As any gardener knows, some plants happily grow anywhere, while others are so frustratingly fussy that even the slightest change to their ideal conditions will mean certain failure. Scale up and the same is true for plants in natural ecosystems. Some species exist over very large geographic ranges across very different climates, but others have incredibly inflexible niches that restrict their distribution. So why is this the case?
According to Dr Rachael Gallagher and Mr Tom Pyne of Macquarie University, one possible explanation is that certain species may have better abilities to adapt to local conditions than others.
“Local adaptation is an important survival mechanism for plants,” says Rachael. “Plants respond to their local environment by adapting traits such as height, leaf size, and photosynthetic capacity. As the climate changes, plants may shift their traits so they can survive. Some may do it much better than others so we’re investigating what drives this.”
“TERN’s provision of open-access, standardised ecosystem surveillance sites provided us with the opportunity to study how traits and strategies of individuals of the same species differ over climate ranges,” says Mr Tom Pyne of Macquarie University (image courtesy of Tom Pyne)
Rachael and Tom are conducting transplant experiments to measure the rates of local adaptation in certain species so we can predict how they will respond to climate change.
The team has collected the seeds of two plant species (Acacia suaveolens and Banksia serrata) from TERN ecosystem surveillance sites located at the cool and warm ends of the Biological Adaptation Transect Sydney (BATS).
Working closely with colleagues at the National Herbarium of New South Wales, who manage the BATS, they have already measured differences in germination rates and seed predation rates between populations and are now in the process of planting seedlings in their opposite environments to see how they respond.
“We’ve created two common gardens, a cold one at the Blue Mountains Botanic Garden at Mount Tomah and a warm one at Centennial Parklands in Sydney, where we can assess the performance of transplanted seedlings,” says Tom.
“We’re measuring growth and pest damage and recording important differences in characteristics to see whether plants perform better in their ‘local’ or ‘foreign’ climates.”
By collecting data on the seedlings’ key traits the team is testing the idea that there is a signal for identifying local adaptation in species.
“TERN’s provision of open-access, standardised ecosystem surveillance sites provided us with the opportunity to study how traits and strategies of individuals of the same species differ over climate ranges,” says Tom.
“If we know more about these signals of climate adaptation, we can learn a lot about how species ‘make their living’ and better predict how they will respond to climate change.”
Seeds of two plant species, Acacia suaveolens and Banksia serrata (above), have been collected from TERN ecosystem surveillance sites located at the cool and warm ends of the Biological Adaptation Transect Sydney, measured for differences in germination rates and seed predation, and will now be planted in their opposite environments to see how they respond (image courtesy of Tom Pyne)
The results of this work are also expected to have important implications for the management and revegetation of degraded landscapes, which often use seeds transplanted from external areas.
“Our research will help answer such questions as ‘is finding seed near to the revegetation site really necessary?’ and ‘will locally-sourced seeds actually provide the best form of revegetation?’,” says Rachael.
“If seed from cold-sourced individuals grows significantly better at the cold common garden and vice versa, then we may recommend that locally sourced seeds be used for revegetation. If there is no difference in survivability or growth rates, then seed can be sourced from distant locations once genetic considerations are also taken into account.”
“We look forward to seeing our results reflected in land management and revegetation programs around our study area.”
We too look forward to this and plan to keep you up to date with the outcomes of this exciting project in future editions of the TERN eNewsletter.
|Researchers use X-rays to measure insect predation on seeds (images courtesy of Tom Pyne)|
Published in TERN newsletter February 2018