A detailed eucalypt family tree helps us see how they came to dominate Australia



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In Australia you can have any tree you want, as long as it’s a eucalypt.
Shutterstock

Andrew Thornhill, James Cook University

Eucalypts dominate Australia’s landscape like no other plant group in the world.

Europe’s pine forests consist of many different types of trees. North America’s forests change over the width of the continent, from redwood, to pine and oak, to deserts and grassland. Africa is a mixture of savannah, rainforest and desert. South America has rainforests that contain the most diversity of trees in one place. Antarctica has tree fossils.

But in Australia we have the eucalypts, an informal name for three plant genera: Angophora, Corymbia and Eucalyptus. They are the dominant tree in great diversity just about everywhere, except for a small region of mulga, rainforest and some deserts.

My research, published today, has sequenced the DNA of more than 700 eucalypt species to map how they came to dominate the continent. We found eucalypts have been in Australia for at least 60 million years, but a comparatively recent explosion in diversity 2 million years ago is the secret to their spread across southern Australia.

Hundreds of species

The oldest known Eucalyptus macrofossil, from Patagonia in South America, is 52 million years old. The fossil pollen record also provides evidence of eucalypts in Australia for 45 million years, with the oldest specimen coming from Bass Strait.

Despite the antiquity of the eucalypts, researchers assumed they did not begin to spread around Australia until the continent began drying up around 20 million years ago, when Australia was covered in rainforests. But once drier environmental conditions kicked in, the eucalypts seized their chance and took over, especially in southeastern Australia.

Eucalypts are classified by their various characteristics, including the number of buds.
Mary and Andrew/flickr, CC BY-NC-SA

There are over 800 described species of eucalypts. Most of them are native only to Australia, although some have managed to naturally escape further north to New Guinea, Timor and Indonesia. Many eucalypts have been introduced to other parts of the world, including California, where Aussie eucalypts make cameos in Hollywood movies.

Eucalypts can grow as tall trees, as various multi-trunk or single-trunk trees, or in rare cases as shrubs. The combination of main characteristics – such as leaf shape, fruit shape, bud number and bark type – provided botanists with enough evidence to describe 800 species and estimate how they were all related to each other, a field of science known as “taxonomy”.

Since the 1990s and early 2000s, taxonomy has been slightly superseded by a new field called “phylogenetics”. This is the study of how organisms are related to each other using DNA, which produces something akin to a family tree.

Phylogenetics still relies on the species to be named though, so there is something to sample. New scientific fields rely on the old. There have been a number of eucalypt phylogenetic studies over the years, but none have ever sampled all of the eucalypt species in one phylogeny.




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Our new paper in Australian Systematic Botany aimed to change that. We attempted to genetically sample every described eucalypt species and place them in one phylogeny to determine how they are related to each other. We sampled 711 species (86% of all eucalypts) as well as rainforest species considered most closely related to the eucalypts.

We also dated the phylogeny by time-stamping certain parts using the ages of the fossils mentioned above. This allowed us to estimate how old eucalypt groups are and when they separated from each other in the past.

Not so ancient

We found that the eucalypts are an old group that date back at least 60 million years. This aligns with previous studies and the fossil record. However, a lot of the diversification in the Eucalyptus genus has happened only in the last 2 million years.

Gum trees are iconic Australian eucalypts.
Shutterstock

Hundreds of species have appeared very recently in evolutionary history. Studies on other organisms have shown rapid diversification, but none of them compare to the eucalypts. Many species of the eucalypt forests of southeastern Australia are new in evolutionary terms (10 million years or less).

This includes many of the tall eucalypts that grow in the wet forests of southern Australia. They are not, as was previously assumed, ancient remnants from Gondwana, a supercontinent that gradually broke up between 180 million and 45 million years ago and resulted in the continents of Australia, Africa, South America and Antarctica, as well as India, New Zealand, New Guinea and New Caledonia.

The eucalypts that grow natively overseas have only made it out from Australia in the last 2 million years or less. Other groups in the eucalypts such as Angophora and Corymbia didn’t exhibit the same rapid diversification as the Eucalyptus species.




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What we confirmed with the fossil record using our phylogeny is that until very recently, and I mean in terms of the Earth being 4 billion years old, the vegetation of southeastern Australia was vastly different.

At some point in the last 2-10 million years the Eucalyptus arrived in new environmental conditions. They thrived, they most likely helped spread fire to wipe out their competition, and they then rapidly changed their physical form to give us the many species that we see today.

Very few other groups in the world have made this amount of change so quickly, and arguably dramatically. The east coast of Australia would look very different if it wasn’t dominated by gum trees.

The next time you’re in a eucalypt forest, take a look around and notice all of the different types of bark and gumnuts and leaves on the trees, and know that all of that diversity has happened quite recently, but with a deep and long link to trees that once grew in Gondwana.

They have been highly advantageous, highly adaptable and, with the exception of a small number of species, are uniquely Australian. They are, as the press would put it, “a great Australian success story”.The Conversation

Andrew Thornhill, Research botanist, James Cook University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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How indigenous expertise improves science: the curious case of shy lizards and deadly cane toads



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The Balanggarra Rangers are land management representatives of the Balanggarra people, the indigenous traditional owners of the East Kimberley. (L-R) Wes Alberts, Bob Smith (coordinator) James ‘Birdy’ Birch, Isiah Smith, Quentin Gore.
The Kimberley Land Council, Author provided

Georgia Ward-Fear, University of Sydney and Rick Shine, University of Sydney

It’s a common refrain – western ecologists should work closely with indigenous peoples, who have a unique knowledge of the ecosystems in their traditional lands.

But the rhetoric is strong on passion and weak on evidence.

Now, a project in the remote Kimberley area of northwestern Australia provides hard evidence that collaborating with Indigenous rangers can change the outcome of science from failure to success.




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Fighting a toxic invader

This research had a simple but ambitious aim: to develop new ways to save at-risk predators such as lizards and quolls from the devastating impacts of invasive cane toads.

Cane toads are invasive and highly toxic to Australia’s apex predators.
David Nelson

All across tropical Australia, the arrival of these gigantic alien toads has caused massive die-offs among meat-eating animals such as yellow-spotted monitors (large lizards in the varanid group) and quolls (meat-eating marsupials). Mistaking the new arrivals for edible frogs, animals that try to eat them are fatally poisoned by the toad’s powerful toxins.

Steep population declines in these predators ripple out through entire ecosystems.

But we can change that outcome. We expose predators to a small cane toad, big enough to make them ill but not to kill them. The predators learn fast, and ignore the larger (deadly) toads that arrive in their habitats a few weeks or months later. As a result, our trained predators survive, whereas their untrained siblings die.




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Conservation ‘on Country’

But it’s not easy science. The site is remote and the climate is harsh.

We and our collaborators, the Western Australian Department of Biodiversity, Conservation and Attractions, decided at the outset that we needed to work closely with the Indigenous Traditional Owners of the east Kimberley – the Balanggarra people.

So as we cruised across the floodplain on quad bikes looking for goannas, each team consisted of a scientist (university-educated, and experienced in wildlife research) and a Balanggarra Indigenous ranger.

Although our study species is huge – a male yellow-spotted monitor can grow to more than 1.7 metres in length and weigh more than 6kg – the animals are well-camouflaged and difficult to find.

Over an 18-month study, we caught and radio-tracked more than 80 monitors, taught some of them not to eat toads, and then watched with trepidation as the cane toad invasion arrived.




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Excitingly, the training worked. Half of our trained lizards were still alive by the end of the study, whereas all of the untrained lizards died soon after toads arrived.

That positive result has encouraged a consortium of scientists, government authorities, conservation groups, landowners and local businesses to implement aversion training on a massive scale (see www.canetoadcoalition.com), with support from the Australian Research Council.

A yellow-spotted monitor fitted with a radio transmitter in our study. This medium-sized male was trained and lived for the entirety of the study in high densities of cane toads.
Georgia Ward-Fear, University of Sydney



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Cross-cultural collaboration key to success

But there’s a twist to the tale, a vindication of our decision to make the project truly collaborative.

When we looked in detail at our data, we realised that the monitor lizards found by Indigenous rangers were different to those found by western scientists. The rangers found shyer lizards, often further away from us when sighted, motionless, and in heavy cover where they were very difficult to see.

Gregory Johnson, Balanggarra elder and ranger.
Georgia Ward-Fear

We don’t know how much the extraordinary ability of the rangers to spot those well-concealed lizards was due to genetics or experience – but there’s no doubt they were superb at finding lizards that the scientists simply didn’t notice.

And reflecting the distinctive “personalities” of those ranger-located lizards, they were the ones that benefited the most from aversion training. Taking a cautious approach to life, a nasty illness after eating a small toad was enough to make them swear off toads thereafter.

In contrast, most of the lizards found by scientists were bold creatures. They learned quickly, but when a potential meal hopped across the floodplain a few months later, the goanna seized it before recalling its previous experience. And even holding a toad briefly in the mouth can be fatal.

Comparisons of conditions under which lizards were initially sighted in the field by scientists and Indigenous rangers (a) proximity to lizards in metres (b) density of ground-cover vegetation (>30cm high) surrounding the lizard (c) intensity of light directly on lizard (light or shade) (d) whether the lizard was stationary or moving (i.e. walking or running). Sighting was considered more difficult if lizards were further away, in more dense vegetation, in shade, and stationary.
Georgia Ward-Fear, University of Sydney

As a result of the intersection between indigenous abilities and lizard personalities, the overall success of our project increased as a result of our multicultural team.

If we had just used the conventional model – university researchers doing all of the work, indigenous people asked for permission but playing only a minor role – our project could have failed, and the major conservation initiative currently underway may have died an early death.

So our study, now published in Conservation Letters, provides an unusual insight – backed up by evidence.

Moving beyond lip service, and genuinely involving Indigenous Traditional Owners in conservation research, can make all the difference in the world.

Georgia Ward-Fear (holding a yellow-spotted monitor) with Balanggarra Rangers Herbert and Wesley Alberts.
David Pearson, WA Department of Biodiversity, Conservation and Attractions

This research was published in collaboration with James “Birdy” Birch and his team of Balanggarra rangers in the eastern Kimberley.The Conversation

Georgia Ward-Fear, Post doctoral fellow and Conservation Ecologist , University of Sydney and Rick Shine, Professor in Evolutionary Biology, University of Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Squid team finds high species diversity off Kermadec Islands, part of stalled marine reserve proposal



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This squid belongs to one of the families (Histioteuthidae) that is highly diverse but was not previously recorded from the Kermadecs.
Richard Young, CC BY-SA

Kat Bolstad, Auckland University of Technology and Heather Braid, Auckland University of Technology

Squids and octopuses could be considered the “parrots of the ocean”. Some are smart, and many have complex behaviours. And, of course, they have strange, bird-like beaks.

They are the subject of ancient myths and legends about sea monsters, but they do not live for decades. In fact, their high intelligence and short lifespan represent an unusual paradox.

In our latest research we have discovered several new species that have never been reported from New Zealand waters. Our study almost doubles the known diversity for the Kermadec region, north of New Zealand, which is part of the proposed, but stalled, Kermadec–Rangitāhua ocean sanctuary.




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More than we bargained for

Collectively, squids and octopuses are known as cephalopods, because their limbs attach directly to their head (cephalus). Our team studies cephalopods in our part of the world – the waters between Antarctica and the most northern reaches of New Zealand, the Kermadec Islands – as well as further afield.

Our first inkling of an impressive regional diversity came as we began to open boxes of frozen cephalopod samples at the National Institute for Water and Atmospheric Research (NIWA). These animals had been collected during a deep-sea survey voyage to the Kermadec Islands to better understand the region’s marine biodiversity. Members of the AUT Lab for Cephalopod Ecology and Systematics (ALCES), also known as the “squid lab”, had come to identify and examine them.

As we gently defrosted each specimen, we marvelled at their perfect suckers, iridescent eyes, and shining light organs. We noticed that many species were rare among New Zealand collections. There were some familiar faces, but also some we had only rarely or never encountered before in our local waters. Some were known from neighbouring regions; others, we suspected, might be entirely new to science.

We examined them, photographed each one, took small samples of muscle tissue for DNA analysis, and preserved them for additional work in the future. Then we set about systematically comparing our observations with what had previously been reported in New Zealand waters. And we were in for a surprise.

Doubling known diversity

Among the 150 cephalopod specimens that were collected, we identified 43 species, including 13 species that had not been previously found anywhere in New Zealand waters. Three entire orders – the taxonomic rank above family, which is the level at which, for example, egg-laying mammals split off from all other living mammals – had not been reported from this region: “Bobtail squids” (sepiolids), “comb-fin squids” (genus Chtenopteryx, order Bathyteuthoidea), and myopsid squids (coastal squids with eyes covered by a cornea).

We extracted DNA and obtained sequences for the species that had been seen for the first time in New Zealand waters. This allows us to compare them with individuals from other regions of the world. These included the strange tubercle-covered “glass” (cranchiid) squid Cranchia scabra, and the little “ram’s horn squid” Spirula spirula.

Examples of squid specimens collected recently from the Kermadec Islands Ridge: A) Histioteuthis miranda, B) Heteroteuthis sp. ‘KER’ (likely new to science), C) Chtenopteryx sp. ‘KER1’ (likely new to science), D) Leachia sp. (likely new to science), E) Pyroteuthis serrata, F) Enoploteuthis semilineata. Scale bars: 5mm.
Images by Rob Stewart/Keren Spong, CC BY-ND

Five species appear likely new to science, across a number of families with colourful common names such as “strawberry” and “fire” squids (Histioteuthidae and Pyroteuthidae, respectively). These individuals were genetically distinct from all other specimens that had been previously identified and sequenced (by us or others). Their physical appearances will now need to be compared in detail with other similar-looking species in order to fully evaluate their taxonomic status.

In total, 28 of the species we encountered had not previously been reported in the Kermadecs. This brings the total number of species in the region to at least 70. Of these, half are not known to occur elsewhere in New Zealand waters.

Kermadec–Rangitāhua Ocean Sanctuary

The Kermadec Islands, north-north-east of New Zealand, represent a diverse and nearly pristine environment. The region includes (among other habitats) a chain of seamounts and the second-deepest ocean trench in the world.

Currently, the Kermadec Islands region is on a tentative list of UNESCO World Heritage Sites. A small proportion of the area is already protected by an existing marine reserve, which extends 12 nautical miles around each of five islands and pinnacles.

This map shows New Zealand’s Exclusive Economic Zone (EEZ) in light grey, the existing Kermadec Islands marine reserve in dark grey, and the proposed Kermadec–Rangitāhua Ocean Sanctuary outlined in black.
Heather Braid, Kat Bolstad, CC BY-ND

The proposed Kermadec–Rangitāhua Ocean Sanctuary would extend the protection to 200 nautical miles and protect 15% of New Zealand’s ocean environment. It would be among the world’s largest marine protected areas.




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We strongly support the establishment of the proposed sanctuary, especially since most of the cephalopod taxa newly reported by this research are deep-sea species whose habitat is not protected by the existing marine reserve.

Although the creation of the sanctuary is supported by most political parties, New Zealand First, which is part of the government coalition, opposes it. So does the fishing industry because fishing would be banned. It is possible that the sanctuary might be created with a lower level of protection than originally proposed (with some fishing still permitted), but the government has reached an impasse.

If the Kermadec–Rangitāhua ocean sanctuary were to be established, it would protect habitats that are used by over half of the known squid and octopus biodiversity in New Zealand waters, including 34 species that have so far only been reported from the Kermadec region.The Conversation

Kat Bolstad, Senior Lecturer, Auckland University of Technology and Heather Braid, Postdoctoral Research Fellow, Auckland University of Technology

This article is republished from The Conversation under a Creative Commons license. Read the original article.