[https://morgannprice.github.io/fasttree/ FastTree] infers approximately-maximum-likelihood phylogenetic trees from alignments of nucleotide or protein sequences. FastTree can handle alignments with up to a million sequences in a reasonable amount of time and memory. = Environment modules = We offer software modules for single precision and double precision calculations. Single precision is faster while double precision is more precise. Double precision is recommended when using a highly biased transition matrix, or if you want to resolve very short branches accurately. To see the available FastTree modules: module spider fasttree To load a single precision module: module load fasttree/2.1.11 To load a double precision module: module load fasttree-double/2.1.11 = Troubleshooting = * Error message ''WARNING! This alignment consists of closely-related and very long sequences'': This likely results in very short and sometimes negative branch lengths. Use a fasttree-double module for double precision. = References = * https://morgannprice.github.io/fasttree/ FastTree Web page]