E]~'='~.(NE)), xlab = paste0("Frequency of focal allele after ",Gen," Generations"))
}else{}
}
Pop = 10
Gen = 25
P = 0.5
SimResults = matrix(data = NA, ncol = 3, nrow = Gen*Pop)
GenDriftSim(Pop = Pop, Gen = Gen, NM = 100, NF = 900, P = P, graph = "y", histo = "n")
GenDriftSim(Pop = Pop, Gen = Gen, NM = 180, NF = 180, P = P, graph = "y", histo = "n")
dev.off()