Scientists from Murdoch University have developed a theory of evolution that explains the rapid rise of flowering plants, a phenomenon which Charles Darwin described an “abominable mystery” and one that conflicts with his notion of gradual evolution.
Murdoch researchers Associate Professor Wayne Greene, Dr Keith Oliver and Professor Jen McComb have published a scientific paper in Genome Biology & Evolution which shows that transposable elements (TEs), more commonly known as “jumping genes,” help provide the explanation for the prolific evolution of flowering plants.
Over the past four years A/Prof Greene and Dr Oliver have applied their TE-Thrust or jumping genes hypothesis to animal species but this is the first time it has been applied to plants.
A/Prof Greene said there are at least 350,000 species of flowering plants which is in sharp contrast to their non-flowering relatives which are evolving slowly and number barely 1000 species.
”Modern explanations for the success of flowering plants include their ability to undergo duplications of their entire genome as well as interspecies hybridisation and modifications for pollination by birds and insects and seed dispersal,” A/Prof Greene said.
“While these theories are valid they don’t fully explain the amazing diversification of flowering plants.
“For a more complete explanation we must consider the crucial role played in plants by jumping genes or junk DNA as it is also called.”
Jumping genes are mobile segments of DNA that can actively insert themselves or a copy of themselves, into new positions within the genome. They can arise spontaneously or can be introduced into a genome by transferring across from other species.
Once thought to be junk DNA the last two decades have shown they have been responsible for numerous traits in a wide variety of organisms.
“Jumping genes are also responsible for a range of domesticated traits such as purple cauliflower, blood oranges, white grapes, the modern shape of corn plants, spring wheat, roma tomatoes, sticky rice and wrinkled peas,” A/Prof Greene said.
TE-Thrust explains why some biological lineages have a great number of species and other have few; different rates of evolution; and the existence of seemingly unchanged species known as living fossils.
“TE thrust supports a punctuated equilibrium model of evolution, periods of rapid evolution interspersed by slower periods consistent with the fossil record,” A/Prof Greene said.
“The high percentage of mobile DNA sequences in flowering plant genomes means that they will strongly exhibit the extra evolutionary boost that TE Thrust can provide.
“Jumping genes have helped drive the origin and diversification of flowering plants by facilitating a multitude of genetic changes.”