Although I have incorporated a Cartoon of the Week feature on ConservationBytes.com, I think it’s worthwhile summarising them from time to time. So, continuing the Cartoon guide to biodiversity loss series with instalment 5 (see also instalments 1, 2, 3, and 4).
Just a plug for Richard Dawkins’ new book “The Greatest Show on Earth“. Hard to believe, but there are still billions of people who are blind to how life actually works, mainly from the intellectual blindfold of religion.
For more things Dawkins, visit http://richarddawkins.net/.
Here’s a nice little review from the increasingly impressive Frontiers in Ecology and the Environment which seems to be showcasing a lot of good conservation research lately.
© USGS
As we know, the world’s oceans are under huge threat, with predictions of 70 % loss of coral reefs by 2050, decline in kelp forests, loss of seagrasses, over-fishing, pollution and a rapidly warming and acidifying physical environment. Given all these stressors, it is absolutely imperative we spend a good deal of time thinking about the right way to impose restrictions on damage to marine areas – the simplest way to do this is via marine protected areas (MPA).
The science of MPA network design has matured over the last 10-20 years such that there is a decent body of literature now on what we need to do (now the policy makers just have to listen – some progress there too, but see also here). McLeod and colleagues in the latest issue of Frontiers in Ecology and the Environment have published a review outlining the best, at least for coral reefs, set of recommendations for MPA network design given available information (paper title: Designing marine protected area networks to address the impacts of climate change). Definitely one for the Potential list.
Here’s what they recommend:
Size
Shape
Representation
Replication
Spread
Critical Areas
Connectivity
Ecosystem Function
Ecosystem Management
Of course, this is just a quick-and-dirty list as presented here – I highly recommend reading the review for specifics.
McLeod, E., Salm, R., Green, A., & Almany, J. (2009). Designing marine protected area networks to address the impacts of climate change Frontiers in Ecology and the Environment, 7 (7), 362-370 DOI: 10.1890/070211
In a bid to save some time given looming grant application deadlines and overdue paper revisions, I’ve opted to reproduce a nice little discussion about how we define ‘species’ in a biodiversity sense. This is a great little synopsis of the species concept by Professor Colin Groves of the Australian National University that aired on ABC Radio National‘s Ockham’s Razor show hosted by Robyn Williams. This is an important discussion because it really dictates how we measure biodiversity, and more importantly, how we should seek to restore it when ‘degraded’. The full transcript can be viewed here, and you can listen here. Below I reproduce the relevant bits of the essay.
Species, in the words of the great evolutionary biologist George Gaylord Simpson, are lineages evolving separately from others, each with its own unitary evolutionary role and tendencies. They are the units of biodiversity. Everybody uses the term, with greater or lesser degrees of precision, but even biologists, I regret to say, often use it without actually defining what they mean.
It was the great zoologist Ernst Mayr who in 1940 offered the best known definition: ‘A species is a group of actually or potentially interbreeding natural populations which is reproductively isolated from other such groups’. He called this the Biological Species Concept.
This definition of species, still widely accepted, has frequently been misinterpreted as meaning that ‘different species cannot interbreed’. It does not say this. In the first place, it refers to species as ‘natural populations’. It is referring to what happens in a state of nature, not what happens in zoos or in domestic animals. For example, lions and leopards, which although closely related are usually recognised as different species, live in the same habitats in Africa and India and, as far as I know, no authenticated hybrids are known from the wild. But in zoos, hybrids have been bred successfully.
Then there is the question of what exactly ‘reproductive isolation’ consists of. Mayr said that the mechanisms of reproductive isolation may be either pre-mating (where members of different species do not normally regard each other as potential mates) or post-mating (where they do mate, but the hybrids do not survive, or are sterile). In the case of lions and leopards, evidently the reproductive isolating mechanisms are pre-mating, because normally they do not regard each other as potential mates, but these can break down if a male of one species and a female of the other are caged together, a case of making the best of a bad job, if you like. Their post-mating reproductive isolation, however, is incomplete: male lion-leopard hybrids are thought to be sterile, but the females are fertile.
So far so good. According to the Biological Species Concept, different species are defined by not usually forming hybrids with each other, for whatever reason, under natural conditions. But it is not so simple.
Consider leopards, again. They live not only in Africa and India, but also on the island of Sri Lanka, and throughout Southeast Asia, including the island of Java. The leopards of Sri Lanka and Java obviously do not interbreed with those of the mainland, because they are separated by water barriers. According to Ernst Mayr’s definition, species are ‘actually or potentially interbreeding natural populations’, and presumably island leopards are to be regarded as ‘potentially interbreeding’ with mainland ones. But how do we know? How could we possibly know?
© J. Dougherty
The closest relative of the lion and the leopard is the jaguar, which lives in South and Central America, and likewise doesn’t have the chance to interbreed with leopards (or with lions, for that matter), so again, the ‘potentially interbreeding’ criterion breaks down. I would ask, and it is legitimate to ask, why is the jaguar classified as a species separate from the African and mainland-Asian leopard, whereas the Sri Lankan and Javanese leopards are not?
In my opinion, ‘potentially interbreeding’, is, really, a phantom concept. The Biological Species Concept offers no guidance at all for deciding whether populations living in different areas are distinct species or not. As one example from my own experience, mammal specialists have had heated discussions over whether the American bison and the European bison are or are not different species, a particularly pointless exercise if one accepts the Biological Species Concept. It was as early as the 1960s that a few taxonomists began to worry about this, because they were starting to realise that there were quite a lot of cases where they really needed to know. Gilbert’s potoroo, from the south-west of Western Australia, is it, or is it not, a different species from the Long-nosed potoroo, from south-eastern Australia? This may sound like a piece of pedantry, but it is in fact not a trivial decision, because Gilbert’s potoroo is critically endangered, and if it is not really a distinct species then it is less of a worry.
It was a group working in the American Museum of Natural History, known as the New York Group and already getting a reputation for asking awkward questions, that was pushing most strongly for a resolution, and in 1983, one of them, the ornithologist Joel Cracraft, proposed to replace the Biological Species Concept altogether and define a species ‘The smallest cluster of individual organisms within which there is a parental pattern of ancestry and descent, and that is diagnosably distinct from other such clusters by a unique combination of fixed character states’. What this means is that a species is a population or group of populations (this is the ‘parental pattern of ancestry and descent’ bit) which can be distinguished 100% from any other (this is the ‘diagnosably distinct’ bit). This concept of species is called the Phylogenetic Species Concept.
Many biologists, myself included, I’m afraid, started off by disliking the Phylogenetic Species Concept, and hoped it would die a natural death. But it did not; in fact it spread because many biologists, including taxonomists, and at long last I too, realised that it provides an objective criterion, diagnosability, for all cases, which the old Biological Species Concept does not. It tells us, for example, that Sri Lankan and Javanese leopards are not distinct species, because they cannot be 100% distinguished from the leopards of the mainland, whereas the jaguar is a distinct species because it is 100% distinct from its relatives.
© P. Mays
Much taxonomy today depends on molecular genetics, DNA sequencing. At present, many molecular geneticists tend to distinguish species rather subjectively, if they differ ‘enough’, though what is meant by ‘enough difference’ varies from one study to another. The Phylogenetic Species Concept is of course excellently suited to DNA sequencing, and many species have been recognised by having consistent differences in DNA sequences (the diagnosability criterion).
The molecular revolution has also taught us something important about species, that they do in fact interbreed under natural conditions, to a much greater extent than we had thought. We know this, because there is a form of DNA, mitochondrial DNA, that is inherited not from both parents, but from the mother alone; it is passed solely down the female line (with apparently few exceptions). And we now know quite a number of cases where a population of one species has the mitochondrial DNA of a different, related species.
Here is a nice example. The common deer species of the eastern United States is the white-tailed deer. In the west, it is replaced by the mule deer, and in the middle they live side-by-side in the same habitats. On a large ranch in West Texas, there are herds of both species, and they have the same mitochondrial DNA! There has been some dispute in the past over whose mitochondrial DNA it actually is, but it now appears that it is that of the mule deer. We imagine that, at some time in the past, some white-tailed bucks, unable to find does of their own species, ‘made the best of a bad job’ and drove off some mule deer bucks and mated with mule deer does. Hybrids were born, and in the next generation more white-tail bucks came over and mated with them. The hybrids are now three-quarters white-tail, and one-quarter mule deer, but of course they still had the mitochondrial DNA of their mule deer grandmothers. In a few more generations, they would come to totally resemble white-tailed deer, the only legacy of their original maternal heritage being their mitochondrial DNA.
An intended pun from James Balog in another classic TED talk. If you thought climate change was merely a prediction from mathematical models, think again. The biodiversity implications are staggering.
“We have a problem of perception… Not enough people really get it yet.” J. Balog
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A good friend and colleague of mine, Dr. Clive McMahon, is visiting Adelaide for the next few weeks from Darwin. We’re attacking a few overdue manuscripts and sampling a few of Adelaide’s better drops of value-added grape juice, so I asked him to do a guest post on ConservationBytes.com about his work. So here it is, something perhaps even few Australians know much about, let alone overseas folks. If you can recall that very strange scene in the film Crocodile Dundee where the old croc hunter casts a gestured spell over a horned beast, then you’ll probably appreciate this post.
Yes, there are plenty of them in northern Australia
Invasive and feral species can be important drivers of biodiversity loss. Australia, like many other isolated islands has developed an ancient, unique and diverse ecosystem. This unique ecosystem has been under extreme pressure ever since humans arrived around 40000-60000 years ago. One of the more damaging and economically important introduced species in Australia is the Asian swamp buffalo (Bubalus bubalis). Ironically, swamp buffalo are listed as Endangered by the IUCN, and current estimates suggest that there are probably less than 4000 in their native habitats in Asia.
© B. Salau, Kakadu National Park
The first 16 buffalo were introduced to Australia in 1826 on Melville Island, and then to the mainland at Cobourg Peninsula a year later from Kupang (now West Timor, Indonesia). Another 18 buffalo were obtained from Kisar Island (northeast of modern Timor-Leste) and introduced to the Cobourg. In 1843, another 49 were introduced. When the first Cobourg settlement was abandoned in 1849, all the buffalo were released, and the population spread rapidly throughout the Northern Territory. Over the next 65 years, numbers and distribution increased to an estimated 350000 in the 1960s and 1970s and densities exceeded 25 km-2 in ‘prime’ habitat. However, the population was severely reduced during the 1980s and 1990s in parts of its range under the Brucellosis-Tuberculosis Eradication Campaign (BTEC). Although largely successful in eradicating buffalo from pastoral lands in the short term, there was no ongoing broad-scale management of numbers and the present-day population of free-ranging buffalo has recovered to former densities in some areas.
© C. Speed
Buffalo were then and still are major problem in Australia due mainly to the environmental damage they cause, such as saltwater intrusion of wetlands and trampling of sensitive habitats, their potential threat to Australia’s livestock industry as hosts for disease, and the danger they pose to human safety. Given these ecological, economic and social impacts, there is an urgent need to manage buffalo numbers.
An important step to inform management of introduced and invasive species is to determine the history of introduction and quantify the rate of spread from introduction sites. Contemporary genetic techniques in conjunction with demographic and life history information are useful tools for understanding the dynamics, population structure, biology and colonisation dynamics of plants and animals, including invasive species such as buffalo.
We are currently in the final stages of providing the first detailed analysis of the buffalo population structure (demographic and genetic) to (1) establish the rate and most probable history of spread using detailed genetic information sampled from 8 sub-populations, (2) quantify the genetic distance and mixing rates between populations and (3) describe the age structure and therefore the demographic performance of this very successful invasive species.
Firstly to get an idea of genetic structure and relatedness, we collected a total of 430 small skin biopsies from buffalo across the Northern Territory, representing eight geographically distinct populations. To determine what has made the buffalo such a successful invader it is important to know the survival and breeding performance; we also constructed seven life tables based on culled samples at different densities and in different environments to work out what are the critical components of the population – i.e., where management intervention would be most successful.
As expected from a bottlenecked population, genetic variation is low compared to the that found in swamp buffalo from India and South East Asia. Despite this reduced genetic variation, the Australian population has thrived and spread outwards from introduction sites and into culled sites at high rates over the last 160 years (covering ~ 224 000 km2 in that time).
Although buffalo in Australia experienced two major periods of population reduction since their introduction, a small proportion (estimated at ~ 20 %) escaped the BTEC reduction in the eastern part of its north Australian range. BTEC did not operate with uniformity across the entire range of buffalo, concentrating its destocking efforts in a general area from the western coast of the Northern Territory to west of the Mann River in Arnhem Land, and south roughly to Kakadu National Park’s southern border. Coincidently and not surprisingly, it is in this area that we observe most migration activity.
The subpopulation structure detected here suggests that each population, while connected over generational time scales, generally remains in its immediate vicinity over the course of management-tractable periods. Therefore, management aimed at protecting Australia’s lucrative livestock industry trading under Australia’s disease-free status will benefit directly from this knowledge. For example, the localised introduction and subsequent rapid detection of disease could be efficiently managed from local culls because short-term movements of long-distance are less likely. Our results showcase how management of animals for disease control can be effectively informed via genetic studies and so avoid the need for expensive broad-scale intervention.
Our analyses of the age structure of buffalo reveals that buffalo have the capacity to recover swiftly after control because of high survival and fertility rates. Survival in the juvenile age classes was consistently the most important modifier of population growth. In populations where juvenile animals are harvested annually, fertility determined rebound potential. Thus, management aimed at long-term control of densities should focus primarily on the sustained culling of adult females and their offspring.
Given that numbers of buffalo are increasing and that buffalo are extremely well-adapted to the monsoonal tropics (unlike cattle, buffalo can maintain body condition and positive growth during times of food shortages), they are vulnerable to extended periods of harsh conditions. Climate change predictions herald increasing rainfall in the region, thereby potentially reducing the pressure on juvenile survival. As such, buffalo population growth could conceivably increase, making future management much more difficult. In essence, we need a large, evidence-based density reduction programme in place soon to prevent the worst ecological damage to Australia’s sensitive and unique ecosystems.
Check back here for announcements of upcoming publications arising from our work.
© F. O'Connor
This ‘In Depth‘ Science Opinion piece from the ABC couldn’t have come at a better time. Written by Ian Gordon of the CSIRO, this opinion piece was written off the back of the special session on mammalian extinctions held at the recent International Congress of Ecology in Brisbane. Three previous ConservationBytes.com blogs in August (here, here and here) were devoted to specific talks at the Congress, including one about John Woinarksi’s gloomy tale of dwindling mammal populations in the Top End (which is especially frightening considering its also going on in our so-called ‘protected’ areas such as Kakadu, Litchfield and Garig Gunak Barlu National Parks!).
So, I recommend you have a read of my blog post on the shocking continued loss of Australian mammals, then read Ian’s piece copied below. Bottom lines – stop burning the shit out of our forests and encourage dingo population recovery and expansion.
Australia leads the world in mammal extinctions.
Over the last two hundred years 22 mammal species have become extinct, and over 100 are now on the threatened and endangered species list, compiled as part of the federal government’s Environment Protection and Biodiversity Conservation Act.
Evidence suggests Australia is on the cusp of another wave of mammal extinctions with a reduction in the abundance of some species and alarmingly, their range.
This is undoubtedly one of the major biodiversity conservation issues affecting Australia. It’s crucial we focus on the management solutions required to stop these species falling into extinction.
A South American success story
Working as a zoologist has allowed me to be involved in projects across the globe, looking at species at risk of extinction due to over-exploitation by humans.
Earlier this year I edited a book on the South American vicuña‘s comeback from the brink of extinction. Once abundant in the Andes, this wild relative of the llama suffered a sharp population drop in the 1960s due to international demand for its fleece.
An international moratorium on the sale of vicuña fleece in 1969 saw populations recover enough by 1987 for Andean communities to be able to harvest the fibre in a sustainable way. Population numbers of vicuña have remained healthy ever since, making it one of the few success stories of wildlife conservation worldwide.
Australia’s mammal extinction crisis
However Australia’s medium-sized mammals have had to deal with a different range of issues to the vicuña: the introduction of feral animals, particularly cats and foxes; increased grazing pressure; altered fire regimes; the clearing of habitat for development and production; and now, the effects of climate change.
It isn’t that any of these pressures are particularly important by themselves, but the fact that many of them act in concert has had a significant impact on causing the crashes in population numbers, and increasing the risk of species becoming extinct.
For example, the crescent nailtail wallaby was once an abundant and widespread macropod of central and western Australia. The pressures of feral cats and foxes coupled with clearing for agriculture and grazing, and altered fire regimes pushed this little species over the edge and it is now classified as extinct.
The problem is also more far-reaching than we first assumed. Many people may think that animals are becoming extinct in the south of Australia where habitat destruction is quite evident.
But the populations of iconic species in the north of Australia such as the northern quoll, golden bandicoot and the Carpentarian rock-rat are also collapsing. In our lifetime populations of some species have greatly reduced in number, and others have completely disappeared in landscapes that are considered to be in excellent condition.
The golden bandicoot, listed as a vulnerable species, used to be found across much of the north of Australia. It is now only found in very small populations in the Northern Territory and on the isolated Burrow Island off the coast of Western Australia.
Time to bring back the dingo?
Further research on the impacts of fire, grazing, invasive species and climate change on Australian mammals would be extremely valuable, but ecologists recognise that crucial management decisions need to be made now.
We’ve found ourselves in a position where we have identified the threats to Australian mammal species and documented the loss of these species, the role of science must turn more directly to identifying the opportunities for assisting the survival of these mammals.
In August I chaired a panel with Professor Chris Johnson from James Cook University at the International Congress of Ecology, to discuss what management could be put in place now to help beleaguered populations of small mammals recover.
Johnson’s main focus is to bring back the top-order predator.
He believes there is now good evidence that a stable population of dingoes suppresses the numbers and activity of foxes and cats, and some other feral animal species as well.
He argues that the effect of using a top predator like the dingo to hold down populations of foxes and cats is that the total intensity of predation on smaller native mammals can be reduced.
Bringing back the dingo has many sheep and cattle farmers raising their eyebrows because the wild dogs are known to kill stock. But guardian sheepdogs can protect stock herds by fighting off dingoes if they come too close. This still allows the dingoes to have a beneficial effect in the ecosystem.
Current trials of Maremma dogs, a type of sheepdog, at Dunluce sheep station in northwest Queensland demonstrate that they can be effective dingo deterrents in a pastoral zone.
This is just one potential solution that may work in some areas. Reinstating mosaic fire regimes, where patches of land are burnt at different times to allow the land to recover in stages, and controlling grazing around sensitive habitat of endangered mammals are other potential solutions that are currently under trial in various parts of the country.
Working together
Even though science doesn’t have all the answers I believe that it is more important than ever for land managers and scientists to work together to put new management regimes on the ground.
Our scientific knowledge can provide guidelines for land managers to reduce the pressures on our biodiversity. Through monitoring how species and ecosystems respond to on-ground management we can then learn and adapt our advice to meet future challenges facing Australia’s threatened species.
We need to act now: the international community is watching Australia and we have an opportunity to show how we can apply science through collaborative agreements with land managers to reduce the threats and protect endangered species.
We’ll then be able to add Australian animals to the short list of species, like the vicuña, that have been brought back from the brink of extinction.
Wildfires transform forests into mosaics of vegetation. What, where, and which plants thrive depends on when and how severely a fire affects different areas of a forest. Such heterogeneity in the landscape is essential for animal species that benefit from fire like woodpeckers. Anyone raised in rural areas will have vivid recollections of wildfires: the…
From time to time I turn my research hand to issues of invasive species control, for example, from manipulating pathogens to control rabbits, to island eradication of feral cats and pigs, to effective means to control feral deer. Not only do invasive species cost well over $1.7 trillion (yes, that’s trillion, with 12 zeros) each…
We’ve just published a paper in PLOS ONE showing high infant mortality rates are contributing to an incessant rise of the global human population, which supports arguments for greater access to contraception and family planning in low- and middle-income nations. In collaboration with Melinda Judge, Chitra Saraswati, Claire Perry, Jane Heyworth, and Peter Le Souëf…
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