Fig. 2

Coverage and mitochondrial contig length. a Coverage is approximately proportional to input species biomass; therefore, sequence contiguity (contig length) should increase with coverage, up to the minimum level of coverage required to obtain a full-length (~15–20 kb) mitogenome assembly. Increasing sequencing depth beyond this point is not cost-effective. b An example from [28], showing the mitochondrial contigs obtained in a reference set (one specimen per morphologically identified species, normalized for roughly equal DNA concentration based on body size), with read coverage calculated for each contig based on number of reads mapped. c Assembly from the same study [28] but made from mixed bulk specimens. d The use of different assemblers (left: IDBA-UD; middle: Newbler; right: Celera) on a mixed sample of rainforest beetles [20], showing fairly incomplete assembly even for mitochondrial contigs with high coverage. e Combining these three assemblies in Geneious to increase sequence contiguity resolves a large number of these cases but is not completely effective