Digest: The marsupial pouch as a key evolutionary innovation

The pouch has been repeatedly gained and lost throughout marsupial evolution. While its presence is linked to K-strategist traits like larger size and smaller litters, the reasoning behind its loss remains unclear. ​Casali et al. (2026) suggest that pouch evolution enabled the ecomorphological diversity among marsupials. Their findings open new research avenues to investigate the costs and benefits of a pouchless state, from life-history and ecology to its genetic and developmental regulators.