Dingo wrongly blamed for extinctions

Dingo , Fraser Island. Image – ogwens/Flickr

Dingoes have been unjustly blamed for the extinctions on the Australian mainland of the Tasmanian tiger (or thylacine) and the Tasmanian devil, a University of Adelaide study has found.

In a paper published in the journal Ecology, the researchers say that despite popular belief that the Australian dingo was to blame for the demise of thylacines and devils on the mainland about 3000 years ago, in fact Aboriginal populations and a shift in climate were more likely responsible.

“Perhaps because the public perception of dingoes as ‘sheep-killers’ is so firmly entrenched, it has been commonly assumed that dingoes killed off the thylacines and devils on mainland Australia,” says researcher Dr Thomas Prowse, Research Associate in the School of Earth and Environmental Sciences and the Environment Institute.

“There was anecdotal evidence too: both thylacines and devils lasted for over 40,000 years following the arrival of humans in Australia; their mainland extinction about 3000 years ago was just after dingoes were introduced to Australia; and the fact that thylacines and devils persisted on Tasmania, which was never colonised by dingoes.

“However, and unfortunately for the dingo, most people have overlooked that about the same time as dingoes came along, the climate changed rather abruptly and Aboriginal populations were going through a major period of intensification in terms of population growth and technological advances.”

The researchers built a complex series of mathematical models to recreate the dynamic interaction between the main potential drivers of extinction (dingoes, climate and humans), the long-term response of herbivore prey, and the viability of the thylacine and devil populations.

The models included interactions and competition between predators as well as the influence of climate on vegetation and prey populations.

The simulations showed that while dingoes had some impact, growth and development in human populations, possibly intensified by climate change, was the most likely extinction driver.

“Our multi-species models showed that dingoes could reduce thylacine and devil populations through both competition and direct predation, but there was low probability that they could have been the sole extinction driver,” Dr Prowse says.

“Our results support the notion that thylacines and devils persisted on Tasmania not because the dingo was absent, but because human density remained low there and Tasmania was less affected by abrupt climate changes.”

The study ‘An ecological regime shift resulting from disrupted predator-prey interactions in Holocene Australia’ also involved Professors Corey Bradshaw and Barry Brook from the University of Adelaide’s Environment Institute and Professor Chris Johnson from the University of Tasmania.

Prof Peter Ward podcast available

Professor Peter Ward

The podcast from the presentation by Professor Peter Ward is now available for download.

Peter D. Ward, Ph.D, is a paleontologist and professor in the Departments of Geology and Biology at the University of Washington in Seattle. He also serves as an adjunct professor of zoology and astronomy. His research specialties include the Cretaceous–Tertiary extinction event and mass extinctions generally. His books include the best-selling “Rare Earth: Why Complex Life Is Uncommon in the Universe” (co-author Donald Brownlee, 2000), “Under a Green Sky: Global Warming, the Mass Extinctions of the Past, and What They Can Tell Us About Our Future” (2007), and “The Medea Hypothesis: Is Life on Earth Ultimately Self-Destructive?” (2009).

A taxonomy of mass extinctions based on new geobiological research in the Gondwana Continents

Mass extinctions have been the subject of intense curiosity and study from the dawn of the discipline of Geology as a modern science.  The topic has informed (or clashed) with fundamental principles of Geology through its history, including Catastrophism, Uniformitarianism, and most recently a nascent “Neocatastrophism”.  In this talk Professor Peter Ward will communicate new information from  geobiological research by his group that pertains to this debate.

Specific new data coming from research into the K/Pg mass extinction at field sites in Antarctica, the late Devonian mass extinction based on work just finished in the Canning Basin of Australia, and the Permian mass extinction from new work in both South Africa and Western Canada.  The talk will conclude with a rough attempt at proposing a “taxonomy” of mass extinction causes.

Listen to the podcast

Making national parks truly national.

Kakadu National Park – Flickr/Marc Dalmulder

Environment Insitute member Corey Bradshaw co-authored this piece on The Conversation on June 14, 2013.

Australia boasts over 500 national parks covering 28 million hectares of land, or about 3.6% of Australia. You could be forgiven for thinking we’re doing well in the biodiversity-conservation game.

But did you know that of those more than 500 national parks, only six are managed by the Commonwealth Government? For marine parks, it’s a little more: 61 of the 130-plus are managed primarily by the Commonwealth. This means that the majority of our important biodiversity refuges are managed exclusively by state and territory governments. In other words, our national parks aren’t “national” at all.

In a world of perfect governance, this wouldn’t matter. But we’re seeing the rapid “relaxation” of laws designed to protect our “national” and marine parks by many state governments. Would making all of them truly national do more to conserve biodiversity?

One silly decision resulting in a major ecosystem disturbance in a national park can take decades if not hundreds of years to heal. Ecosystems are complex interactions of millions of species that take a long time to evolve – they cannot be easily repaired once the damage is done.

The full article can be accessed here.

Endangered species: could better tracking methods reduce vulnerability or extinction?

Palau. Image by LuxTonnerre, licensed under Creative Commons.

Guest blogger botanist Craig Costion has written an article on endangered species on Biodiversity Revolution‘s blog which describes a new approach to developing the International Union for Conservation of Nature’s (IUCN) classification for potentially endangered species for which no demographic information is available.

The term ‘endangered species’ refers to species which fall under the IUCN’s Red List, a complete list of all endangered mammals, birds, amphibians, sharks, reef-building corals, cycads and conifers, but only a small percentage of all species of reptiles, fishes, and selected groups of plants and invertebrates have been classified.

Currently the IUCN classifies a species or habitat as ‘vulnerable’ if it has suffered a 30% decline ‘over 3 generations or within 100 years’. The author believes it is important to classify the remaining species to include ‘information on the history of habitat modification and destruction extending over and beyond 100 years’ to obtain a greater understanding of species vulnerability.

The full findings and methods are available in the post entitled Endangered Species by Craig Costion.

New Paper – No need for disease: testing extinction hypotheses for the thylacine using multi-species metamodels

A new paper involving Environment Institute members Thomas Prowse, Corey Bradshaw (also SARDI), Michael Watts and Barry Brook as well as Christopher Johnson (University of Tasmania), Robert Lacy (Chicago Zoological Society) and John Pollak (Cornell University) has recently been published in the Journal of Animal Ecology.

The paper titled ‘No need for disease: testing extinction hypotheses for the thylacine using multi-species metamodels’ designed a new population viability approach (PVA) that includes species interactions explicitly by networking species models within a single ‘metamodel’.

Thylacine Thylacinus cynocephalus
Image: Kelly Garbato (Flikr)

Population viability analysis (PVA) is used to assess the extinction risk of threatened species and to evaluate different management strategies. However, conventional PVA neglects important biotic interactions and therefore can fail to identify important threatening processes.

This study demonstrates the utility of PVA metamodels by using them to reinterpret the extinction of the carnivorous, marsupial thylacine Thylacinus cynocephalus (Tasmanian Tiger) in Tasmania. In particular, they test the claim that well-documented impacts of European settlement cannot account for this extinction and that an unknown disease must have been an additional and necessary cause.

Read the paper to find out more.

 

Ancient genes may explain modern threat to Tasmanian devils

Researchers at the University of Sydney and the University of Adelaide have discovered that Tasmanian devils had low immune gene diversity for hundreds, and possibly thousands, of years before the emergence of Devil Facial Tumour Disease.

The study, published today in the journal Biology letters, involves Environment Institute member Jeremy Austin from the Australian Centre for Ancient DNA. The study was led by Associate Professor Kathy Belov from the University of Sydney’s Faculty of Veterinary Science and also involved senior author Katrina Morris, a PhD candidate at the University of Sydney.

“It is well known that low genetic diversity is a major extinction risk factor, but when and how devils lost their immune diversity has remained a mystery until now,” said senior author Katrina Morris, a PhD candidate at the University of Sydney.

Dr Jeremy Austin from the Australian Centre for Ancient DNA

“Devils once lived across much of mainland Australia, but became extinct sometime in the last few thousand years,” said Dr Jeremy Austin, from the Australian Centre for Ancient DNA.

“We looked at subfossil bones of these extinct mainland devils, as well as museum specimens of Tasmanian devils collected over the last 200 years. They capture the genetic diversity of the past allowing us to see how the immune gene diversity has changed over thousands of years.”

The research was supported by funding from the Australian Research Council, the Save the Tasmanian Devil Foundation and Zoos SA.

Read the full Media Release on the University of Sydney’s website to find out more.

A new measure for species extinction threat.

A new index has been developed to help conservationists better understand how close species are to extinction.

The index, developed by a team of Australian researchers from the University of Adelaide and James Cook University, is called SAFE (Species Ability to Forestall Extinction).

The SAFE index builds on previous studies into the minimum population sizes needed by species to survive in the wild. It measures how close species are to their minimum viable population size.

“SAFE is a leap forward in how we measure relative threat risk among species,” says co-author Professor Corey Bradshaw, Director of Ecological Modelling at the University of Adelaide’s Environment Institute.

“The idea is fairly simple – it’s the distance a population is (in terms of abundance) from its minimum viable population size. While we provide a formula for working this out, it’s more than just a formula – we’ve shown that SAFE is the best predictor yet of the vulnerability of mammal species to extinction.”

Professor Bradshaw says SAFE is designed to be an adjunct to the International Union for Conservation of Nature (IUCN) Red List of Threatened Species, not a replacement.

“Our index shows that not all Critically Endangered species are equal. A combined approach – using the IUCN Red List threat categories together with the SAFE index – is more informative than the IUCN categories alone, and provides a good method for gauging the relative ‘safety’ of a species from extinction,” he says.

Of the 95 mammal species considered in the team’s analysis, more than one in five are close to extinction, and more than half of them are at ‘tipping points’ that could take their populations to the point of no return.

“For example, our studies show that practitioners of conservation triage may want to prioritise resources on the Sumatran rhinoceros instead of the Javan rhinoceros. Both species are Critically Endangered, but the Sumatran rhino is more likely to be brought back from the brink of extinction based on its SAFE index,” Professor Bradshaw says.

“Alternatively, conservationists with limited resources may want to channel their efforts on saving the tiger, a species that is at the ‘tipping point’ and could have reasonable chance of survival.”

The SAFE index is detailed in a new paper published this month in the journal Frontiers in Ecology and Environment (http://dx.doi.org/10.1890/100177). It is co-authored by Reuben Clements (James Cook University), Professor Corey Bradshaw and Professor Barry Brook (The University of Adelaide) and Professor Bill Laurance (James Cook University).

A private secluded reef not so idyllic – for fish

Isolation a threat to Great Barrier Reef fish

At first glance it may seem like a good idea to be a fish living the quiet life on a small and isolated reef. But a team of researchers has found that the opposite is the case on Australia’s Great Barrier Reef. Using 15 years of long-term monitoring data collected from 43 reefs by the Australian Institute of Marine Science (AIMS), the researchers from AIMS and the University of Adelaide have found that fish living on small, isolated reefs face a greater risk of local extinction. The results have been published in Ecology, the journal of the Ecological Society of America.

“Our results support the idea that small and isolated reefs are more susceptible to local species extinctions because of the tendency for their fish populations to be more variable,” says project leader Dr Camille Mellin, a Postdoctoral Fellow from AIMS and the University of Adelaide’s Environment Institute.”Isolated reefs receive relatively fewer ‘immigrant’ fish from adjacent reefs. If there is a disturbance to the population, such as a cyclone or coral bleaching, fish species on isolated reefs are much slower to recover. These populations are not as resilient to changes and are not easily replenished, increasing their probability of extinction.” By contrast, larger, more populated reefs see fewer large fluctuations in the fish population. This is partly due to the increased competition between species, and partly because of predators, which keep the population size in check.

“Our research suggests that conservation resources might be better allocated to the protection of large, connected habitats,” Dr Mellin says. As a result of the research, a map has been produced predicting the patterns of variability of coral reef fish species on the Great Barrier Reef. “This new map is a potential new tool for the managers of the Great Barrier Reef Marine Park, but it’s important to emphasise that it is just one tool. When making management decisions for the Reef, a whole range of issues needs to be taken into account,” Dr Mellin says.

Professor Corey Bradshaw, Director of Ecological Modelling at the University of Adelaide, says the research is “an essential piece in the marine planning puzzle”. “If data for other reefs around the world become available, it would be possible to assess threats to species in those parts of the world using the same techniques,” he says. “Our research also demonstrates the need for long-term data sets,” says Dr Julian Caley, Principal Research Scientist at AIMS. “This work would not have been possible without AIMS’ commitment to the long-term monitoring of the Great Barrier Reef. This dataset is unique in the world and the only one that would have made this study possible.”

The Great Barrier Reef is the world’s largest reef system, composed of more than 2900 individual reefs and 900 islands stretching for more than 2600 km.

“Four in 40” Barry Brook Podcast Now Available

Barry Brook’s 10 minute presentation for the latest Four in 40 series is now available as a podcast.

“Four in 40” is a collaboration between The University of Adelaide and the DWLBC, where 4 speakers each speak for 10 minutes on their research and its implications for policy (and vice versa), followed by discussion.

The idea is to expose people in both organisations (and beyond) to what is happening and to make useful connections.  This series follows on from a successful event held in April, with the second program for this year held on Tuesday 8th June.

The topic was climate change and water management and the speakers were:

• Barry Brook – climate change and multi-species extinction modelling, The University of Adelaide PODCAST AVAILABLE HERE
• James Hall – climate change and land capability assessment, DWLBC
• Steve Barnett – climate change and groundwater availability, DWLBC
• Matt Gibbs – climate change and minimising the carbon footprint of water infrastructure and incorporating climate variability into hydrological modelling, The University of Adelaide

Future “Four in 40” events will have themes of modelling and communication in science.