They found that adipose fins originated multiple times, independently, in catfish and other groups of ray-finned fishesa striking example of convergent evolution over a vast range of species.
"It's pretty incredible that a structure which is incredibly common could be so misunderstood," Stewart said. "Our finding, that adipose fins have evolved repeatedly, shows that this structure, long assumed to be more-or-less useless, might be very important to some fishes. It's exciting because it opens up new questions."
More than 600 species of fish were studied in the course of this research, including many from the collections of the Field Museum in Chicago. This analysis revealed that a number of complex skeletal structures, including spines, plates, fin rays and cartilage discs, evolved independently in the adipose fins of different species. And while studies of the fossil record have suggested that new fins originate in a predictable and repeated manner, adipose fins demonstrate multiple routes to building new appendages.
"These results challenge what was generally thought for how new fins and limbs evolve, and shed new light on ways to explore the full range of vertebrate limb and fin diversity," Stewart notes.
|Contact: Kevin Jiang|
University of Chicago Medical Center