When it comes to new botanical discoveries, one might imagine it’s done by trudging around a remote tropical rainforest. Certainly, that does still happen. But sometimes seemingly familiar plants close to home hold unexpected surprises.
We recently discovered a new genus of Australian daisies, which we’ve named Scapisenecio. And we did so on the computer screen, during what was meant to be a routine analysis to test a biocontrol agent against a noxious weed originally from South Africa.
The term “genus” refers to groups of different, though closely related, species of flora and fauna. For example, there are more than 100 species of roses under the Rosa genus, and brushtail possums are members of the Trichosurus genus.
This accidental discovery shows how much is still to be learned about the natural history of Australia. Scapisenecio is a new genus, but thousands of visitors to the Australian Alps see one of its species flowering each summer. If this species was still misunderstood, surely similar surprises are still out there waiting for us.
How it began
It all started with a biocontrol researcher asking a plant systematist, who looks at the evolutionary history of plants, to help figure out the closest Australian native relatives of the weed, Cape ivy (Delairea odorata).
Weeds like Cape ivy cause major damage to agriculture in Australia, displace native vegetation and require extensive management. Biological control (biocontrol) is one way to reduce their impact. This means taking advantage of insects or fungi that attack a weed, generally after introducing them from the weed’s home range.
A well-known Australian example is the introduction of the Cactoblastis moth in 1926 to control prickly pear in Queensland and New South Wales. Even today it continues to keep that weed in check.
To minimise the risk of selecting a biocontrol agent that will damage native flora, ornamental plants or crops, it’s tested carefully against a list of species of varying degrees of relatedness to the target weed.
Authorities will approve the release of a biocontrol agent only if scientists can show it’s highly specific to the weed. Assembling a list of species to test therefore requires us to understand the evolutionary relationships of the target weed to other plant species.
If such relationships are poorly understood, we might fail to test groups of species that are closely related to the target.
Our target weed Cape ivy is a climbing daisy that has become invasive in temperate forests and coastal woodlands throughout south-eastern Australia. One of us, Ben Gooden, is researching the potential use of Digitivalva delaireae — a stem-boring moth — for its biocontrol.
We tried to design a test list, but could not find up-to-date information on Cape ivy’s relatives. We already knew it is related to the large groundsel genus Senecio, but we didn’t know how closely. And no genetic data existed for many Australian native species of Senecio.
So, we set out to solve this problem together.
First, we assembled already-published DNA sequences for as many Senecio species and relatives as we could find, and then generated sequences for an additional 32 native Australian species.
We then united all these genetic data into a comprehensive phylogenetic analysis. “Phylogenetics” infers the evolutionary relatedness of organisms to each other.
Hidden in the evolutionary tree
The resulting “evolutionary tree” showed many of the native Senecio species where we expected them to be. More importantly, however, it showed us that Cape ivy is actually quite distantly related to Senecio.
To our surprise, the analysis also placed several Australian species traditionally belonging to the Senecio genus far outside of it, indicating they didn’t belong to Senecio at all and needed to be renamed.
The most interesting group of not-actually-Senecio are five species with leaf rosettes and one (or rarely, a few) flowerheads carried on distinctive stalks.
They’re all restricted to alpine or subalpine areas of south-eastern Australia, and all except one are found only in Tasmania. They turned out to be so unrelated, and so distinct from any other named plant genera, that they have to be recognised as a genus in its own right.
We have now named this new genus as Scapisenecio, after the long flower stalks (scapes) characterising the plants.
The most widespread and common species is Scaposenecio pectinatus, commonly known as the alpine groundsel, which is a familiar sight to hikers and bushwalkers in the Australian mainland alps and the central highlands of Tasmania.
Apart from the excitement of finding a previously undescribed, distinctive genus, these results were also directly relevant to the original purpose of our work: informing a plant list to test possible biocontrol agents.
The traditional misclassification of these species would have misled us about their true relationships. Our new genetic data now allow us to test biocontrol agents on an appropriate sample of species, to minimise risks to our native flora.
It is not often we find that a new, unexpected lineage of plants has existed all along, right in front of us.
In box gum grassy woodlands, widely spaced eucalypts tower over carpets of wildflowers, lush native grasses and groves of flowering wattles. It’s no wonder some early landscape paintings depicting Australian farm life are inspired by this ecosystem.
But box gum grassy woodlands are critically endangered. These woodlands grow on highly productive agricultural country, from southern Queensland, along inland slopes and tablelands, into Victoria.
Many are degraded or cleared for farming. As a result, less than 5% of the woodlands remain in good condition. What remains often grows on private land such as farms, and public lands such as cemeteries or travelling stock routes.
Very little is protected in public conservation reserves. And the recent drought and record breaking heat caused these woodlands to stop growing and flowering.
But after Queensland’s recent drought-breaking rain earlier this year, we surveyed private farmland and found many dried-out woodlands in the northernmost areas transformed into flower-filled, park-like landscapes.
And landholders even came across rarely seen marsupials, such as the southern spotted-tail quoll.
Huge increase in plant diversity
These surveys were part of the Australian government’s Environmental Stewardship Program, a long-term cooperative conservation model with private landholders. It started in 2007 and will run for 19 years.
We found huge increases in previously declining native wildflowers and grasses on the private farmland. Many trees assumed to be dying began resprouting, such as McKie’s stringybark (Eucalyptus mckieana), which is listed as a vulnerable species.
This newfound plant diversity is the result of seeds and tubers (underground storage organs providing energy and nutrients for regrowth) lying dormant in the soil after wildflowers bloomed in earlier seasons. The dormant seeds and tubers were ready to spring into life with the right seasonal conditions.
For example, Queensland Herbarium surveys early last year, during the drought, looked at a 20 metre by 20 metre plot and found only six native grass and wildflower species on one property. After this year’s rain, we found 59 species in the same plot, including many species of perennial grass (three species jumped to 20 species post rain), native bluebells and many species of native daisies.
On another property with only 11 recorded species, more than 60 species sprouted after the extensive rains.
In areas where grazing and farming continued as normal (the paired “control” sites), the plots had only around half the number of plant species as areas managed for conservation.
Spotting rare marsupials
Landowners also reported several unusual sightings of animals on their farms after the rains. Stewardship program surveyors later identified them as two species of rare and endangered native carnivorous marsupials: the southern spotted-tailed quoll (mainland Australia’s largest carnivorous marsupial) and the brush-tailed phascogale.
The population status of both these species in southern Queensland is unknown. The brush-tailed phascogale is elusive and rarely detected, while the southern spotted-tailed quolls are listed as endangered under federal legislation.
Until those sightings, there were no recent records of southern spotted-tailed quolls in the local area.
These unusual wildlife sightings are valuable for monitoring and evaluation. They tell us what’s thriving, declining or surviving, compared to the first surveys for the stewardship program ten years ago.
Sightings are also a promising signal for the improving condition of the property and its surrounding landscape.
Changing farm habits
More than 200 farmers signed up to the stewardship program for the conservation and management of nationally threatened ecological communities on private lands. Most have said they’re keen to continue the partnership.
The landholders are funded to manage their farms as part of the stewardship program in ways that will help the woodlands recover, and help reverse declines in biodiversity.
For example, by changing the number of livestock grazing at any one time, and shortening their grazing time, many of the grazing-sensitive wildflowers have a better chance to germinate, grow, flower and produce seeds in the right seasonal conditions.
They can also manage weeds, and not remove fallen timber or loose rocks (bushrock). Fallen timber and rocks protect grazing-sensitive plants and provide habitat for birds, reptiles and invertebrates foraging on the ground.
So can we be optimistic for the future of wildlife and wildflowers of the box gum grassy woodlands? Yes, cautiously so.
Landholders are learning more about how best to manage biodiversity on their farms, but ecological recovery can take time. In any case, we’ve discovered how resilient our flora and fauna can be in the face of severe drought when given the opportunity to grow and flourish.
Climate change is bringing more extreme weather events. Last year was the warmest on record and the nation has been gripped by severe, protracted drought. There’s only so much pressure our iconic wildlife and wildflowers can take before they cross ecological thresholds that are difficult to bounce back from.
More government programs like this, and greater understanding and collaboration between scientists and farmers, create a tremendous opportunity to keep changing that trajectory for the better.
It was my first official day of annual leave from work today and of course it had to start with a good sleep-in, which I might add I’m going to try and avoid doing for the entire period of my annual leave – just the first couple of days. I have been extremely tired, so a few sleep-ins will be helpful – for my health and well being you know. I’m sure you know what I’m talking about and agree with me entirely. I take your silence as tacit agreement. Thank you for that.
Once I was up I thought I should do something – so the day wouldn’t be viewed as an entire waste. So a drive to Bulahdelah was on the cards via the Myall Lakes National Park and the Bombah Point Ferry. So that’s what I decided to do, after I thought through a few more possible options for…
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I ran out of time yesterday to post about my walk up Yacaaba Headland and how I only just avoided being in a storm that was moving in. So today (it’s actually the 27th July 2012 as I type away) I must get two days of posts done, even if I slip this one in back in time, so to speak (as you can with the post time when posting).
So I decided to do the Yacaaba Headland walk just before lunch and had lunch in the carpark, while reading the paper. Nothing too healthy – I tend to eat far too much junk when I’m on holidays. So it was a bacon & egg roll, as well as a couple of potato scallops and some chips (and coke of course) See Picture at Left. It was really brunch and I needed the energy boost to accomplish the walk. Sounds…
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