For certain fishes, evolution is easy. After tracking the evolution of teeth in cichlid fishes from Africa, a team of researchers has found that these fishes have developed the ability to evolve rapidly, allowing them to adapt their teeth readily for different habitats and diets. This ability, the researchers report today in a study in Nature, helps these fishes split off into new species faster than any other fishes and, for that matter, any other vertebrates.
“This changes the way we think about key innovations,” said Nick Peoples, a study author and a graduate student at the University of California, Davis Department of Evolution and Ecology, according to a press release.
Indeed, the findings indicate that the ease of evolutionary innovation is as important in driving speciation as an evolutionary innovation is itself, speeding the development of new species in easily evolving lineages.
Read More: Does Evolution Take Millions of Years or Does it Happen in Sudden Bursts?
Teeth Transitions
Among the fishes, there are a few options for teeth: Some fish sport “simple” conical teeth, while others sport “complex” cusped teeth. These differences allow them to survive in distinct habitats and on distinct diets. But African cichlids are famous for making the most of these two types of chompers, taking on more distinct habitats and more distinct diets than most other fish species.
A surprisingly large lineage, African cichlids are adaptable, some studded with cones and some studded with cusps that allow them to pierce and tear through algae, plants, and prey, and it is these variations in teeth that are thought to fuel their adaptability.
Setting out to explore the evolution of these toothy variations, Peoples studied the teeth of 30,000 fish species, including 1,000 African cichlid species, for two years. Tracing their evolutionary history, he tracked their transitions from simple to complex teeth.
He found that teeth evolved from simple to complex around 86 times across all fish species and that these transitions were common in African cichlids, which adapted with a certain ease of evolution. In fact, in addition to switching from simple to complex, the teeth of these fishes also transitioned from complex to simple, all at an impressive evolutionary pace.
Read More: How Does Speciation Drive Evolution?
Evolutionary Ease
Peoples and his team thus concluded that African cichlids’ ability to easily evolve their teeth, from simple to complex and back, was an evolutionary advantage all on its own, allowing the fish to adapt to different habitats and diets.
“It’s not just the teeth, it’s how quickly they are gained or lost,” Peoples said in the release. Retaining the genetic requirements for cones and cusps alike, these fish are able to transition between the two teeth types much more rapidly.
According to the researchers, this ease of evolution allows African cichlids to churn out new species much more readily than any other vertebrates. Indeed, African cichlids are famous for their rapid speciation, as scientists have described some 1,700 species and are continuing to discover more. (Of these, many are found only in a single lake, like Lake Victoria or Lake Malawi, which both support over 500 species of cichlids).
The researchers say that their finding that evolutionary ease is itself an innovation that fosters speciation is not limited to African cichlids. It isn’t even limited to fish. There are plenty of other lineages that are famous for their diversity, and further investigation may find that evolution, at least for a specific trait like teeth, is easy for those lineages, too.
Read More: How Do We Define A Species?
Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
Nature. Evolutionary Lability of a Key Innovation Spurs Rapid Diversification
EvoDevo. East African Cichlid Fishes
Sam Walters is a journalist covering archaeology, paleontology, ecology, and evolution for Discover, along with an assortment of other topics. Before joining the Discover team as an assistant editor in 2022, Sam studied journalism at Northwestern University in Evanston, Illinois.
