I aligned a read against NCBI-nr using Diamond and obtained matches against 3 accessions of the same organism: Lupinus albus (taxID = 3870). Then, I used daa-meganizer (MEGAN 6_19_1) using the database megan-map-May2020.db.
I observe differences between the taxID in my blast output and the assignment made by Megan: my three accessions of the same species (taxID = 3870) were assigned to taxID 0, 131567 and 3870 by Megan. Why such differences? As my blast output contain the taxID information, is there a way to extract them with daa-meganizer instead of using a database?
The following table present the differences observed between blast and megan result:
Accession Blastx_taxID Megan_taxID
KAF1858427.1 3870 0
KAF1858500.1 3870 131567
KAF1858388.1 3870 3870