New research suggests that the hummingbird's ability to hover is due to the loss of a gene. I wonder if the Hummingbird hawk-moth (Macroglossum stellatarum), a moth so-named for its nearly-identical hovering ability, has a similar cause for their ability.
The full paper is Loss of a gluconeogenic muscle enzyme contributed to adaptive metabolic traits in hummingbirds from which I made the abstract available here
The full paper is Loss of a gluconeogenic muscle enzyme contributed to adaptive metabolic traits in hummingbirds from which I made the abstract available here
Loss leads to gain
Hummingbirds display true hovering flight, an incredibly energy-intensive activity. Although much is known about the physiology of this movement, little has been known about the genetics underlying its evolution. Osipova et al. screened newly generated and previously sequenced bird genomes to search for key changes facilitating this high-energy locomotion. They found that a gluconeogenic muscle enzyme, FBP2, was lost as hovering flight evolved. Knockouts of this gene in avian cell lines led to an increase in glycolysis, mitochondria production, and mitochondrial respiration, all leading to higher energy efficiency. These results also illustrate how the loss of a gene can be adaptive. —SNV
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.
Hummingbirds display true hovering flight, an incredibly energy-intensive activity. Although much is known about the physiology of this movement, little has been known about the genetics underlying its evolution. Osipova et al. screened newly generated and previously sequenced bird genomes to search for key changes facilitating this high-energy locomotion. They found that a gluconeogenic muscle enzyme, FBP2, was lost as hovering flight evolved. Knockouts of this gene in avian cell lines led to an increase in glycolysis, mitochondria production, and mitochondrial respiration, all leading to higher energy efficiency. These results also illustrate how the loss of a gene can be adaptive. —SNV
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.
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