‘Rule breaking’ plants may be the climate change survivors

Plants that break some of the ‘rules’ of ecology by adapting in unconventional ways may have a higher chance of surviving climate change, according to researchers from Trinity and the University of Queensland.

Dr Annabel Smith, from UQ’s School of Agriculture and Food Sciences, and Professor Yvonne Buckley, an honorary professor at UQ’s School of Biological Sciences and Trinity’s School of Natural Sciences, studied the humble plantain (Plantago lanceolata) in an attempt to see how it became one of the world’s most successfully distributed plant species.

Dr Smith said:

“We hoped to find out how plants adapt to hotter, drier or more variable climates and whether there were factors that made them more likely to adapt or go extinct.”

“The plantain, a small plant native to Europe, has spread wildly across the globe – we needed to know why it’s been so incredibly successful.”

The global team of more than 40 ecologists set up 53 monitoring sites in 21 countries, tagged thousands of individual plants, tracked plant deaths and new seedlings, counted flowers and seeds, and looked at DNA to see how many individual plants have historically been introduced outside Europe.

What they discovered went against existing tenets of ecological science.

Professor Yvonne Buckley marking plantain plants in one of the study areas.

“We were a bit shocked to find that some of the ‘rules of ecology’ simply didn’t apply to this species,” explained Dr Smith.

“Ecologists use different theories to understand how nature works – developed and tested over decades with field research – these are the so-called ‘rules’.

“One of these theories describes how genetic diversity or variation in genes embedded in DNA  is produced by changes in population size.

“Small populations tend to have little genetic diversity, while large populations with many offspring, such as those with lots of seeds, have more genetic diversity.

“Genetic diversity sounds boring, but actually it’s the raw material on which evolution acts; more genetic diversity means plants are better able to adapt to environmental changes, like climate change.

“We discovered that, in their native range, the environment determined their levels of genetic diversity.

“But, in new environments, these rule breakers were adapting better than most other plants.”

The team found the plantain’s success was due to multiple introductions around the world, which forced genetic diversity throughout the wider species.

“The DNA analysis showed us that ongoing introductions into Australia, New Zealand, North America, Japan and South Africa quickly prompted genetic diversity in these ‘expats’, giving them a higher capacity for adaptation,” Dr Smith said.

“In Europe plantains played by the rules, but by breaking them outside of Europe, it didn’t matter what kind of environment they were living in, the plantains almost always had high genetic diversity and high adaptability.”

Dr Smith said the finding was critical for two reasons.

“It’s important we now know that multiple introductions will mix genetic stock and make invasive plants more successful quite quickly – an important finding given invasive species cause extinction and cost governments billions of dollars,” she said.

“And secondly, research on invasive plants can give us clues about how our native plants might adapt to climate change.

“Knowing what might make our plants more adaptable, more quickly, is essential.”

Yvonne Buckley, professor of zoology, who coordinates the global Plantpopnet project from Trinity, said:

“Understanding how this little plant has managed to colonise environments as different as the sub-Arctic and sub-tropics gives us important insights into how other species might respond to climate change and introduction to new environments.”

“These kinds of critical ecological insights require highly detailed data on the life and death of thousands of individual plants and would not be possible without a high level of cooperation and collaboration between scientists throughout the world.”

The research has just been published in leading international journal PNAS.