DNA duplication in gymnosperms linked to their origin and evolution
Plants tend to hoard DNA, not throwing anything out. The extra genes they hold inside can mutate to produce new physical traits. Holding onto the extra genes increases the tempo of evolution for the plants. A new study has found that duplication events such as those have been vitally important throughout the evolutionary history of gymnosperms.
Gymnosperms are a diverse group of seed plants, including pines, cypresses, sequoias, ginkgos, and cycads. The research indicates that genome duplication in ancestors of modern gymnosperms likely directly contributed to the group's origin over 350 million years ago. Subsequent duplication events provided the raw material for the evolution of the innovative traits enabling those plans to persist in dramatically changing ecosystems.
Duplication events at the start of their evolution created the opportunity for their genes to evolve and create new functions, potentially helping gymnosperms transition to new habitats. In the animal kingdom, having more than two sets of chromosomes, called polyploidy, is rare, but it's very common in plants. Most fruits and vegetables we eat are polyploids, typically involving the hybridization of two closely related species.
Common plants, including wheat, peanuts, coffee, oats, and strawberries, benefit from having multiple divergent copies of DNA, leading to faster growth rates and an increase in size and weight. However, until this research, it was unclear how polyploidy may influence the evolution of gymnosperms. The recent study was a collaborative effort among plant biologists and obtained massive numbers of genetic profiles from more than 1000 plants.
The large gathering of data opened doors for scientists attempting to piece together the history of land plant evolution. The team compared the DNA of living gymnosperms and was able to look back in time to uncover evidence of multiple ancient genome duplication events coinciding with the origin of major groups. Scientists note gymnosperms have undergone significant extinctions throughout their history, making it more difficult to decipher the exact nature of their relationships.
However, all living gymnosperms shared the signature of an ancient duplication in the past more than 350 million years ago. More than 100 million years after that event, another duplication gave rise to the pine family. A third major duplication event led to the origin of podocarps, which is a group containing mostly trees and shrubs mostly restricted to the southern hemisphere. In each case, analysis revealed a tie between duplicated DNA and the evolution of unique traits.