Comparison of transcriptional responses to extreme hypoxia between the lab population of NP and TP locusts. (A) Numbers of differentially expressed genes (DEGs) in NP and TP locusts exposed to extreme hypoxia. (B) Gene ontology (GO) classification of DEGs. The fourteen radii represent fourteen GO categories while the red and blue lines indicate the number of DEGs in each category. 1, GO:0044238 primary metabolic process; 2, GO:0051234 establishment of localization; 3, GO:0006810 transport; 4, GO:0050789 regulation of biological process; 5, GO:0007017 microtubule-based process; 6, GO:0008219 cell death; 7, GO:0005622 intracellular; 8, GO:0043226 organelle; 9, GO:0016020 membrane; 10, GO:0016491 oxidoreductase activity; 11, GO:0003676 nucleic acid binding; 12, GO:0042302 structural constituent of cuticle; 13, GO:0003700 transcription factor activity; 14, GO:0004601 peroxidase activity. (C) Cluster analysis of DEGs involved in glycolysis and energy production processes. Hierarchical clusters were calculated using Euclidean distance similarity metric and average linkage method. (D) Diagram of functional relationship of clustered genes. The upper part of the diagram represents several anaerobic metabolic processes, mainly glycolysis; the lower part represents several aerobic metabolic processes which occur mainly in mitochondria.