Uncovering the social life of plants
Individuals living in colonies, working together through the division of labour and cooperating to care for young is nothing new in the animal kingdom, but the discovery of this behaviour in a plant offers a major breakthrough in our understanding of how life has evolved on Earth.
Staghorn ferns can be bought at any local garden store, and will grow like any other pot plant. But in the wild on Lord Howe Island, off Australia’s East coast, a team led by Professor Kevin Burns from Te Herenga Waka—Victoria University of Wellington’s School of Biological Sciences has found colonies of the fern that display behaviours more often found in ant or bee colonies.
“This phenomenon is called eusociality, and is the most recent major evolutionary transition towards more complex lifeforms. But it’s only ever been observed in animals, and has only evolved on a handful of occasions,” says Professor Burns. “To see this in plants is really exciting and will require a significant reappraisal of plants and the evolution of life, in general.”
Biological complexity arises from abrupt ‘transitions’ not slow and continuous changes, with major evolutionary transitions occurring when independent entities begin to cooperate. There are eight, commonly recognised major evolutionary transitions in the natural world, with eusociality the most recent.
Eusocial animals differ from others in three fundamental ways: they live in colonies comprised of different generations of adults; subdivide labour into reproductive and non-reproductive groups; and care for offspring cooperatively.
“Our observations over the past two years on Lord Howe Island have found that staghorn ferns meet all these criteria,” says Professor Burns.
“These plant colonies usually grow on the branches of rainforest trees, with individual plants collaborating to build a communal store of water and nutrients to help ensure their survival.”
In order to confirm the extent of staghorn ferns’ social lives and life history, Professor Burns has applied for a Marsden Fund grant that will allow the team to conduct comprehensive testing.
“Our research project provides a turning point in our understanding of biological complexity, as it would demonstrate that plants and animals can take the same evolutionary path towards becoming more biologically complex organisms.”