because:
The birds
among them:
chicken and zebra finch （long insert sanger）were significantly larger than those in other birds（short insert NGS），
So I think of identity gene sequencing methods influence, but do not know the impact so big, so, overall examine the relationship between all species and their depth of:
a scatter plot between the number of identified OR genes and sequencing depth
Not found a positive correlation, so that it has little effect on the sequencing of identity gene number.