Gene Ontology and KEGG pathway enrichment analysis
The Gene Ontology (GO) function significant enrichment analysis provided a GO function term that was significantly enriched in candidate genes compared with the entire genetic background of the species. The analysis first maps all candidate genes to each term in the Gene Ontology database (http://www.geneontology.org/). Then, the software ‘GO::TermFinder’ (https://metacpan.org/ pod/GO::TermFinder) was used to calculate the number of genes in each term, and then the hypergeometric test was applied to find GO terms that were significantly enriched in candidate genes compared with the background of all genes in this species. For KEGG pathway enrichment analysis, the candidate genes were first mapped to the KEGG pathway term in the public database (Kanehisa et al., 2008). Then, a hypergeometric test was applied to find pathways that were significantly enriched in the candidate gene map to the entire genome background. After the calculated P-value was corrected by Bonferroni (Abdi, 2007), the GO terms or KEGG pathway terms of whichQ -value (corrected P -value) ≤ 0.05 were defined as significantly enriched GO/KEGG pathway terms.