Reconstructing the phylogeny and evolutionary history of freshwater fishes (Nemacheilidae) across Eurasia since early Eocene

Eurasia has undergone substantial tectonic, geological, and climatic
changes throughout the Cenozoic, primarily associated with tectonic plate
collisions and a global cooling trend. The evolution of present-day
biodiversity unfolded in this dynamic environment, characterised by
intricate interactions of abiotic factors. However, comprehensive,
large-scale reconstructions illustrating the extent of these influences
are lacking. We reconstructed the evolutionary history of the freshwater
fish family Nemacheilidae across Eurasia and spanning most of the Cenozoic
on the base of 471 specimens representing 279 species and 37 genera.
Molecular phylogeny using 6 genes uncovered six major clades within the
family, along with numerous unresolved taxonomic issues. Dating of
cladogenetic events and ancestral range estimation traced the origin of
Nemacheilidae to Indochina around 48 million years ago. Subsequently, one
branch of Nemacheilidae colonised eastern, central, and northern Asia, as
well as Europe, while another branch expanded into the Burmese region, the
Indian subcontinent, the Near East, and northeast Africa. These expansions
were facilitated by tectonic connections, favourable climatic conditions,
and orogenic processes. Conversely, aridification emerged as the primary
cause of extinction events. Our study marks the first comprehensive
reconstruction of the evolution of Eurasian freshwater biodiversity on a
continental scale and across deep geological time.