Shocking Organs

The electric organs fish use to navigate and communicate -- mystifying to scientists in that they have shown up repeatedly in unrelated fish species -- evolved in their hosts because certain developmental pathways were modified in each one, a new study reports. The work of Gallant and colleagues looking at electric eels, and three other fish lineages suggests that a common genetic regulatory network was repeatedly targeted by natural selection, shaping the development of electric organs in creatures that needed them to survive

Little is known about the genetic basis of convergent traits that originate repeatedly over broad taxonomic scales. The myogenic electric organ has evolved six times in fishes to produce electric fields used in communication, navigation, predation, or defense. We have examined the genomic basis of the convergent anatomical and physiological origins of these organs by assembling the genome of the electric eel (Electrophorus electricus) and sequencing electric organ and skeletal muscle transcriptomes from three lineages that have independently evolved electric organs. Our results indicate that, despite millions of years of evolution and large differences in the morphology of electric organ cells, independent lineages have leveraged similar transcription factors and developmental and cellular pathways in the evolution of electric organs.