Practically Dinosaurs: Crocodiles Mutate Really Slowly

Researchers have determined that crocodilians mutate at a remarkably slow rate, providing a potential explanation for why these creatures are so much more like their prehistoric ancestors compared to most other creatures.

"Research shows that compared to bird genomes, crocodilians evolved approximately four times more slowly than birds," scientist Jaime Gongora, at Sydney University, said in a recent release. "It challenges us to solve the mystery of how the crocodilians have maintained their genetic diversity and survived for hundreds of millions of years - given this slow mutation rate."

Gongora and her colleagues compared the cocodillian genome to related groups, like turtles and birds, and determined some of the characteristics shared between these lineages.

The resulting findings were published in the journal Science and include data that is expanded upon in a pair of companion papers in the journals Retrovirology and PLOS One.

According to these studies, while the other animal groups experience relatively frequently mutations to help facilitate the natural selection of beneficial traits, crocs experienced very little change. And while that could be explained with the fact that, despite mutations, they simply didn't needs to change or adapt much (as seen with many aquatic worms and crustaceans), the authors of these studies suggest that it has a lot more to do with a slow mutation rate.

"We can use these genome resources to investigate the diversity of captive and wild saltwater crocodile populations to better understand their disease resistance, and their susceptibility and specific adaptations to their environments", Gongora explained.

The work also has implications for crocodile farming,  a growing industry that centers around crocodlie size and skin quality- factors which can be ruined by the spread of illness.

"Crocodile farming is a conservation success story but understanding the underlying genomic differences will enhance our ability to farm crocodiles ethically, efficiently and effectively," added Sally Isberg from the Centre for Crocodile Research.

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