In some embodiments, techniques for identifying one or more species in an undifferentiated environmental sample comprising a plurality of nucleic acid sequences are provided. One or more indices that represent a plurality of reference nucleic acid sequences may be provided, and data may be received comprising digital representations of respective nucleic acid sequences. The respective nucleic acid sequences may be aligned, if possible, using the indices. A respective alignment ration may be calculated for each one of the reference nucleic acid sequences, based on the number of nucleic acid sequences aligned to the respective reference nucleic acid sequence and the total number of nucleic acid sequences in the received data.