In keeping with a certain whinge of mine over the last week (see Greenwash, blackwash: two faces of conservation evil), here’s a brilliant pictorial comment from Pile Higher and Deeper on the way reporters try to sex up (i.e., sensationalise) science results. Is it really necessary to dumb it down to such an extent? Surely there must be a few punters that could do without the ooohs! and aaaahs! (or am I just being naïvely hopeful?).
© J. Cham
Beware false prophets, and especially those masquerading as conservationists (or at least ‘green’) when they are not, in fact, doing anything for conservation at all. But this blog site isn’t about typical greenie evil-corporation-making-a-mess-of-the-Earth sermons (there are plenty of those); it’s instead about real conservation science that has/should/could have a real biodiversity benefits. This is why I highlight the bitey and the toothless together.
With the slow (painfully, inadequately, insufficiently slow) maturation of environmental awareness and the rising plight of biodiversity in general (including our own health and prosperity), it has become almost chic to embrace a so-called ‘green’ perspective. This approach has blown out into a full-scale business model where in many wealthier nations especially, it’s just plain good business to attract the green-conscious consumer to buy more ‘environmentally friendly’ products. Problem is, so many of these products are the farthest thing from green you can imagine (see examples here, here & here). This stimulated the environmentalist Jay Westerveld to coin the term greenwashing in 1986. Greenwashing is basically defined as activities that misleadingly give the impression of environmentally sound management that thereby deflect attention away from the continued pursuit of environmentally destructive activities.
Well, not that the problem has disappeared, or even dissipated (if anything, it’s growing), but I don’t want to focus on that here. Instead, I want to highlight a recent paper in which I was involved that outlines too how environmental groups can be guilty of almost the same sin – claiming businesses, practices, individuals, corporations, etc. are far more environmentally destructive than they really are. This, we termed blackwashing.
The paper by Koh and colleagues entitled Wash and spin cycle threats to tropical biodiversity just came out online in the journal Biotropica, and therein we describe the greenwashing-blackwashing twin conservation evils using the oil palm controversy as an excellent example case. Just in case you didn’t know, much of the tropical world (especially South East Asia) is undergoing massive conversion of native forests to oil palm plantations, to the overwhelming detriment of biodiversity. I’ve covered the issue in several posts on ConservationBytes.com before (see for example Tropical forests worth more standing, Indonesia’s precious peatlands under oil palm fire & More greenwashing from the Malaysian oil palm industry).
Briefly, we demonstrate how the palm oil industry is guilty of the following greenwashes:
On the either side, various environmental groups such as Greenpeace, have promoted the following blackwashes:
For details, see the paper online.
Now, I’d probably tend to believe some of the less outrageous claims made by some environmental groups because if anything, the state of biodiversity is probably overall worse than what most people realise. However, when environmental groups are exposed for exaggerations, or worse, lies, then their credibility goes out the window and even those essentially promoting their cause (e.g., conservation biologists like myself) will have nothing to do with them. The quasi-religious zealotry of anti-whaling campaigns is an example of a terrible waste of funds, goodwill and conservation resources that could be otherwise spent on real conservation gains. Instead, political stunts simply alienate people who would otherwise reasonably contribute to improving the state of biodiversity. Incidentally, an environmental advocacy group in Australia emailed me to support their campaign to highlight the plight of sharks. I am a firm supporter of better conservation of sharks (see recent paper and post about this here). However, when I read their campaign propaganda, the first sentence read:
I immediately distanced myself from them. This is a blatant lie and terrible over-exaggeration. Ninety per cent of sharks HAVE NOT been wiped out. Some localised depletions have occurred, and not one single shark species has been recorded going extinct since records began. While I agree the world has a serious shark problem, saying outrageous things like this will only serve to weaken your cause. My advice to any green group is to get your facts straight and avoid the sensationlist game – you won’t win it, and you probably won’t be successful in doing anything beneficial for the species you purport to save.
CJA Bradshaw
Koh, L., Ghazoul, J., Butler, R., Laurance, W., Sodhi, N., Mateo-Vega, J., & Bradshaw, C. (2009). Wash and Spin Cycle Threats to Tropical Biodiversity Biotropica DOI: 10.1111/j.1744-7429.2009.00588.x
We do a lot in our lab to get our research results out to a wider community than just scientists – this blog is just one example of how we do that. But of course, we rely on the regular media (television, newspaper, radio) heavily to pick up our media releases (see a list here). I firmly believe it goes well beyond shameless self promotion – it’s a duty of every scientist I think to tell the world (i.e., more than just our colleagues) about what we’re being paid to do. And the masses are hungry for it.
However, the demise of the true ‘journalist’ (one who investigates a story – i.e., does ‘research’) in favour of the automaton ‘reporter’ (one who merely regurgitates, and then sensationalises, what he/she is told or reads) worldwide (and oh, how we are plagued with reporters and deeply in need of journalists in Australia!) means that there is some horrendous stories out there, especially on scientific issues. This is mainly because most reporters have neither the training nor capacity to understand what they’re writing about.
This issue is also particular poignant for the state of the environment, climate change and biodiversity loss – I’ve blogged about this before (see Poor media coverage promotes environmental apathy and untruths).
But after a 30-minute telephone interview with a very friendly American food journalist yesterday, I expected a reasonable report on the issue of frog consumption because, well, I explained many things to her as best I could. What was eventually published was appalling.
Now, in all fairness, I think she was trying to do well, but it’s as though she didn’t even listen to me. The warning bells should have rung loudly when she admitted she hadn’t read my blog “in detail” (i.e., not at all?). You can read the full article here, but let me just point out some of the inconsistencies:
Ah, no. I told her that between 30 and 50 % of frogs could be threatened with extinction (~30 % officially from the IUCN Red List). It could be as much as half given the paucity of information on so many species. A great example of reporter cherry-picking to add sensationalism.
Again, no, I didn’t. I clearly told her that the number one, way-out-in-front cause of frog declines worldwide is habitat loss. I mentioned chytrid fungus as another major contributor, and that climate change exacerbates the lot. Harvesting pressure is a big unknown in terms of relative impact, but I suspect it’s large.
Hmmm. One man? I had a great team of colleagues co-write the original paper in Conservation Biology. I wasn’t even the lead author! Funny how suddenly I’m a lone wolf on a ‘campaign’. Bloody hell.
“Aghast”, was I? I don’t recall being particularly emotional when I told her that I found a photo of Barack Obama eating frog legs during his election campaign. I merely pointed this out to show that the product is readily available in the USA. I also mentioned absolutely nothing about whales or their loins.
So, enough of my little humorous whinge. My point is really that there are plenty of bad journalists out there with little interest in reporting the truth on environmental issues (tell us something we don’t know, Bradshaw). If you want to read a good story about the frog consumption issue, check out a real journalist’s perspective here.
I know I’ve blogged recently about this, but The Adelaidean did a nice little article that I thought I’d reproduce here. The source can be found here.
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© R. Harcourt
Quite some time ago my colleague and (now former) postdoctoral fellow, Iain Field, and I sat down to examine in gory detail the extent of the threat to global populations of sharks, rays and chimaeras (chondrichthyans). I don’t think we quite realised the mammoth task we had set ourselves. Several years and nearly a hundred pages later, we have finally achieved our goal.
Introducing the new paper in Advances in Marine Biology entitled Susceptibility of sharks, rays and chimaeras to global extinction by Iain Field, Mark Meekan, Rik Buckworth and Corey Bradshaw.
The paper covers the following topics:
- Niche breadth
- Age and growth
- Reproduction and survival
- Fishing
- Beach meshing
- Habitat loss
- Pollution and non-indigenous species
- Drivers of threat risk in chondrichthyans and teleosts
- Global distribution of threatened chondrichthyan taxa
- Ecological, life history and human-relationship attributes
- Threat risk analysis
- Relative threat risk of chondrichthyans and teleosts
- Ecosystem roles of predators
- Predator loss in the marine realm
- Ecosystem roles of chondrichthyans
- Role of fisheries in future chondrichthyan extinctions
- Climate change
- Extinction synergies
- Research needs
As mentioned, quite a long analysis of the state of sharks worldwide. Bottom line? Well, as most of you might already know sharks aren’t doing too well worldwide, with around 52 % listed on the IUCN’s Red List of Threatened Species. This compares interestingly to bony fishes (teleosts) that, although having only 8 % of all species Red-Listed, are generally in higher-threat Red List categories. We found that body size (positively) and geographic range (negatively) correlated with threat risk in both groups, but Red-Listed bony fishes were still more likely to be categorised as threatened after controlling for these effects.
In some ways this sort of goes against the notion that sharks are inherently more extinction-prone than other fish – a common motherhood statement seen at the beginning of almost all papers dealing with shark threats. What it does say though is that because sharks are on average larger and less fecund than your average fish, they tend to bounce back from declines more slowly, so they are more susceptible to rapid environmental change than your average fish. Guess what? We’re changing the environment pretty rapidly.
We also determined the spatial distribution of threat, and found that Red-Listed species are clustered mainly in (1) south-eastern South America; (2) western Europe and the Mediterranean; (3) western Africa; (4) South China Sea and South East Asia and (5) south-eastern Australia.
© W. White
Now, what are the implications for the loss of these species? As I’ve blogged recently, the reduction in predators in general can be a bad thing for ecosystems, and sharks are probably some of the best examples of ecosystem structural engineers we know (i.e., eating herbivores; ‘controlling’ prey densities, etc.). So, we should be worried when sharks start to disappear. One thing we also discovered is that we still have a rudimentary understanding of how climate change will affect sharks, the ways in which they structure ecosystems, and how they respond to coastal development. Suffice it to say though that generally speaking, things are not rosy if you’re a shark.
We end off with a recommendation we’ve been promoting elsewhere – we should be managing populations using the minimum viable population (MVP) size concept. Making sure that there are a lot of large, well-connected populations around will be the best insurance against extinction.
I.C. Field, M.G. Meekan, R.C. Buckworth, & C.J.A. Bradshaw (2009). Susceptibility of Sharks, Rays and Chimaeras to Global Extinction Advances in Marine Biology, 56, 275-363 : 10.1016/S0065-2881(09)56004-X
Here’s a little story for you about how a casual chat over a glass of wine (or many) can lead to great scientific endeavours.
A few years ago I was sitting in the living room of my good friends Noel Preece and Penny van Oosterzee in Darwin chatting about life, the universe, and everything. They rather casually mentioned that they would be selling their environmental consulting company and their house and moving to the Queensland rain forest. Ok – sounded like a pretty hippy thing to do when you’re thinking about ‘retiring’ (only from the normal grindstone, at least). But it wasn’t about the easy life away from it all (ok, partially, perhaps) – they wanted to do something with their reasonably large (181 ha), partially deforested (51-ha paddock) property investment. By ‘something’, I mean science.
So they asked me – how would we go about getting money to investigate the best way to reforest a tropical rain forest? I had no idea. As it turns out, no one really knows how to restore rain forests properly. Sure, planting trees happens a lot, but the random, willy-nilly, unquantified ways in which it is done means that no one can tell you what the biggest biodiversity bang for your buck is, or even if it can compete on the carbon sequestration front.
Why carbon sequestration? Well, in case you’ve had your head up your bum for the last decade, one of the major carbon mitigating schemes going is the offset idea – for every tonne of carbon you emit as a consumer, you (or more commonly, someone else you pay) plant a certain number of trees (because trees need carbon to grow and so suck it out of the atmosphere). Nice idea, but if you deforest native ecosystems just to bash up quick-growing monoculture plantations of (usually) exotic species with little benefit to native biota, biodiversity continues to spiral down the extinction vortex. So, there has to be a happy medium, and there has to be a way to measure it.
So I said to Penny and Noel “Why don’t we bash together a proposal and get some experts in the field involved and submit it to the Australian Research Council (ARC) for funding?” They thought that was a smashing idea, and so we did.
Fast forward a few years and … success! The Thiaki Project was born (‘Thiaki’ is the name of the Creek flowing through the property north of Atherton – seems to be of Greek origin). We were extremely lucky to find a new recruit to the University of Queensland, Dr. Margie Mayfield (who worked previously with Paul Ehrlich), who was not only an expert in the area of tropical reforestation for biodiversity, she also had the time and energy to lead the project. We garnered several other academic and industry partners and came up with a pretty sexy experiment that is just now getting underway thanks to good old Mr. ARC.
The project is fairly ambitious, even though the experiments per se are fairly straight forward. We’re using a randomised block design where we are testing 3 tree diversity treatments (monoculture, 1 species each from 6 families, and 5 species each from those same 6 families) and two planting densities (high and low). The major objective is to see what combination of planting density and native tree species provides the most habitat for the most species. We’re starting small, looking mainly at various insects as they start to use the newly planted blocks, but might expand the assessments (before planting and after) to reptiles, amphibians and possibly birds later on.
But we’re not stopping there – we were fortunate enough to get get a clever soil scientist, Dr. David Chittleborough of the University of Adelaide, involved so we could map the change in soil carbon during the experiment. Our major challenge is to find the right combination of tree species and planting techniques that restore native biodiversity the most effectively, all the while maximising carbon sequestration from the growing forest. And of course, we’re trying to do this as most cost-effectively as we can – measuring the relative costs will give landowners contemplating reforestation the scale of expenditures expected.
I’m pretty proud of what Margie, Noel, Penny and the rest of the team have accomplished so far, and what’s planned. Certainly the really exciting results are years away yet, but stay tuned – Thiaki could become the model for tropical reforestation worldwide. Follow the Thiaki Project website for regular updates.
I’d also love to recreate the Thiaki Project in southern Australia because as it turns out, no one knows how to maximise biodiversity and carbon sequestration for the lowest cost in temperate reforestation projects either. All we need is a few hundred hectares of deforested land (shouldn’t be hard to find), about $1 million to start, and a bit of time. Any takers?
© C. Madden
© ABC 2009
Yesterday I was asked to do a quick interview on ABC television (Midday Report) about the release of the 2009 IUCN Red List of Threatened Species. I’ve blogged about the importance of the Red List before, but believe we have a lot more to do with species assessments and getting prioritisation right with respect to minimum viable population size. Have a listen to the interview itself, and read the IUCN’s media release reproduced below.
My basic stance is that we’ve only just started to assess the number of species on the planet (under 50000), yet there are many millions of species still largely under-studied and/or under-described (e.g., extant species richness = > 4 million protists, 16600 protozoa, 75000-300000 helminth parasites, 1.5 million fungi, 320000 plants, 4-6 million arthropods, > 6500 amphibians, 10000 birds and > 5000 mammals – see Bradshaw & Brook 2009 J Cosmol for references). What we’re looking at here is a refinement of knowledge (albeit a small one). We are indeed in the midst of the Anthropocene mass extinction event – there is nothing ‘looming’ about it. We are essentially losing species faster than we can assess them. I believe it’s important to make this clearer to those not working directly in the field of biodiversity conservation.
Extinction crisis continues apace – IUCN
Gland, Switzerland, 3 November, 2009 (IUCN) – The latest update of the IUCN Red List of Threatened Species™ shows that 17,291 species out of the 47,677 assessed species are threatened with extinction.
The results reveal 21 percent of all known mammals, 30 percent of all known amphibians, 12 percent of all known birds, and 28 percent of reptiles, 37 percent of freshwater fishes, 70 percent of plants, 35 percent of invertebrates assessed so far are under threat.
“The scientific evidence of a serious extinction crisis is mounting,” says Jane Smart, Director of IUCN’s Biodiversity Conservation Group. “January sees the launch of the International Year of Biodiversity. The latest analysis of the IUCN Red List shows the 2010 target to reduce biodiversity loss will not be met. It’s time for governments to start getting serious about saving species and make sure it’s high on their agendas for next year, as we’re rapidly running out of time.”
Of the world’s 5,490 mammals, 79 are Extinct or Extinct in the Wild, with 188 Critically Endangered, 449 Endangered and 505 Vulnerable. The Eastern Voalavo (Voalavo antsahabensis) appears on the IUCN Red List for the first time in the Endangered category. This rodent, endemic to Madagascar, is confined to montane tropical forest and is under threat from slash-and-burn farming.
There are now 1,677 reptiles on the IUCN Red List, with 293 added this year. In total, 469 are threatened with extinction and 22 are already Extinct or Extinct in the Wild. The 165 endemic Philippine species new to the IUCN Red List include the Panay Monitor Lizard (Varanus mabitang), which is Endangered. This highly-specialized monitor lizard is threatened by habitat loss due to agriculture and logging and is hunted by humans for food. The Sail-fin Water Lizard (Hydrosaurus pustulatus) enters in the Vulnerable category and is also threatened by habitat loss. Hatchlings are heavily collected both for the pet trade and for local consumption.
“The world’s reptiles are undoubtedly suffering, but the picture may be much worse than it currently looks,” says Simon Stuart, Chair of IUCN’s Species Survival Commission. “We need an assessment of all reptiles to understand the severity of the situation but we don’t have the $2-3 million to carry it out.”
The IUCN Red List shows that 1,895 of the planet’s 6,285 amphibians are in danger of extinction, making them the most threatened group of species known to date. Of these, 39 are already Extinct or Extinct in the Wild, 484 are Critically Endangered, 754 are Endangered and 657 are Vulnerable.
The Kihansi Spray Toad (Nectophrynoides asperginis) has moved from Critically Endangered to Extinct in the Wild. The species was only known from the Kihansi Falls in Tanzania, where it was formerly abundant with a population of at least 17,000. Its decline is due to the construction of a dam upstream of the Kihansi Falls that removed 90 percent of the original water flow to the gorge. The fungal disease chytridiomycosis was probably responsible for the toad’s final population crash.
The fungus also affected the Rabb’s Fringe-limbed Treefrog (Ecnomiohyla rabborum), which enters the Red List as Critically Endangered. It is known only from central Panama. In 2006, the chytrid fungus (Batrachochytrium dendrobatidis) was reported in its habitat and only a single male has been heard calling since. This species has been collected for captive breeding efforts but all attempts have so far failed.
Of the 12,151 plants on the IUCN Red List, 8,500 are threatened with extinction, with 114 already Extinct or Extinct in the Wild. The Queen of the Andes (Puya raimondii) has been reassessed and remains in the Endangered category. Found in the Andes of Peru and Bolivia, it only produces seeds once in 80 years before dying. Climate change may already be impairing its ability to flower and cattle roam freely among many colonies, trampling or eating young plants.
There are now 7,615 invertebrates on the IUCN Red List this year, 2,639 of which are threatened with extinction. Scientists added 1,360 dragonflies and damselflies, bringing the total to 1,989, of which 261 are threatened. The Giant Jewel (Chlorocypha centripunctata), classed as Vulnerable, is found in southeast Nigeria and southwest Cameroon and is threatened by forest destruction.
Scientists also added 94 molluscs, bringing the total number assessed to 2,306, of which 1,036 are threatened. Seven freshwater snails from Lake Dianchi in Yunnan Province, China, are new to the IUCN Red List and all are threatened. These join 13 freshwater fishes from the same area, 12 of which are threatened. The main threats are pollution, introduced fish species and overharvesting.
There are now 3,120 freshwater fishes on the IUCN Red List, up 510 species from last year. Although there is still a long way to go before the status all the world’s freshwater fishes is known, 1,147 of those assessed so far are threatened with extinction. The Brown Mudfish (Neochanna apoda), found only in New Zealand, has been moved from Near Threatened to Vulnerable as it has disappeared from many areas in its range. Approximately 85-90 percent of New Zealand’s wetlands have been lost or degraded through drainage schemes, irrigation and land development.
“Creatures living in freshwater have long been neglected. This year we have again added a large number of them to the IUCN Red List and are confirming the high levels of threat to many freshwater animals and plants. This reflects the state of our precious water resources. There is now an urgency to pursue our effort but most importantly to start using this information to move towards a wise use of water resources,” says Jean-Christophe Vié, Deputy Head of the IUCN Species Programme.
“This year’s IUCN Red List makes for sobering reading,” says Craig Hilton-Taylor, Manager of the IUCN Red List Unit. “These results are just the tip of the iceberg. We have only managed to assess 47,663 species so far; there are many more millions out there which could be under serious threat. We do, however, know from experience that conservation action works so let’s not wait until it’s too late and start saving our species now.”
The status of the Australian Grayling (Prototroctes maraena), a freshwater fish, has improved as a result of conservation efforts. Now classed as Near Threatened as opposed to Vulnerable, the population has recovered thanks to fish ladders which have been constructed over dams to allow migration, enhanced riverside vegetation and the education of fishermen, who now face heavy penalties if found with this species.
A quick post to talk about a subject I’m more and more interested in – the direct link between environmental degradation (including biodiversity loss) and human health.
To many conservationists, people are the problem, and so they focus naturally on trying to maintain biodiversity in spite of human development and spread. Well, it’s 60+ years since we’ve been doing ‘conservation biology’ and biodiversity hasn’t been this badly off since the Cretaceous mass extinction event 146-64 million years ago. We now sit squarely within the geological era more and more commonly known as the ‘Anthropocene’, so if we don’t consider people as an integral part of any ecosystem, then we are guaranteed to fail biodiversity.
I haven’t posted in a week because I was in Shanghai attending the rather clumsily entitled “Thematic Reference Group (TRG) on Environment, Agriculture and Infectious Disease’, which is a part of the UNICEF/UNDP/World Bank/World Health Organization Special Programme for Research and Training in Tropical Diseases (TDR) (what a mouthful that is). What’s this all about and why is a conservation ecologist (i.e., me) taking part in the group?
It’s taken humanity a while to realise that what we do to the planet, we eventually end up doing to ourselves. The concept of ecosystem services1 demonstrates this rather well – our food, weather, wealth and well-being are all derived from healthy, functioning ecosystems. When we start to bugger up the inter-species relationships that define one element of an ecosystem, then we hurt ourselves. I’ve blogged about this topic a few times before with respect to flooding, pollination, disease emergence and carbon sequestration.
Our specific task though on the TRG is to define the links between environmental degradation, agriculture, poverty and infectious disease in humans. Turns out, there are quite a few examples of how we’re rapidly making ourselves more susceptible to killer infectious diseases simply by our modification of the landscape and seascape.
Some examples are required to illustrate the point. Schistosomiasis is a snail-borne fluke that infects millions worldwide, and it is on the rise again from expanding habitat of its host due to poor agricultural practices, bad hygiene, damming of large river systems and climate warming. Malaria too is on the rise, with greater and greater risk in the endemic areas of its mosquito hosts. Chagas (a triatomine bug-borne trypanosome) is also increasing in extent and risk. Some work I’m currently doing under the auspices of the TRG is also showing some rather frightening correlations between the degree of environmental degradation within a country and the incidence of infectious disease (e.g., HIV, malaria, TB), non-infectious disease (e.g., cancer, cardiovascular disease) and indices of life expectancy and child mortality.
I won’t bore you with more details of the group because we are still drafting a major World Health Organization report on the issues and research priorities. Suffice it to say that if we want to convince policy makers that resilient functioning ecosystems with healthy biodiversity are worth saving, we have to show them the link to infectious disease in humans, and how this perpetuates poverty, rights injustices, gender imbalances and ultimately, major conflicts. An absolute pragmatist would say that the value of keeping ecosystems intact for this reason alone makes good economic sense (treating disease is expensive, to say the least). A humanitarian would argue that saving human lives by keeping our ecosystems intact is a moral obligation. As a conservation biologist, I argue that biodiversity, human well-being and economies will all benefit if we get this right. But of course, we have a lot of work to do.
1Although Bruce Wilcox (another of the TRG expert members), who I will be highlighting soon as a Conservation Scholar, challenges the notion of ecosystem services as a tradeable commodity and ‘service’ as defined. More on that topic soon.
I love these sorts of experiments. Ecology (and considering conservation ecology a special subset of the larger discipline) is a messy business, mainly because ecosystems are complex, non-linear, emergent, interactive, stochastic and meta-stable entities that are just plain difficult to manipulate experimentally. Therefore, making inference of complex ecological processes tends to be enhanced when the simplest components are isolated.
Enter the ‘mini-ecosystem-in-a-box’ approach to ecological research. I’ve blogged before about some clever experiments to examine the role of connectivity among populations in mitigating (or failing to mitigate) extinction risk, and alluded to others indicating how harvest reserves work to maximise population persistence. This latest microcosm experiment is another little gem and has huge implications for conservation.
A fairly long-standing controversy in conservation biology, and in invasive species biology in particular, is whether intact ecosystems are in any way more ‘resilient’ to invasion by alien species (the latter most often being deliberately or inadvertently introduced by humans – think of Australia’s appalling feral species problems; e.g., buffalo, foxes and cats, weeds). Many believe by default that more ‘pristine’ (i.e., less disturbed by humans) communities will naturally provide more ecological checks against invasives because there are more competitors, more specialists and more predators. However, considering the ubiquity of invasives around the world, this assumption has been challenged vehemently.
The paper I’m highlighting today uses the microcosm experimental approach to show how native predators, when abundant, can reduce the severity of an invasion. Using a system of two mosquito species (one ‘native’ – what’s ‘native’ in a microcosm? [another subject] – and one ‘invasive’) and a native midge predator, Juliano and colleagues demonstrate in their paper Your worst enemy could be your best friend: predator contributions to invasion resistance and persistence of natives that predators are something you want to keep around.
In short, they found little evidence of direct competition between the two mosquitoes in terms of abundance when placed together without predators, but when the midges were added, the persistence of the invasive mosquito was reduced substantially. Of course, the midge predators did do their share of damage on the native mosquitoes in terms of reducing the latter’s abundance, but through a type of competitive release from their invasive counterparts, the midges’ reduction of the invasive species left the native mosquito free to develop faster (i.e., more per capita resources).
Such a seemingly academic result has huge conservation implications. In most systems, predators are some of the largest and slowest-reproducing species, so they are characteristically the first to feel the hammer of human damage. From bears to sharks, and tigers to wolves, big, charismatic predators are on the wane worldwide. Juliano and colleagues’ nice experimental work with insects reminds us that keeping functioning native ecosystems intact from all trophic perspectives is imperative.
Juliano, S., Lounibos, L., Nishimura, N., & Greene, K. (2009). Your worst enemy could be your best friend: predator contributions to invasion resistance and persistence of natives Oecologia DOI: 10.1007/s00442-009-1475-x
I just returned from a week-long scientific mission in China sponsored by the Australian Academy of Science, the Australian Academy of Technological Sciences and Engineering and the Chinese Academy of Sciences. I was invited to attend a special symposium on Marine and Deltaic Systems where research synergies between Australian and Chinese scientists were to be explored. The respective academies really rolled out the red carpet for the 30 or so Australian scientists on board, so I feel very honoured to have been invited.
During our marine workshop, one of my Chinese counterparts, Dongyan Liu from the Yantai Institute for Coastal Zone Research, presented a brilliant piece of ecological sleuthing that I must share with readers of ConservationBytes.com.
The first time you go to China the thing that strikes you is that everything is big – big population, big cities, big buildings, big projects, big budgets and big, big, big environmental problems. After many years of overt environmental destruction in the name of development, the Chinese government (aided by some very capable scientists) is now starting to address the sins of the past.
Liu and colleagues published their work earlier this year in Marine Pollution Bulletin in a paper entitled World’s largest macroalgal bloom caused by expansion of seaweed aquaculture in China, which describes a bloody massive outbreak of a particularly nasty ‘green tide’.
What’s a ‘green tide’? In late June 2008 in the coastal city of Qingdao not far from Beijing (and just before the 2008 Olympics), a whopping 1 million tonnes of green muck washed up along approximately 400 km2 of coastline. It took 10,000 volunteers 2 weeks to clean up the mess. At the time, many blamed the rising eutrophication of coastal China as the root cause, and a lot of people got their arse kicked over it. However, the reality was that it wasn’t so simple.
The Yellow Sea abutting this part of the Chinese coast is so named because of its relatively high productivity. Warm waters combined with good mixing mean that there are plenty of essential nutrients for green things to grow. So, adding thousands of tonnes of fertilisers from Chinese agricultural run-off seems like a logical explanation for the bloom.
Qingdao green tide 2008 © Elsevier
However, it turns out that the bulk of the green slime was comprised of a species called Enteromorpha prolifera, and it just so happens that this particularly unsavoury seaweed loves to grow on the infrastructure used for the aquaculture of nori (a.k.a. amanori or zicai) seaweed (mainly, Porphyra yezoensis). Problem is, P. yezoensis is grown mainly on the coast hundreds of kilometres to the south.
Liu and colleagues examined both satellite imagery and detailed oceanographic data from the period prior to the green tide and not only spotted green splotches many kilometres long, they also determined that the current flow and wind direction placed the trajectory of any green slime mats straight for Qingdao.
So, how does it happen? Biofouling by E. prolifera on P. yezoensis aquaculture frames is dealt with mainly by manual cleaning and then dumping the unwanted muck on the tidal flats. When the tide comes back in, it washes many thousands of kilos of this stuff back out to sea, which then accumulates in rafts and continues to grow in the warm, rich seas. Subsequent genetic work also confirmed that the muck at sea was the same stock as the stuff growing on the aquaculture frames.
Apart from some lovely sleuthing work, the implications are pretty important from a biodiversity perspective. Massive eutrophication coupled with aquaculture that inadvertently spawns a particularly nasty biofouling species is a good recipe for oxygen depletion in areas where the eventual slime monster starts to decay. This can lead to so-called ‘dead’ zones that can kill off huge numbers of marine species. So, the proper management of aquaculture in the hungry Goliath that is China becomes essential to reduce the incidence of dead zones.
Fortunately, it looks like Liu and colleagues’ work is being taken seriously by the Chinese government who is now contemplating financial support for aquaculturists to clean their infrastructure properly without dumping the sludge to sea. A simple policy shift could save a lot of species, a lot of money, and a lot of embarrassment (not to mention prevent a lot of bad smells).
Liu, D., Keesing, J., Xing, Q., & Shi, P. (2009). World’s largest macroalgal bloom caused by expansion of seaweed aquaculture in China Marine Pollution Bulletin, 58 (6), 888-895 DOI: 10.1016/j.marpolbul.2009.01.013
The second-to-last issue in 2009 (October) of Conservation Letters is now out. Click here for full access.
Household goods made of non-timber forest products. © N. Sasaki
Papers in this issue:
Cronus
Bit of a strange one for you today, but here’s a post I hope you’ll enjoy.
My colleague, Barry Brook, and I recently published a paper in the very new and perhaps controversial online journal , the Journal of Cosmology. Cosmology? According to the journal, ‘cosmology’ is:
“the study and understanding of existence in its totality, encompassing the infinite and eternal, and the origins and evolution of the cosmos, galaxies, stars, planets, earth, life, woman and man”.
The journal publishes papers dealing with ‘cosmology’ and is a vehicle for those who wish to publish on subjects devoted to the study of existence in its totality.
Ok. Quite an aim.
Our paper is part of the November (second ever) issue of the journal entitled Asteroids, Meteors, Comets, Climate and Mass Extinctions, and because we were the first to submit, we managed to secure the first paper in the issue.
Our paper, entitled The Cronus hypothesis – extinction as a necessary and dynamic balance to evolutionary diversification, introduces a new idea in the quest to find that perfect analogy for understanding the mechanisms dictating how life on our planet has waxed and waned over the billions of years since it first appeared.
Gaia
In the 1960s, James Lovelock conceived the novel idea of Gaia – that the Earth functions like a single, self-regulating organism where life itself interacts with the physical environment to maintain conditions favourable for life (Gaia was the ancient Greeks’ Earth mother goddess). Embraced, contested, denounced and recently re-invigorated, the idea has evolved substantially since it first appeared. More recently (this year, in fact), Peter Ward countered the Gaia hypothesis with his own Greek metaphor – the Medea hypothesis. Essentially this view holds that life instead ‘seeks’ to destroy itself in an anti-Gaia manner (Medea was the siblicidal wife of Jason of the Argonauts). Ward described his Medea hypothesis as “Gaia’s evil twin”.
One can marvel at the incredible diversity of life on Earth (e.g., conservatively, > 4 million protists, 16600 protozoa, 75000-300000 helminth parasites, 1.5 million fungi, 320000 plants, 4-6 million arthropods, > 6500 amphibians, 10000 birds and > 5000 mammals) and wonder that there might be something in the ‘life makes it easier for life’ idea underlying Gaia. However, when one considers that over 99 % of all species that have ever existed are today extinct, then a Medea perspective might dominate.
Medea
Enter Cronus. Here we posit a new way of looking at the tumultuous history of life and death on Earth that effectively relegates Gaia and Medea to opposite ends of a spectrum. Cronus (patricidal son of Gaia overthrown by his own son, Zeus, and banished to Hades) treats speciation and extinction as birth and death in a ‘metapopulation’ of species assemblages split into biogeographic realms. Catastrophic extinction events can be brought about via species engineering their surroundings by passively modifying the delicate balance of oxygen, carbon dioxide and methane – indeed, humans might be the next species to fall victim to our own Medean tendencies. But extinction opens up new niches that eventually elicit speciation, and under conditions of relative environmental stability, specialists evolve because they are (at least temporarily) competitive under those conditions. When conditions change again, extinction ensues because not all can adapt quickly enough. Just as all individuals born in a population must eventually die, extinction is a necessary termination.
We think the Cronus metaphor has a lot of advantages over Gaia and Medea. The notion of a community of species as a population of selfish individuals retains the Darwinian view of contestation; self-regulation in Cronus occurs naturally as a result of extinction modifying the course of future evolution. Cronus also makes existing mathematical tools developed for metapopulation theory amenable to broader lines of inquiry.
For example, species as individuals with particular ‘mortality’ (extinction) rates, and lineages with particular ‘birth’ (speciation) rates, could interact and disperse among ‘habitats’ (biogeographical realms). ‘Density’ feedback could be represented as competitive exclusion or symbioses. As species dwindle, feedbacks such as reduced community resilience that further exacerbate extinction risk (Medea-like phase), and stochastic fluctuation around a ‘carrying capacity’ (niche saturation) arising when environmental conditions are relatively stable is the Gaia-like phase. Our Cronus framework is also scale-invariant – it could be applied to microbial diversity on another organism right up to inter-planetary exchange of life (panspermia).
What’s the relevance to conservation? We’re struggling to prevent extinction, so understanding how it works is an essential first step. Without the realisation that extinction is necessary (albeit, at rates preferably slower than they are currently), we cannot properly implement conservation triage, i.e., where do we invest in conservation and why?
We had fun with this, and I hope you enjoy it too.
Bradshaw, C.J.A., & Brook, B.W. (2009). The Cronus Hypothesis – extinction as a necessary and dynamic balance to evolutionary diversification Journal of Cosmology, 2, 201-209 Other: http://journalofcosmology.com/Extinction100.html
Ah, it doesn’t go away, does it? Or at least, we won’t let it.
That concept of ‘how many is enough?’ in conservation biology, the so-called ‘minimum viable population size‘, is enough to drive some conservation practitioners batty.
How many times have we heard the (para-) phrase: “It’s simply impractical to bring populations of critically endangered species up into the thousands”?
Well, my friends, if you’re not talking thousands, you’re wasting everyone’s time and money. You are essentially managing for extinction.
Our new paper out online in Biological Conservation entitled Pragmatic population viability targets in a rapidly changing world (Traill et al.) shows that populations of endangered species are unlikely to persist in the face of global climate change and habitat loss unless they number around 5000 mature individuals or more.
After several meta-analytic, time series-based and genetic estimates of the magic minimum number all agreeing, we can be fairly certain now that if a population is much less than several thousands (median = 5000), its likelihood of persisting in the long run in the face of normal random variation is pretty small.
We conclude essentially that many conservation biologists routinely underestimate or ignore the number of animals or plants required to prevent extinction. In fact, aims to maintain tens or hundreds of individuals, when thousands are actually needed, are simply wasting precious and finite conservation resources. Thus, if it is deemed unrealistic to attain such numbers, we essentially advise that in most cases conservation triage should be invoked and the species in question be abandoned for better prospects
A long-standing idea in species restoration programs is the so-called ‘50/500’ rule; this states that at least 50 adults are required to avoid the damaging effects of inbreeding, and 500 to avoid extinctions due to the inability to evolve to cope with environmental change. Our research suggests that the 50/500 rule is at least an order of magnitude too small to stave off extinction.
This does not necessarily imply that populations smaller than 5000 are doomed. But it does highlight the challenge that small populations face in adapting to a rapidly changing world.
We are battling to prevent a mass extinction event in the face of a growing human population and its associated impact on the planet, but the bar needs to be a lot higher. However, we shouldn’t necessarily give up on critically endangered species numbering a few hundred of individuals in the wild. Acceptance that more needs to be done if we are to stop ‘managing for extinction’ should force decision makers to be more explicit about what they are aiming for, and what they are willing to trade off, when allocating conservation funds.
(with thanks to Lochran Traill, Barry Brook and Dick Frankham)
Traill, L.W., Brook, B.W., Frankham, R.R., & Bradshaw, C.J.A. (2009). Pragmatic population viability targets in a rapidly changing world Biological Conservation DOI: 10.1016/j.biocon.2009.09.001
I’m going to do a double review here of two papers currently online in Proceedings of the Royal Society B: Biological Sciences. I’m lumping them together because they both more or less challenge the pervasive conservation/restoration paradigm that connectivity is the key to reducing extinction risk. It’s just interesting (and slightly amusing) that the two were published in the same journal and at about the same time, but by two different groups.
From our own work looking at the correlates of extinction risk (measured mainly by proxy as threat risk), the range of a population (i.e., the amount of area and number of habitats it covers) is the principal determinant of risk – the smaller your range, the greater your chance of shuffling off this mortal coil (see also here). This is, of course, because a large range usually means that you have some phenotypic plasticity in your habitat requirements, you can probably disperse well, and your not going to succumb to localised ‘catastrophes’ as often. It also probably means (but not always) that your population size increases as your range size increases; as we all know, populations must be beyond their minimum viable population size to have a good chance of persisting random demographic and environmental vagaries.
Well, the two papers in question, ‘Both population size and patch quality affect local extinctions and colonizations‘ by Franzén & Nilssen and ‘Environment, but not migration rate, influences extinction risk in experimental metapopulations‘ by Griffen & Drake, show that connectivity (i.e., the probability that populations are connected via migration) are probably the least important components in the extinction-persistence game.
Using a solitary bee (Andrena hattorfiana) metapopulation in Sweden, Franzén & Nilssen show that population size and food patch quality (measured by number of pollen-producing plants) were directly (but independently) correlated with extinction risk. Bigger populations in stable, high-quality patches persisted more readily. However, connectivity between patches was uncorrelated with risk.
Griffen & Drake took quite a different approach and stacked experimental aquaria full of daphnia (Daphnia magna) on top of one another to influence the amount of light (and hence, amount of food from algal growth) to which the populations had access (it’s interesting to note here that this was unplanned in the experiment – the different algal growth rates related to the changing exposure to light was a serendipitous discovery that allowed them to test the ‘food’ hypothesis!). They also controlled the migration rate between populations by varying the size of holes connecting the aquaria. In short, they found that environmentally influenced (i.e., food-influenced) variation was far more important at dictating population size and fluctuation than migration, showing again that conditions promoting large population size and reducing temporal variability are essential for reducing extinction risk.
So what’s the upshot for conservation? Well, many depressed populations are thought to be recoverable by making existing and fragmented habitat patches more connected via ‘corridors’ of suitable habitat. The research highlighted here suggests that more emphasis should be placed instead on building up existing population sizes and ensuring food availability is relatively constant instead of worrying about how many trickling migrants might be moving back and forth. This essentially means that a few skinny corridors connecting population fragments will probably be insufficient to save our imperilled species.
Franzen, M., & Nilsson, S. (2009). Both population size and patch quality affect local extinctions and colonizations Proceedings of the Royal Society B: Biological Sciences DOI: 10.1098/rspb.2009.1584
Griffen, B., & Drake, J. (2009). Environment, but not migration rate, influences extinction risk in experimental metapopulations Proceedings of the Royal Society B: Biological Sciences DOI: 10.1098/rspb.2009.1153
Today I highlight a new paper just out online in Diversity and Distributions by James Watson and colleagues: Wilderness and future conservation priorities in Australia. It’s certainly one for the Potential list.
Jim Jim Falls, Kakadu National Park
Australia has a pretty bad biodiversity conservation track record – we have some of the worst mammal extinction trends in the world, and we’ve lost at least 50 % of our forested area since European colonisation. Despite our relatively large system of parks and reserves, things aren’t going to well (even in the parks!).
Our rapidly expanding influence means that we have to start protecting larger and larger areas if we want to have any chance of slowing the modern extinction crisis. This means we have to go beyond dedicated biodiversity reserves and sequester more ‘wilderness’ (defined as “…large areas that have experienced minimal habitat loss“). Watson and colleagues therefore used Australia as a good example to determine the extent to which the national protected area network captures ‘wilderness’, and how Australia’s planned expansion of the reserve system will include ‘wilderness’ in the future.
Although there wasn’t much planning involved initially, Australia (like many other countries) started to take biodiversity conservation seriously in the mid-1990s, such that now we have about 11 % of our 7.7 million km2 land area within a National Reserve System. Planning didn’t feature heavily in the early years, but it has been embraced now by nearly all planning bodies within government.
© Wiley-Blackwell
Using estimates of the total wilderness area in Australia (Fig. a), Watson and colleagues determined how much was included in the Reserve System (Fig. b), and how this value changed between 2000 and 2006.
Of the 2.93 million km2 of wilderness (38 % of land area, mostly in northern and western Australia), only 14 % was protected in 2000. This value increased marginally to 19 % by 2006 as the size of the Reserve System itself increased by 37 % (i.e., from 652597 to 895326 km2).
Bottom line – our growth in reserve area didn’t really capture the necessary wilderness; instead, gains were made in areas largely modified by humans. Even where wilderness has been captured, it’s predominately in ‘multiple use’ regions (incorporating mining, forestry and grazing, for example).
This isn’t a bad thing really – by focussing on areas of high biodiversity value that are under relatively high threat embraces the biodiversity hotspot approach to conservation and emphasises restoration. This is, of course, needed. But not incorporating a wider component of the habitats within wilderness could bias conservation toward range-restricted species.
© Wiley-Blackwell
Watson and colleagues therefore make a number of recommendations:
The bottom line is that we need to find a better balance between planning that protects threatened species and ecosystems in already highly fragmented (threatened) landscapes, and planning that protects large areas of wilderness that still contains most of its conservation values (wilderness). We’re getting there, but slowly, and hopefully in time to save our remaining threatened species from extinction.
Watson, J., Fuller, R., Watson, A., Mackey, B., Wilson, K., Grantham, H., Turner, M., Klein, C., Carwardine, J., Joseph, L., & Possingham, H. (2009). Wilderness and future conservation priorities in Australia Diversity and Distributions DOI: 10.1111/j.1472-4642.2009.00601.x
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.
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