diff --git a/.gitignore b/.gitignore
index a00a6c0..df93901 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,26 @@
-*profile*
\ No newline at end of file
+# Files generated by invoking Julia with --code-coverage
+*.jl.cov
+*.jl.*.cov
+
+# Files generated by invoking Julia with --track-allocation
+*.jl.mem
+
+# System-specific files and directories generated by the BinaryProvider and BinDeps packages
+# They contain absolute paths specific to the host computer, and so should not be committed
+deps/deps.jl
+deps/build.log
+deps/downloads/
+deps/usr/
+deps/src/
+
+# Build artifacts for creating documentation generated by the Documenter package
+docs/build/
+docs/site/
+
+# File generated by Pkg, the package manager, based on a corresponding Project.toml
+# It records a fixed state of all packages used by the project. As such, it should not be
+# committed for packages, but should be committed for applications that require a static
+# environment.
+Manifest.toml
+
+*profile*
diff --git a/src/Evolve/Evolve.jl b/src/Evolve/Evolve.jl
index fb3ba97..2afdbd3 100644
--- a/src/Evolve/Evolve.jl
+++ b/src/Evolve/Evolve.jl
@@ -4,9 +4,12 @@ using BioSequences
 using StatsBase
 using SubstitutionModels
 using TreeTools
+using FASTX
+using Dates
 
 export evolve!
 export compute_mutations!
+export write_seq2fasta
 
 include("main.jl")
 
diff --git a/src/Evolve/main.jl b/src/Evolve/main.jl
index ce7e4ca..57bd224 100644
--- a/src/Evolve/main.jl
+++ b/src/Evolve/main.jl
@@ -1,22 +1,59 @@
 """
 	evolve!(t::Tree, L::Int, μ=1.; model = JC69(1.), seqkey=:seq)
+
+	initialize a random sequence of nucleotides of length `L` at the root, then simulate evolution
+	by changing nucleotides at random according to a probability distribution specified 
+	by the chosen `model`, which takes the mutation rate μ and branch lengths of nodes as parameters.
+
+	The sequence at a node `n` can be accessed by `n.data.dat[seqkey]`, if a mutation has occured 
+	on the branch between node `n` and its ancestor is given as a boolean in `n.data.dat["evolved"]`.
 """
 function evolve!(t::Tree, L::Int, μ=1.; model = JC69(1.), seqkey=:seq)
 	t.root.data.dat[seqkey] = randseq(DNAAlphabet{4}(), L)
+	t.root.data.dat["evolved"]= false
 	for c in t.root.child
 		evolve!(c, model, μ, seqkey)
 	end
 end
 
 function evolve!(n::TreeNode, model, μ, seqkey=:seq)
+	n.data.dat["evolved"]= false
 	w = ProbabilityWeights(SubstitutionModels.P(model, μ * n.tau)[:,1], 1.)
 	n.data.dat[seqkey] = deepcopy(n.anc.data.dat[seqkey])
-	evolve!(n.data.dat[seqkey], w)
+	evolve_seq!(n, w, seqkey)
 	for c in n.child
 		evolve!(c, model, μ, seqkey)
 	end
 end
 
+function evolve_seq!(n::TreeNode, w, seqkey=:seq)
+	seq = n.data.dat[seqkey]
+	for (i,nt) in enumerate(seq)
+	 	newnt = sample(1:4, w)
+	 	if newnt  != 1
+			n.data.dat["evolved"] = true
+	 		if nt == DNA_A
+	 			if newnt == 2; seq[i] = DNA_C
+	 			elseif newnt == 3; seq[i] = DNA_G
+	 			elseif newnt == 4; seq[i] = DNA_T; end
+	 		elseif nt == DNA_C
+	 			if newnt == 2; seq[i] = DNA_G
+	 			elseif newnt == 3; seq[i] = DNA_T
+	 			elseif newnt == 4; seq[i] = DNA_A; end
+	 		elseif nt == DNA_G
+	 			if newnt == 2; seq[i] = DNA_T
+	 			elseif newnt == 3; seq[i] = DNA_A
+	 			elseif newnt == 4; seq[i] = DNA_C; end
+	 		elseif nt == DNA_T
+	 			if newnt == 2; seq[i] = DNA_A
+	 			elseif newnt == 3; seq[i] = DNA_C
+	 			elseif newnt == 4; seq[i] = DNA_G; end
+	 		end
+		end
+	end
+	return nothing
+end
+
 function evolve!(seq::NucSeq{4, DNAAlphabet{4}}, Q)
 	Qt = Q'
 	for (i, nt) in enumerate(seq)
@@ -49,3 +86,38 @@ function onehot(c::DNA)
 	end
 	return s
 end
+
+"""
+	write_seq2fasta(t::Tree, fasta_name::String, output_dir::String, seqkey=:seq; only_terminals=false, remove_0_mutations=true)
+
+	write evolved sequences to a fasta file with name `fasta_name`, `only_terminals` specifies if only terminal sequences should be 
+	written to the file and `remove_0_mutations` if only sequences with mutations on their branches should be written to the file. 
+"""
+function write_seq2fasta(t::Tree, fasta_name::String, output_dir::String, seqkey=:seq; 
+	only_terminals=false, remove_0_mutations=true, write_date=false, year_rate=4.73e-3)
+	mkpath(output_dir)
+	open(FASTA.Writer, output_dir *"/"*fasta_name* ".fasta") do w
+		if only_terminals
+			iter = POTleaves(t)
+		else
+			iter = POT(t)
+		end
+		for node in iter
+			if remove_0_mutations && !node.data.dat["evolved"]
+				continue
+			else
+				x = node.data.dat[seqkey]
+				if write_date
+					start_date = Date(2000,1,1)
+					dist = TreeTools.distance(node, t.root)/year_rate
+					date = start_date+Dates.Year(round(dist)) + Dates.Day(round((dist-round(dist))/365))
+					rec = FASTA.Record(node.label*"|"*string(date), x)
+				else
+					rec = FASTA.Record(node.label, x)
+				end
+				write(w, rec)
+			end
+		end
+	end
+
+end