Loading Ape Package and reading in butterfly file

#install.packages("ape")
library(ape)


butterfly <- read.table("butterfly.seq", sep = ",", header = F)

Downloading required sequences from Genbank, to be stored as a single variable

sequences <- read.GenBank(butterfly$V1,
                          seq.names = butterfly$V1,
                          species.names = TRUE,
                          as.character = TRUE)

Exporting the butterfly sequence as a FASTA file

write.dna(sequences, "butterfly.fasta", format = "fasta")