Funding for this research was provided by:
National Natural Science Foundation of China (31272495)
Text and Data Mining valid from 2019-01-02
Received: 11 October 2018
Accepted: 18 December 2018
First Online: 2 January 2019
Compliance with ethical standards
: The authors declare that they have no competing interests.
: All the sequence data used in the study were downloaded from the nucleotide repository of National Center for Biotechnology Information (NCBI; ExternalRef removed). The other data generated in the study were included in this published article and its Additional files.