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Researchers from The University of Tennessee in the United States has discovered the ability of some fern species to evolve in the opposite direction.
It is noted that this challenges the conventional wisdom of scientists that evolution is moving in an irreversible direction from simple forms to more complex ones. The researchers analyzed the fern’s reproductive strategies and learned that these plants still use two different ways of reproduction.
In particular, some species of chain fern (Blechnaceae) are monomorphic, where one leaf is responsible for both spore development and photosynthesis. Other chain fern species use a strategy called dimorphism, using two different types of leaves for reproduction and photosynthesis. The statement about irreversibility of evolution means that a fern that has developed a dimorphism strategy will no longer be able to return to monomorphism
The researchers analyzed specimens from the Natural History Collection, looking at more than 118 species and finding that fern evolution is neither sequential nor irreversible. They identified several species of chain fern that have developed dimorphism, but later returned to monomorphism.
According to scientists, the fern’s lack of seeds, flowers, or fruits allows these plants to choose between strategies dimorphism and monomorphism depending on environmental conditions. Whereas plants that reproduce through seeds can no longer revert to previous evolutionary mechanisms.
«There is no finish line in evolution. There is no final goal, no final state. Our results show that not all plant reproductive specialization is irreversible. Instead, it may depend on how many ways of evolutionary adaptation plants have acquired over time», — notes is an associate professor at the University of Tennessee, Jacob Suissa.
The research findings will help scientists better understand how to different types of plants respond to climate change and environmental changes caused by human activity. Organisms that have evolved unilaterally may lack the flexibility to respond to new selection factors in a particular way and have to find new strategies to change. Species such as ferns have evolved the ability to revert to earlier, simpler strategies even after more complex evolutionary mechanisms have developed.
The results of the study are published in the journal Evolution
Source: New Atlas