By reusing old genes, bats became the only mammals able to fly, PgI.

Key Highlights:

• Bats, the only mammals capable of true flight, evolved wings from the common five-digit limb structure found in all mammals.
• A recent study in Nature Ecology & Evolution reveals that bats reuse existing genes to develop their wings, rather than creating new ones.
• Researchers identified specialized fibroblasts in bat forelimbs that express transcription factors MEIS2 and TBX3, which are typically switched off in other mammals.
• Genetically modified mice expressing bat versions of MEIS2 and TBX3 developed webbed digits, resembling early bat wings.

Detailed Insights:

• The study challenges the earlier hypothesis that bats evolved flight by suppressing apoptosis (programmed cell death) between their digits.
• Researchers created an "interspecies limb atlas" using single-cell RNA sequencing on over 180,000 cells from embryonic limb tissue of bats and mice.
• Evolutionary co-option, the redeployment of existing gene programs, allows bats to build wings without inventing new genetic mechanisms.
• The findings may provide insights into human developmental disorders like syndactyly, where fingers remain fused.
• The research suggests that similar genetic strategies might be used in the evolution of bird wings, fish fins, and whale flippers.

Scientific/Technical Concepts Involved:

• Apoptosis: Programmed cell death, a process where cells intentionally die.
• Fibroblasts: Connective tissue cells responsible for synthesizing the extracellular matrix and collagen.
• Transcription Factors: Proteins that bind to DNA and regulate gene expression.
• RNA sequencing: A technique used to determine the RNA sequence in a biological sample.