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The African coelacanth genome provides insights into tetrapod evolution
Chris T Amemiya1, Jessica Alföldi, Alison P Lee
1Molecular Genetics Program, Benaroya Research Institute, Seattle, Washington 98101, USA. camemiya@benaroyaresearch.org
Nature
|April 20, 2013
Summary
The African coelacanth genome reveals lungfish, not coelacanths, are tetrapods' closest relatives. This ancient fish genome offers insights into vertebrate evolution and the transition from water to land.
Area of Science:
- Genomics
- Evolutionary Biology
- Paleontology
Background:
- The coelacanth, a lobe-finned fish, was rediscovered in 1938, having been presumed extinct for 70 million years.
- Its ancient lineage and physical similarity to fossil relatives offer insights into early vertebrate evolution and the transition to land.
- Understanding the coelacanth's genome is crucial for tracing tetrapod ancestry.
Purpose of the Study:
- To sequence and analyze the genome of the African coelacanth (Latimeria chalumnae).
- To determine the closest living relatives of tetrapods (four-limbed vertebrates).
- To investigate genomic changes associated with the vertebrate adaptation to terrestrial life.
Main Methods:
- Whole-genome sequencing of Latimeria chalumnae.
- Phylogenomic analysis to reconstruct evolutionary relationships.
- Comparative genomics to identify changes in genes and regulatory elements.
- Functional assays of regulatory elements (enhancers).
Main Results:
- Phylogenomic analysis identified lungfish as the closest living relatives of tetrapods, not coelacanths.
- Coelacanth protein-coding genes evolve significantly slower than those of tetrapods.
- Identified key genes and regulatory elements involved in vertebrate adaptation to land, including immunity, nitrogen excretion, and sensory/limb development.
- Functional assays confirmed the role of coelacanth enhancers in the fin-to-limb transition.
Conclusions:
- Lungfish, not coelacanths, are the closest living relatives of tetrapods.
- The coelacanth genome provides a valuable resource for understanding the genetic basis of vertebrate evolution, particularly the transition to land.
- Evolutionary rates of protein-coding genes differ between coelacanths and tetrapods, offering insights into distinct evolutionary pressures.
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