Loss of a gluconeogenic muscle enzyme contributed to adaptive metabolic traits in hummingbirds

Science. 2023 Jan 13;379(6628):185-190. doi: 10.1126/science.abn7050. Epub 2023 Jan 12.

Abstract

Hummingbirds possess distinct metabolic adaptations to fuel their energy-demanding hovering flight, but the underlying genomic changes are largely unknown. Here, we generated a chromosome-level genome assembly of the long-tailed hermit and screened for genes that have been specifically inactivated in the ancestral hummingbird lineage. We discovered that FBP2 (fructose-bisphosphatase 2), which encodes a gluconeogenic muscle enzyme, was lost during a time period when hovering flight evolved. We show that FBP2 knockdown in an avian muscle cell line up-regulates glycolysis and enhances mitochondrial respiration, coincident with an increased mitochondria number. Furthermore, genes involved in mitochondrial respiration and organization have up-regulated expression in hummingbird flight muscle. Together, these results suggest that FBP2 loss was likely a key step in the evolution of metabolic muscle adaptations required for true hovering flight.

MeSH terms

  • Animals
  • Birds / genetics
  • Energy Metabolism
  • Flight, Animal* / physiology
  • Gluconeogenesis* / genetics
  • Muscles