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The above examples indicate that the exchange of genes through hybridization is an important factor in the rapid speciation of cichlids. But it is not the only reason for the African species explosion. In the journal Nature Reviews Walter Salzburger summarizes the current state of affairs. The diversity of cichlids is due to a combination of the perfect ecological possibilities in Africa and the genetic background of these fish. When the lakes were created, the cichlids were there like the chickens to fill the empty ecological niches. In addition, the genomes of cichlids have certain characteristics that enable rapid speciation. An extensive 2014 study compared the genomes of Cichlids African with those of other fish species. Below is a brief overview of the main genetic traits.
Genetic background
First, cichlids have more genetic diversity compared to other fish. This is partly due to hybridization, as the above studies indicate. Second, researchers found much duplication of genes in cichlids.
- When two or more copies of a gene are present, it is more likely that at least one of these copies will mutate and acquire a different function. Biologists call this process neo-functionalization, and it may have contributed to the rapid adaptation of cichlids to their new environment.
- Third, it turns out that gene regulation turning genes on and off is much more dynamic in the genome of cichlids compared to other fish. Certainly a plus if you have to adapt to new circumstances. Fourth, many genes show accelerated evolution.
- In this article we already gave the example of the opsin genes, but researchers found a whole list of other genes that have undergone rapid evolution. Finally, three periods were discovered during the cichlid evolution in which transposons were active. Transposons are small pieces of DNA that can copy and paste themselves into the genome.
The Right Fragments
Although these DNA fragments can cause problems for example, if they end up in the middle of a gene they also contribute to genetic diversity. The details of these processes and how they worked together to bring about the species explosion of cichlids have not yet been resolved. So there is still a lot of room for further research. So expect an explosion of papers on African cichlids in the future. But researchers found a whole laundry list of other genes that have undergone rapid evolution.
Last Words
Finally, three periods were discovered during the cichlid evolution in which transposons were active. Transposons are small pieces of DNA that can copy and paste themselves into the genome. Although these DNA fragments can cause problems for example, if they end up in the middle of a gene they also contribute to genetic diversity. The details of these processes and how they worked together to bring about the species explosion of cichlids have not yet been resolved. So there is still a lot of room for further research. So expect an explosion of papers on African cichlids in the future.
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