3.1 Sequencing analyses
Macroinvertebrates are absolutely predominant faunas in the
international rivers of northwest China, but few studies on
macroinvertebrates have been carried out in these rivers. In this study,
a total of 1,678 individuals were collected and utilized for the
generation of DNA barcodes. However, 451 specimens showed poor quality
and were excluded from further analyses. Accordingly,
a
total of 1227 sequences
(516-Ephemeroptera,
146-Plecoptera,
81-Trichoptera,
66-Hemiptera,
273-Diptera,
55-Coleoptera, 23-Odonata,
66-Annelida, 17-Mollusca), belonging to 189 species, 123 genera and 59
families, were successfully generated. The lengths of
all
COI sequences were no less than 600 bp for sequencing analysis.
Deletions, insertions and stop codons were not detected in the
sequences, suggesting that the COI PCR primers were efficient. All the
species exhibited high adenosine and thymine (AT)-rich bias (averaged
63.1%). Specifically, the A+T % in Trichoptera was up to 69.9% and
the lowest was shown in Diptera (55.6%).