Basic genetic principles of a yet scantily explored phenomenon
Hamlets are dwellers of Caribbean coral reefs, where they exhibit a stunning diversity of colours and patterns. In a newly published article in the science journal Proceedings of the National Academy of Sciences of the USA (PNAS), the research group around population geneticist Oscar Puebla investigates the genetic mechanisms which form the basis of this exceptional diverse speciation. Puebla works at the the Leibniz Centre for Tropical Marine Research (ZMT) in Bremen. With ICBM he is affiliated by a joint professorship on fish ecology and evolution.

The diversification of animals into different species within a short period of time often is favoured by newly formed or geographically isolated habitats: primary settlers, so-called founder species, encounter unoccupied environments and lower selection pressures that favour their diversification. Complex habitats, however, without clear spatial separation, such as coral reefs, also render possible rapid diversification of species. A phenomenon which is poorly understood up to now.

The hamlets in the coral reefs of the Caribbean are represented by a remarkable number of species with an amazing variety of colours and patterns. They thus are extraordinary model organisms for investigating the basic genetic principles of this rapid diversification. Based on a genome analysis of 170 individuals from the reefs off Honduras, Belize and Panama, it could be deduced that the split into 18 species is likely to have occurred within the last 10,000 generations, even though the family tree of hamlets is about 26 million years old.

For at least some hamlet species which more recently came into existence it is thought that they are mimicking the colour patterns of other reef fish. This might be advantageous when hunting, because prey fish fail to perceive them as predators. According to Puebla, species extinction nowadays is an issue of major concern, although the formation of species as a natural evolutionary process that counteracts biodiversity loss should also be considered.

See the ZMT press release.

Publication
Hench K., Helmkampf M., McMillan W.O., Puebla O: Rapid radiation in a highly diverse marine environment (2022). Proceedings of the National Academy of Sciences of the United States of America.

Contact
Prof. Dr. Oscar Puebla
Leibniz Centre for Tropical Marine Research (ZMT)/Institute for Chemistry and Biology of the Marine Environment (university of Oldenburg)