When eucalypts swap genes

Published 22 August 2017

They are spread across the length and breadth of our continent, but just what makes some eucalypts more successful than others? And could the answer reside with the smallest of insects?

These are two of the questions that UNE post-doctoral fellow, evolutionary biologist Dr Jasmine Janes, is seeking to answer as she delves into the genetics of eucalypts.

Dr Janes is about to begin investigating the flow of genes between more common and rarer box-ironbark eucalypts. She’s particularly interested in the impacts of hybridisation – a phenomenon that enables plants to diversify and even create new, better adapted species. But it’s a double-edged sword.  In rare and restricted species, hybridisation can also delay speciation (the evolution of distinct species) and erode species integrity, because pollen typically moves more frequently from widespread species to those that are more restricted.

“I’m trying to understand how hybrid eucalypts come about – how long the exchange of genes has been occurring, which eucalypt species hybridise, and how this might be affected by different pollinators,” Dr Janes said. “If the hybridisation is more recent, it may be in response to environmental factors.”

Eucalypts are commonly long-lived, and rely on insects, birds and the wind for pollination. However, we know surprisingly little about these relationships and how they have evolved. “I’m interested to discover whether a species produces seed from all the pollen it receives or whether it selects out only the pollen it wants,” Dr Janes said. “If hybridisation is more recent, then it may mean the eucalypt species does not yet have reproductive barriers (like rejecting the pollen, to protect genetic integrity) in place.”

Using genome sequencing,  Dr Janes will compare the genetic characteristics of four rare eucalypts (Eucalyptus ophitica, E. magnificata, E. tetrapleura and E. panda) to those of 10 more widespread species. “What does that genetic profile mean in the real world?  How is it beneficial or not? Genetic differences could be something to do with drought or frost tolerance, or the species being better adapted to fire or more able to withstand pests. If they are very similar genetically, it suggests a lot of exchange between the species, which we can assume has an adaptive benefit. It will also be interesting to see if the pollinators are different or the same.”

Dr Janes will apply cutting-edge molecular techniques to these rare eucalypts for the first time and hopes to provide novel insights into how changing pollinator communities could shape gene flow in these trees. Ultimately, she hopes her work will inform conservation efforts to protect the rare eucalypts, which are ecologically important to a variety of animals.

Image: Dr Jasmine Janes, UNE post-doctoral fellow.