Crying wolf: limitations of predator–prey studies need not preclude their salient messages

Authors: Euan G Ritchie, Jannik Schultner, Dale G Nimmo, Joern Fischer, Jan Hanspach, Tobias Kuemmerle, Laura Kehoe and Ine Dorresteijn

Published in: Proceedings of the Royal Society B, volume 283, issue 1834 (July 2016)

A rapidly growing body of the literature reveals the important roles apex predators play in shaping the composition and functioning of ecological communities worldwide.

The principal effects of apex predators — namely herbivore and mesopredator population suppression — are often evident following their removal from environments, or their reintroduction, including rewilding initiatives. What remains less clear, however, is to what extent humans versus other apex predators affect ecosystems, how both interact across gradients of anthropogenic pressure and how such interactions can be affected by underlying bottom-up processes.

Such questions are critical to answer in the Anthropocene, where effective management of ecosystems and conservation of biodiversity requires a better understanding of how top-down and bottom-up processes vary according to anthropogenic influences…

Ritchie EG, Schultner J, Nimmo DG, Fischer J, Hanspach J, Kuemmerle T, Kehoe L, Dorresteijn I (2016) rying wolf: limitations of predator–prey studies need not preclude their salient messages, Proceedings of the Royal Society B, 283:1834 PDF DOI

Concordance in phylogeography and ecological niche modelling identify dispersal corridors for reptiles in arid Australia

Authors: Jane Melville, Margaret L Haines, Joshua Hale, Stephanie Chapple and Euan G Ritchie

Published in: Journal of Biogeography (early access)

Abstract

Using the rock-specialist agamid Ctenophorus caudicinctus as a model, we test hypothesized biogeographical dispersal corridors for lizards in the Australian arid zone (across the western sand deserts), and assess how these dispersal routes have shaped phylogeographical structuring in arid and semi-arid Australia.

We sequenced a c. 1400 bp fragment of mtDNA (ND2) for 134 individuals of C. caudicinctus as well as a subset of each of the mtDNA clades for five nuclear loci (BDNF, BACH1, GAPD, NTF3, and PRLR). We used phylogenetic methods to assess biogeographical patterns within C. caudicinctus, including relaxed molecular clock analyses to estimate divergence times. Ecological niche modelling (Maxent) was employed to estimate the current distribution of suitable climatic envelopes for each lineage.

Phylogenetic analyses identified two deeply divergent mtDNA clades within C. caudicinctus – an eastern and western clade – separated by the Western Australian sand deserts. However, divergences pre-date the Pleistocene sand deserts. Phylogenetic analyses of the nuclear DNA data sets generally support major mtDNA clades, suggesting past connections between the western C. c. caudicinctus populations in far eastern Pilbara (EP) and the lineages to the east of the sand deserts. Ecological niche modelling supports the continued suitability of climatic conditions between the Central Ranges and the far EP for C. c. graafi.

Estimates of lineage ages provide evidence of divergence between eastern and western clades during the Miocene with subsequent secondary contact during the Pliocene. Our results suggest that this secondary contact occurred via dispersal between the Central Ranges and the far EP, rather than the more southerly Giles Corridor. These events precede the origins of the western sand deserts and divergence patterns instead appear associated with Miocene and Pliocene climate change.

Melville J, Haines ML, Hale J, Chapple S, Ritchie EG (2016) Concordance in phylogeography and ecological niche modelling identify dispersal corridors for reptiles in arid Australia. Journal of Biogeography PDF DOI

 

3AW: Deakin University ecologist calls for Australians to eat differently

I spoke with Tom Elliot on 3AW Drive. My topic: Australians should consider eating kangaroos and camels as opposed to sheep and cows. Maybe one day in the future, introduced pests such as cane toads and European carp could end up on our dinner plates, instead of wreaking havoc with our environment.

Nutritious, delicious... cane toad!? Image credit Brian Gatwicke via Wikimedia Commons

Nutritious, delicious… cane toad!? Image credit Brian Gatwicke via Wikimedia Commons

3AW website

The Conversation: Eat locals: swapping sheep and cows for kangaroos and camels could help our environment

By Euan Ritchie (Deakin University) and Adam Munn (University of New South Wales)

A six-legged diet? Insects are often high in protein and low in fat, and can be produced in large numbers, efficiently and quickly. Image credit Shutterstock

A six-legged diet? Insects are often high in protein and low in fat, and can be produced in large numbers, efficiently and quickly. Image credit Shutterstock

We may be what we eat, but our dietary choices also affect the health of the environment, and farmers’ back pockets.

Energy and water use, native habitat cut down for crops and grazing, and emissions that exacerbate climate change, are just some of the profound effects agriculture has on Earth. And, there are more and more mouths to feed.

Perversely, both starvation and obesity are severe health issues across the world. With agriculture confronted by economic and environmental uncertainties, society faces enormous challenges.

But challenges also offer great opportunities. Drastically rethinking what we eat, and where and how food is produced, could help our health, the planet, and our farming businesses.

That means eating fewer sheep and cows, and more kangaroos, feral animals, and insects.

Unsustainable farming

Australia’s rangelands — the drier regions of the country predominantly used for livestock and grazing — cover about 80% of the country. They are often in poor condition and economically unviable. In part, this is due to the fact we still farm many animals, mostly in ways that are unsuited to the Australian climate and environment.

Hard-hoofed animals contribute to soil compaction and erosion, and have even been linked to the spread of the invasive cane toad. But the environmental impact of intensive stock farming extends much further.

Continuing to farm using a European-derived, intensive system is a recipe for land degradation and environmental collapse, especially with the compounding impacts of climate change (severe weather events, more frequent and intense droughts, and fires).

Past and current agricultural practices have also profoundly altered our environment. It may be impossible to restore these lands to their original condition, so we must learn to operate in the new environment we’ve created.

More broadly, many experts have identified our meat consumption and intensive farming as a significant driver of global problems.

Treading lightly

To address these issues, we need a cultural shift away from intensive agriculture. The days of riding and relying on the sheep’s back, cattle’s hoof, or the more recent, and increasingly popular, chicken’s wing, may need to pass.

Native wildlife and some feral animals tread more lightly on the environment than intensively produced livestock do, and thus provide more sustainable options for food production on Australia’s arid lands. Kangaroos and goats place one-third of the pressure on grazing lands compared with sheep.

We already eat some of these animals, but could arguably eat more of them, including feral goats, camels, deer, rabbits, pigs, and buffalo, as well as native emus and kangaroos.

Yet more extreme proposals could include feral donkeys, cats, horses; and even cane toads. Horses are already consumed in Europe and cats in central Australia.

Eating more feral and native animals, and relying less on chicken, sheep, domestic pigs, and cattle would help meet ethical concerns too. Wild animals such as kangaroos are killed quickly, without the extended stress associated with industrialised farming, containment, and transportation to abattoirs.

And by harvesting sometimes overabundant wild native animals (such as kangaroos) and feral species, we may be able to reduce their impacts on ecosystems, which include overgrazing and damage to waterways.

An even greater leap would be to eat fewer four-limbed animals and more six-legged creatures. Insects are often high in protein and low in fat, and can be produced in large numbers, efficiently and quickly. They are already consumed in large numbers in some regions, including Asia.

Evidence that a market for such a food revolution exists is that shops are already popping up selling mealworm flour, ant seasoning salt, and cricket protein powder, among other delicacies.

Boom and bust

Thanks to Australia’s variable climate, swinging between drought and flood, many farms are also tied to a boom-and-bust cycle of debt and credit.

As the climate becomes increasingly unpredictable, this economic strategy must be detrimental to the farmers, and is shown by many farm buy-backs or sell-offs.

It makes sense to use species that are naturally more resilient and able to respond to boom-and-bust cycles. Kangaroos and other species can forage on our ancient and typically nutrient-poor soils without the need for nutritional supplements (such as salt licks), and are physiologically more efficient at conserving water. This could lead to a more sustainable supply of food and income for farmers, without the dizzying economic highs but also without the inevitable prolonged and despairing lows.

Future-proofing

To be clear, we are not suggesting completely replacing livestock, but diversifying and tailoring enterprises to better suit Australia’s environment.

To support more diverse agricultural enterprises we will need to overcome many obstacles, such as licences to hunt, what we’re comfortable consuming, and land use regulation. But we shouldn’t shy away from these challenges. There are tremendous opportunities for rural, regional and Indigenous communities, and indeed cities too.

We need a more diverse mix of meat to adapt to the pressures of a growing population and climate change. Supermarket aisles that display beef, chicken, pork and lamb, alongside kangaroo, camel, deer, goat, and insects, could be just what the environmental, health and economic doctors ordered.

This article was originally published on The Conversation. Read the original article online, including reader comments.

The Conversation

 

The Conversation: Nature is neglected in this election campaign – at its and our own peril

By Don Driscoll and Euan Ritchie (Deakin University).

The electioneering has begun. In a campaign set to be dominated by economic issues, the Coalition and Labor are locking horns over who can best manage our finances, protect jobs and make housing more affordable. The Greens predictably decry the major parties, including their cavalier climate-change policies.

These are important issues, but are they highest priority on the political agenda? An arguably even greater issue exists that nobody is seriously championing, but which impacts all of us, socially, environmentally and economically.

Our natural heritage – the plants, animals and other organisms that help define Australia’s identity – are in dire straits. Yet this biodiversity crisis is barely mentioned in political discourse, nor is it foremost in the public consciousness.

Everlastings in the Australian Alps. But will they be? Image credit: John O'Neill via Wikimedia Commons

Everlastings in the Australian Alps. But will they be? Image credit: John O’Neill via Wikimedia Commons

The world economy is losing €50 billion (A$73 billion) a year through lost ecosystem services. It is predicted to lose €14 trillion per year by 2050 without action now. With potentially 7% of global economic product at stake by mid-century, nature conservation must surely be on the agenda in this election.

Actions needed to conserve our natural heritage, and reap substantial rewards, will challenge some of our most cherished ideas about social and economic policy. This demands reforms to reverse creeping losses to our democratic process.

Looking at the major parties’ platforms, it is clear that nature is not on the agenda. Labor lists 23 positive policies, none of which deals directly with conserving Australia’s plants and animals. The Liberal-National Party has done slightly better, claiming to believe in preserving Australia’s natural beauty and environment for future generations. However, its federal platform, released last year, shows no evidence of this belief.

Public concern has also shifted away from nature issues and towards other concerns like terrorism, as well as traditional areas of focus such as health care and the economy. This shift can be seen in some surprising places, such as the major grassroots lobby group GetUp – of its ten current campaigns only one, the Great Barrier Reef program, is directly about conserving wildlife diversity.

Environmental riches, but for how long?

The value of biodiversity to humans is well established (for example, see here, here, and here). Biodiversity reduces stress, crime and disease. It also provides new economic opportunities and many other benefits, from climate control, to flood defence, to the many benefits delivered by birds.

These are just the tip of the iceberg, but like the polar ice they are at risk of disappearing through our neglect.

Despite biodiversity’s immense value, Australia’s natural heritage is not assured. Good news stories exist,
but as a succession of government State of the Environment reports over recent decades has shown, our natural heritage continues to be squandered.

The reports cite population growth, economic growth and climate change as key drivers of decline. Land clearing and invasive species also lead to biodiversity loss. All must be addressed to reverse the alarming trajectory of our wildlife.

These threats to our natural heritage should be high on the political agenda. But despite recent extinctions, caused in no small part by a failure to act quickly on conservation advice, bureaucrats and politicians have failed to rise to the challenge. Australia’s plants, animals and other wildlife continue to be swept aside with an enthusiasm and abandon reminiscent of the 19th-century pioneers.

Why the lack of action?

Nature is missing in action from the political agenda for many reasons. Here are two key ones: questionable political donations and processes, and the gagging of the public service, government and university scientists. Both issues go to the heart of our democracy.

Australia has some of the weakest electoral laws concerning political donations and spending. Time lags between receiving donations and declaring them means that appropriate scrutiny of policy motivations, particularly at election times, is uncommon. This is concerning, because links between political favours for donors, while hard to prove, are frequently noted.

These correlations are not surprising. Corporate political activities are typically not gestures of goodwill, but a widely accepted corporate strategy aimed at securing better outcomes. Because many companies depend on using land for activities such as digging up resources and clearing native vegetation, the success of their political donations can often be reflected in damage to nature.

Equally concerning is the deafening silence from people who really know how damaging government policies can be for the environment. Inconvenient truths might challenge government policies. So public servants, including government scientists, are prohibited from speaking, or tweeting. Governments will go to extremes more often seen in the pages of crime thrillers to track down and punish whistle-blowers.

Governments attempting to silence academics hit the spotlight over cattle grazing trials in Victorian national parks. A senior Victorian public servant reportedly threatened to withdraw further funding from the University of Melbourne if the university did not agree to oversee the government’s grazing trial, despite the trial being widely regarded as flawed and unnecessary. Faced with this type of pressure, many university scientists simply avoid public debate for fear of damaging their job prospects or government funding.

In this climate of silence, major biodiversity issues and damaging government policies aren’t appropriately aired. The public don’t hear about it and so can’t make informed decisions at the polling booth. Consequently, government and public service barriers to honest media coverage undermine an informed democracy.

Valuing and preserving nature are critical for our well-being and prosperity, but species continue disappearing at alarming rates to causes we could better manage.

There are things that can be done, at a political level, to help stop this erosion of Australia’s natural heritage before it’s too late. In addition to adequately funding conservation, we should reform political funding rules. We should also encourage, even legally require, honest and open disclosure of how government policy impacts our environment.

This article was originally published on The Conversation. Read the original article online, including reader comments.

The Conversation

 

Stop jumping the gun: A call for evidence-based invasive predator management

Authors: Tim S Doherty and Euan G Ritchie

Published in: Conservation Letters (early access)

Abstract

Invasive mammalian predators are major drivers of species extinctions globally.

To protect native prey, lethal control is often used with the aim of reducing or exterminating invasive predator populations. The efficacy of this practice however is often not considered despite multiple practical and ecological factors that can limit success.

Here, we summarise contemporary knowledge regarding the use and challenges of lethal control and alternative approaches for reducing invasive predator impacts.

As the prevailing management approach, we outline four key issues that can compromise the effectiveness of lethal control: release of herbivore and mesopredator populations; disruption of predator social systems; compensatory predator immigration; and ethical concerns.

We then discuss the relative merits and limitations of four alternative approaches that may enhance conservation practitioner’s ability to effectively manage invasive predators: top-predator conservation or reintroduction; maintaining habitat complexity; exclusion fencing; and behavioural and evolutionary ecology.

Considerable uncertainty remains regarding the effectiveness of management approaches in different environmental contexts.

We propose that the deficiencies and uncertainties outlined here can be addressed through a combination of adaptive management, expert elicitation, and cost-benefit analyses.

Improved management of invasive predators requires greater consideration and assessment of the full range of management approaches available.

Doherty TS, Ritchie EG (2016) Stop jumping the gun: A call for evidence-based invasive predator management. Conservation Letters PDF DOI