{
  "id": 6672291,
  "title": "Physiology mediates transcontinental radiations of freshwater fishes",
  "url": "https://urgent.news/2026/09/10/physiology-mediates-transcontinental-radiations-of-freshwater-fishes",
  "topic": "science",
  "section": "Science",
  "published": "2026-09-10T00:00:00.000Z",
  "source": {
    "name": "bioRxiv",
    "slug": "biorxiv",
    "url": "https://www.biorxiv.org/content/10.64898/2026.09.04.749521v1?rss=1"
  },
  "original_language": "en",
  "account": "Adaptive radiations refer to groups of species that rapidly develop a high degree of species richness and ecological diversity. The capability to exploit new habitats, such as newly formed ecosystems, is believed to be crucial for their success. Among the most notable examples of adaptive radiations are the approximately 1,700 species of cichlids, which inhabit freshwater environments across Central and South America, Africa, India, and Madagascar. However, the factors that enabled these species to cross marine barriers and diversify in relatively young freshwater ecosystems have been a subject of debate.\n\nIn a recent study, researchers have identified a common mechanism that may provide insight into the dispersal and diversification of transcontinental freshwater fish radiations. This mechanism involves tolerance to marine salinity. It was discovered that such tolerance was retained in cichlids, killifishes, and their relatives after they emerged from a rapid radiation during the Cretaceous-Paleogene boundary, around 45 million years ago. Despite being an ancient trait, marine salinity tolerance continued to be present in these species throughout the last 45 million years of Earth's history. This endurance allowed cichlids and other fish to successfully cross marine barriers and diversify in freshwater ecosystems on multiple continents, including newly formed features in Africa and North America. These newly formed environments have repeatedly experienced saline conditions due to global climate change over tens of thousands of years. The findings of this study suggest that the broader evolutionary context of adaptive radiations can significantly influence their responses to ecological opportunities.",
  "summary": "Adaptive radiations are clades that have rapidly accumulated exceptional species richness and ecological diversity. The ability to access sources of ecological opportunity, such as new habitats, is thought to be essential for their success. Transcontinental lineages of exclusively freshwater fishes, such as the 1,700 species of cichlids distributed across Central and South America, Africa, India,…",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}