The transition from aquatic to terrestrial life has been one of the most significant evolutionary challenges. This decisive process in the evolution of life on Earth required a profound renewal of the genome. But what changes did genomes undergo to facilitate the transition to the terrestrial environment? Now, a study published in the journal Nature reconstructs the key genomic adaptations at different stages of the evolutionary transition to terrestrial ecosystems. The results show that, although each lineage followed its own evolutionary path, many adaptive functions evolved independently and repeatedly.
The study is led by Marta Álvarez-Presas, currently at the Faculty of Biology and the Biodiversity Research Institute (IRBio) of the University of Barcelona, and Jordi Paps, from the University of Bristol (United Kingdom). The first author is Jialin Wei, a PhD student under the supervision of Álvarez-Presas and Paps.
The paper outlines, for the first time, a global vision within a temporal scale of the terrestrial colonization of animals and reveals that much of the adaptation to life outside the aquatic environment is a surprisingly predictable process in response to the same environmental challenges.
How was the transition to the terrestrial environment?
Unlike plants, the study of the genomic basis of animal terrestrialization is still poorly characterized because many key groups have not been sufficiently studied at the genomic level. Recently, several initiatives have been launched to sequence these genomes, and this information is now becoming available to the scientific community for use in new studies on genes and evolution.
To try to solve some of these unknown aspects, the team analysed 154 genomes from 21 animal phyla to reconstruct the genomic adaptations associated with eleven independent events of terrestrialization. The study applies an integrative approach and combines comparative genomic analysis, functional annotation and evolutionary reconstruction of the time scale.
