Ocean life
Ancient jellyfish show repeated genetic evolution
A genetic study of distant jellyfish lineages shows that identical molecular changes happen far more frequently in nature than scientists previously assumed.
Reported by Phys.org · · 1 min read
Marine scientists investigating the evolutionary history of jellyfish have discovered that distantly related species frequently develop matching genetic mutations. The finding reveals that molecular convergence, where separate branches on the tree of life undergo identical genomic modifications, is significantly more common than experts previously believed.
The investigation examined Medusozoa, an ancient group of marine animals that first arose around 650 million years ago. Over hundreds of millions of years, various members of this group independently developed similar outward features, such as eyes, while multiple lineages independently stopped developing into free-swimming medusae. Biologists wanted to understand whether these shared physical developments were driven by the same underlying alterations in their DNA.
Decoupled traits
To explore this dynamic, scientists from UC Santa Barbara collaborated with colleagues at Texas A&M University, the University of Nebraska, and the University of Kansas. Together, they built an extensive evolutionary map using fossil records alongside modern molecular data. The specialists then examined all actively expressed genes across several species, checking for identical modifications appearing in separate branches separated by over 600 million years of evolutionary time.
The comparative genetic analysis uncovered an unexpectedly large count of matching genomic revisions among distinct lineages. However, these identical molecular alterations rarely matched up with the animals' shared outward forms. Instead of explaining convergent physical shapes, the molecular patterns appeared largely independent from the visible anatomical developments.
According to the study's authors, these results demonstrate that evolution at the microscopic level may be more predictable and repeatable across vast timescales than formerly recognized. At the same time, the researchers emphasized that the disconnect between shared genes and visible structures indicates that the way environmental pressures shape complex animal bodies remains far more intricate than simple one-to-one genetic formulas suggest.
