Understanding how biodiversity is generated is a major goal for evolutionary biologists. Instances of repeated phenotypic change – termed convergent evolution – represent an ideal framework to test which genetic factors contribute to the generation of phenotypic diversity. This is necessary not only to understand how evolution works, but also to predict how fast populations can adapt to environmental change. In this project, the evolution of the cave phenotype in Proteus anguinus, the olm, was investigated.
The olm is probably the most famous cave animal on earth, the first one to be scientifically described and prominently featured in Darwin’s ‘Origin of Species’ on the ‘use’ and ‘disuse’ of characters. It spends its life underground, protected from human sight, but unfortunately not from human actions. Water pollution and habitat degradation threaten its subterranean homeland. To investigate the evolutionary history of olms, we used novel and innovative approaches to find and sample them. Metaphorically speaking, the project aims at answering Darwin’s puzzling case of the evolution of cave creatures 150 years after his ‘Origin of Species’.
The completed objectives of the project are the reconstruction of the evolutionary history of olms, the sequencing of the olm's genome, the largest assembled tetrapod genome thus far, and the identification of crucial genes and selective processes during the evolution of the subterranean lifestyle in olms and in other vertebrates. This project represents an important step towards understanding how diversity is repeatedly generated and what drives this. The cave phenotype encompasses several traits with biomedical importance, including resistance to starvation and obesity, longevity, and eye diseases. Identifying the genetic pathways involved in these traits provides a comparative model for studying human health conditions. Moreover, the olm and the karstic groundwater ecosystem are at danger. Some lineages – including the unique ‘black proteus’ – have extremely small ranges and low genetic diversity. They are probably the rarest endemic European amphibians, and identifying their genetic diversity and demographic history is important if we are to conserve these animals and its habitats. The olm is considered a symbol of endangered natural heritage in Slovenia, and raising awareness about the needs and means to conserve it is an important aspect of the project.
