An Adélie penguin breeding colony, Edmonson Point, Antarctica. Adélie penguin nests consist of a shallow scrape, pebbles, and bones. Credit: Carlo Baroni and Maria Cristina Salvatore, University of Pisa
Key points:
- Researchers sequenced and compared the genomes of ancient and modern Adélie penguins to study the evolution of microsatellites.
- Over thousands and even millions of years, microsatellites persist through speciation events and their length remains extremely stable.
- The sequencing of ancient and modern Adélie genomes is an incredible resource for future research that sets the stage for investigation into more complex models of microsatellite evolution.
Microsatellites are useful tools for studying inheritance, genetic diversity, and population dynamics across a wide range of organisms. A new study, published in Genome Biology and Evolution, reveals new insights into the evolution of microsatellites through the analysis of Adélie penguin genomes.
Researchers sequenced the genomes of 23 ancient Adélie penguin specimens dating back over 46,000 years in addition to samples from 26 modern Adélie penguins. With these samples, they can directly compare ancient and modern individuals, which is relatively uncommon in evolutionary studies. The team also compared the dataset with over 27 million microsatellite loci from 63 other animal genomes to examine microsatellite dynamics over more than 500 million years.
Their analysis revealed some unexpected results. One of the most surprising findings was that microsatellite length remained extremely stable over thousands and even millions of years. Researchers determined that microsatellites tend to grow by an average of one nucleotide every 100 million years, suggesting a dynamic equilibrium in the replication slippage process.
Longer microsatellites tend to get shorter and shorter microsatellites tend to get longer to maintain microsatellite length over time.
Researchers were also surprised to find that microsatellites were long lived. They identified some loci that persisted for over half a billion years and many speciation events.
“Microsatellites might play a functional role in the architecture of the genome or in generating phenotypic diversity,” said the authors. “It seems unlikely that they would persist so long unless they were being protected from degeneration by purifying selection.”
The sequencing of ancient and modern Adélie genomes is an incredible resource for future research. They set the stage for investigation into more complex models of microsatellite evolution that include both point mutations and slippage. Additionally, the data will support the study of the evolution of other types of genetic elements and repetitive DNA sequences.