Tropical forest resilience depends on past disturbance frequency

16 07 2014

I’ve recently come across an interesting study that perfectly marries palaeo-ecological data with modern conservation philosophy. It’s not often that such a prehistorical perspective dating at least to the Last Glacial Maximum has been used so effectively to inform future conservation outlooks. I’m particularly interested in this sort of approach considering my own palaeo dabblings of late.

Published in Nature Communications this May, Lydia Cole and colleagues’ paper Recovery and resilience of tropical forests after disturbance is a meta-analysis of 71 studies covering nearly 300 disturbance events in tropical forests over the last 20,000 years or so. Using fossil pollen records as an index of vegetation change, they demonstrated the (somewhat intuitive) main result that the time to recovery following a disturbance generally decreases as the past disturbance frequency increased.

This appears to be a vindication of the idea that a system’s adaptive strategies evolve as a product of the local disturbance regime. More importantly, they found that recovery was faster following ‘large infrequent events’, which are natural perturbations such as cyclones and major fires. While most past disturbances were caused by humans clearing forest, the fact that tropical forest systems were most resilient to ‘natural’ events means that if we can’t stop human disturbances, at least we can attempt to emulate natural processes to maximise the rebound potential. Much like many modern forestry operations try to emulate natural disturbances to limit their damage, we should at least manage our impacts by understanding so-called ‘natural’ regimes as much as possible. Read the rest of this entry »





50/500 or 100/1000 debate not about time frame

26 06 2014

Not enough individualsAs you might recall, Dick Frankham, Barry Brook and I recently wrote a review in Biological Conservation challenging the status quo regarding the famous 50/500 ‘rule’ in conservation management (effective population size [Ne] = 50 to avoid inbreeding depression in the short-term, and Ne = 500 to retain the ability to evolve in perpetuity). Well, it inevitably led to some comments arising in the same journal, but we were only permitted by Biological Conservation to respond to one of them. In our opinion, the other comment was just as problematic, and only further muddied the waters, so it too required a response. In a first for me, we have therefore decided to publish our response on the arXiv pre-print server as well as here on ConservationBytes.com.

50/500 or 100/1000 debate is not about the time frame – Reply to Rosenfeld

cite as: Frankham, R, Bradshaw CJA, Brook BW. 2014. 50/500 or 100/1000 debate is not about the time frame – Reply to Rosenfeld. arXiv: 1406.6424 [q-bio.PE] 25 June 2014.

The Letter from Rosenfeld (2014) in response to Jamieson and Allendorf (2012) and Frankham et al. (2014) and related papers is misleading in places and requires clarification and correction, as follows: Read the rest of this entry »





A convenient truth: global push for carbon-based conservation

19 05 2014

Eucalyptus viminalis (Manna Gum) - leaf, adultI’ve just written an article for the Australian River Restoration Centre‘s RipRap magazine, and they have given me permission to reproduce it here.

The brave, new green world of the carbon economy hasn’t exactly taken off as desired. Perhaps it’s because it wasn’t really planned from the outset, or maybe it is still too abstract for most people to accept, digest and incorporate into their daily lives. An emergent property of society’s generally slow awakening to the challenge of climate disruption, is that it will be a long time before we accept its full suite of incarnations.

The infant carbon economy is, however, well and truly alive and kicking, so it is important to try and plan for its growing influence on our decision making. Bumps in the road aside, the carbon economy has mostly been a blessing (actual and potential) for biodiversity conservation projects the world over.

In principle, the aim of the carbon economy is rather straight-forward: charge people a certain amount for each unit of carbon dioxide equivalents they release, and then use that money to develop approaches that further increase carbon sequestration or limit emissions. It’s a ‘build-it-and-they-will-come’ framework, where increasing financial impetus to restrict emissions is enhanced by society’s evolution towards better approaches and technology.

The operational side of the carbon economy is unfortunately much more muddled, with vested interests and political gaming weakening its implementation. Nonetheless, we persevere. Read the rest of this entry »





South Australia’s tattered environmental remains

16 04 2014
State budget percentage expenditures for health, education and environment

South Australia State budget percentage expenditures for health, education and environment

Yesterday I gave the second keynote address at the South Australia Natural Resource Management (NRM) Science Conference at the University of Adelaide (see also a brief synopsis of Day 1 here). Unfortunately, I’m missing today’s talks because of an acute case of man cold, but at least I can stay at home and work while sipping cups of hot tea.

Many people came up afterwards and congratulated me for “being brave enough to tell the truth”, which both encouraged and distressed me – I am encouraged by the positive feedback, but distressed by the lack of action on the part of our natural resource management leaders.

The simple truth is that South Australia’s biodiversity and ecosystems are in shambles, yet few seem to appreciate this.

So for the benefit of those who couldn’t attend, I’ve uploaded the podcast of my slideshow for general viewing here. I’ve also highlighted some key points from the talk below: Read the rest of this entry »





Australia’s (latest) war on the environment

3 03 2014

monkYes, the signs were there, but they weren’t clandestine messages written in the stars or in the chaos of tea-leaf dregs. We saw this one coming, but Australians chose to ignore the warning signs and opt for the American political model of extremism, religiosity, plutocracy and science denial.

Enter the ‘Tea Party’ of Australia – the ‘new’ Coalition where reigning Rex perditor Prime Minister Tony The Monk Abbott1 has, in just a few short months, turned back the clock on Australian environmental protection some 40 years.

Yes, we saw it coming, but it wasn’t a tautological fait accompli just because it concerned a ‘conservative’ government. It’s difficult to remember, I know, that conservative governments of yesteryear implemented some strikingly powerful and effective environmental legislation. Indeed, it was the former incarnation of the Coalition government that implemented the once-formidable Environmental Protection and Biodiversity Conservation (EPBC) Act under the direction of then Environment Minister, Robert Hill. A colossus of sorts, the EPBC suffers from many ailments. While it’s the only really bitey environmental legislation we’ve got, that colossus is a lumbering, limping giant missing more than a few teeth – it needs a complete overhaul.

As most Australians are unfortunately aware, The Monk repeatedly and defiantly promised to repeal the Labor-government carbon price implemented in July 2012, despite the absolute necessity to tax the heaviest pollutersWhile somewhat sheepish about his recent climate disruption denialism following his election in 2013, a denialist he remains:

Let us re-familiarise ourselves with some of his historical pearlers: Read the rest of this entry »





More species = more resilience

8 01 2014

reef fishWhile still ostensibly ‘on leave’ (side note: Does any scientist really ever take a proper holiday? Perhaps a subject for a future blog post), I cannot resist the temptation to blog about our lab’s latest paper that just came online today. In particular, I am particularly proud of Dr Camille Mellin, lead author of the study and all-round kick-arse quantitative ecologist, who has outdone herself on this one.

Today’s subject is one I’ve touched on before, but to my knowledge, the relationship between ‘diversity’ (simply put, ‘more species’) and ecosystem resilience (i.e., resisting extinction) has never been demonstrated so elegantly. Not only is the study elegant (admission: I am a co-author and therefore my opinion is likely to be biased toward the positive), it demonstrates the biodiversity-stability hypothesis in a natural setting (not experimental) over a range of thousands of kilometres. Finally, there’s an interesting little twist at the end demonstrating yet again that ecology is more complex than rocket science.

Despite a legacy of debate, the so-called diversity-stability hypothesis is now a widely used rule of thumb, and its even implicit in most conservation planning tools (i.e., set aside areas with more species because we assume more is better). Why should ‘more’ be ‘better’? Well, when a lot of species are interacting and competing in an ecosystem, the ‘average’ interactions that any one species experiences are likely to be weaker than in a simpler, less diverse system. When there are a lot of different niches occupied by different species, we also expect different responses to environmental fluctuations among the community, meaning that some species inherently do better than others depending on the specific disturbance. Species-rich systems also tend to have more of what we call ‘functional redundancy‘, meaning that if one species providing an essential ecosystem function (e.g., like predation) goes extinct, there’s another, similar species ready to take its place. Read the rest of this entry »





King for a day – what conservation policies would you make?

29 11 2013

CrownI have been thinking a lot lately about poor governance and bad choices when it comes to biodiversity conservation policy. Perhaps its all that latent anger arising from blinkered, backward policies recently implemented by conservative state and national governments in Australia and elsewhere that leads me to contemplate: What would I do if I had the power to change policy?

While I am certain I have neither the experience or complete knowledge to balance national budgets, ensure prosperity and maintain the health of an entire country, I do have some ideas about what we’re doing wrong conservation-wise, and how we could potentially fix things. This is not meant to be an exhaustive list – it is more a discussion point where people can suggest their own ideas.

So here are 16 things I’d change or implement (mainly in Australia) if I were king for a day:

Read the rest of this entry »





Quantity, but not quality – slow recovery of disturbed tropical forests

8 11 2013

tropical regrowthIt is a sobering statistic that most of the world’s tropical forests are not ‘primary’ – that is, those that have not suffered some alteration or disturbance from humans (previously logged, cleared for agriculture, burned, etc.).

Today I highlight a really cool paper that confirms this, plus adds some juicy (and disturbing – pun intended – detail). The paper by Phil Martin and colleagues just published in Proceedings of the Royal Society B came to my attention through various channels – not least of which was their citation of one of our previous papers ;-), as well as a blog post by Phil himself. I was so impressed with it that I made my first Faculty of 1000 Prime recommendation1 of the paper (which should appear shortly).

As we did in 2011 (to which Phil refers as our “soon-to-be-classic work” – thanks!), Martin and colleagues amassed a stunning number of papers investigating the species composition of disturbed and primary forests from around the tropics. Using meta-analysis, they matched disturbed and undisturbed sites, recording the following statistics: Read the rest of this entry »





Conservation: So easy a child could do it

13 09 2013

child's playI don’t like to talk about my family online. Call me paranoid, but there are a lot of crazy people out there who don’t like what scientists like me are saying (bugger the evidence). Yes, like many climate scientists, I’ve also been threatened. That’s why my personal life remains anonymous except for a select group of people.

But I’ve mentioned my daughter before on this blog, and despite a few people insinuating that I am a bad parent because of what I said, I am happy that I made the point that climate change is a scary concept of which our children must at least be cognisant.

My daughter’s story today is a little less confronting, but equally enlightening. It’s also a little embarrassing as a scientist who has dedicated my entire research career to the discipline of conservation biology.

As a normal six year-old without the ability to refrain from talking – even for a moment – I hear a lot of stories. Many of them are of course fantastical and ridiculous, but those are just part of a healthy, imaginative childhood (I am proud to say though that she is quite clear about the non-existence of fictitious entities like faeries, easter bunnies and gods).

Every once in a while, however, there are snippets of wisdom that ooze out from the cracks in the dross. In the last few months, my daughter has independently and with no prompting from me come up with two pillars of conservation science: (i) protected areas and (ii) biodiversity corridors. Read the rest of this entry »





Brave new green world: biodiversity’s response to Australia’s carbon economy

12 03 2013

carbon farming 2I’ve had a busy weekend entertaining visiting colleagues and participating in WOMADelaide‘s first-ever ‘The Planet Talks‘. If you haven’t heard of WOMADelaide, you’re truly missing out in one of the best music festivals going (and this is from a decidedly non-festival-going sort). Planet Talks this year was a bit of an experiment after the only partially successful Earth Station festival held last year (it was well-attended, but apparently wasn’t as financially successful as they had hoped). So this year they mixed a bit of science with a bit of music – hence ‘Planet Talks’. Paul Ehrlich was one of the star attractions, and I had the honour of going onstage with him yesterday to discuss a little bit about human population growth and sustainability. It was also great to see Robyn Williams again. All the Talks were packed out – indeed, I was surprised they were so popular, especially in the 39-degree heat. Rob Brookman, WOMADelaide’s founder and principal organiser, told me afterward that they’d definitely be doing it again.

But my post really isn’t about WOMADelaide or The Planet Talks (even though I got the bonus of meeting one of my favourite latin bands, Novalima, creators of one of my favourite songs). It’s instead about a paper I heralded last year that’s finally been accepted.

In early 2012 at the Terrestrial Ecosystem Research Network (TERN) symposium in Adelaide, the Australian Centre for Ecological Analysis and Synthesis (ACEAS) put on what they called the ‘Grand Challenges’ workshop. I really didn’t get the joke at the time, but apparently the ‘grand challenge’ was locking 30 scientists with completely different backgrounds in a room for two days to see if they could do anything other than argue and bullshit. Well, we rose to that challenge and produced something that I think is rather useful.

I therefore proudly introduce the paper entitled Brave new green world: consequences of a carbon economy for the conservation of Australian biodiversity just accepted in Biological Conservation. The online version isn’t quite ready yet (should be in the next few weeks), but you are welcome to request a preprint from me now. If you attended (the surprisingly excellent) TERN symposium in Canberra last month, you might have seen me give a brief synopsis of our results.

The paper is a rather  in-depth review of how we, 30 fire, animal, plant, soil, landscape, agricultural and freshwater biologists, believe Australia’s new carbon-influenced economy (i.e., carbon price) will impact the country’s biodiversity. Read the rest of this entry »





Experiments in carbon-biodiversity trade-offs

19 07 2012

Last month I covered a topic that is not only becoming the latest fashion-trend in conservation, it is also where much of the research funding is going. Whether or not this is the best use of limited research resources is largely irrelevant – as I always preach to fledgling grant writers: “Write about what the funding agency wants to fund, not what you want to do”. Cynical, I know, but it is oh-so-true.

The topic in question is how we as conservation biologists ensure that the new carbon economy drives positive change for biodiversity, rather than the converse. Hell knows we really can’t afford for land-use change to get any worse for biodiversity; worldwide we are on trajectory for a mass extinction within our lifetime, so anything that potentially makes it worse should be squashed completely.

But it seems that land- and seascape changes that might arise from trading carbon (including carbon pricing) are on a knife-edge as far as biodiversity is concerned. I described this dilemma in my previous post, and I am happy to say that the manuscript arising is almost complete. Briefly, if we as a society decide to try to reduce greenhouse gas emissions and capture as much carbon as possible by altering land-use practices, then it is likely that our forests will become vast monocultures incapable of sustaining much biodiversity at all. In other words, there’s a balance to be struck between what is good for carbon sequestration and what is good for biodiversity. While not always mutually exclusive, neither are they mutually attainable goals. Read the rest of this entry »





The wounded soldiers of biodiversity

10 04 2012

Here’s another great post from Salvador Herrando-Pérez. It is interesting that he’s chosen an example species that was once (a long, long time ago in a galaxy far, far away) of great interest to me (caribou – see ancient papers a, b, c, d). But that is another story. Take it away, Salva.

 

Figure 1. Caribou (reindeer) are ungulates weighing up to ~ 100 kg. They live in tundra and taiga in Finland, Greenland, Finland, Norway, Mongolia, Russia, Canada and USA (extinct in Sweden). The species is globally stable (‘Least Concern’, IUCN Red List), but the subspecies of woodland caribou (Rangifer tarandus caribou) is threatened in North America. Schneider and colleagues’ 7 study encompasses ~ 3,000 individuals in 12 herds (75 to 450 individuals per herd), occupying ~ 100.000 km2 of conifer forest and peatland (3,000 to 19,000 km2 per herd). Two ecotypes are recognized regionally22, namely migratory mountain herds (mostly from mountains and foothills in west-central Alberta), and non-migratory boreal herds (mostly from peatlands in central and northern Alberta). The photo shows a group of caribous grazing on subalpine vegetation from Tonquin Valley, Jasper National Park (Alberta, Canada). Photo courtesy of Saakje Hazenberg.

As conservation biology keeps incorporating management and economical principles from other disciplines, it stumbles with paradoxes such that investing on the most threatened components of biodiversity might in turn jeopardize the entire assets of biodiversity.

At the end of 2011, newspapers and TVs echoed an IUCN report cataloguing as ‘extinct’ or ‘near extinct’ several subspecies of rhinos in Asia and Africa. To many, such news might have invoked the topic: “how badly governments do to protect the environment”. However if, to avoid those extinctions, politicians had to deviate funds from other activities, what thoughts would come to the mind of workers whose salaries had to be frozen, school directors whose classroom-roof leakages could not be repaired (e.g., last winter at my niece’s school in Spain), colonels whose last acquisition of ultramodern tanks had to be delayed, or our city council’s department who had to cancel Sting’s next performance.

Thus, there are three unquestionable facts regarding species conservation:

  1. the protection of species costs money;
  2. governments and environmental organisations have limited budgets for a range of activities they deem necessary; and
  3. our way of conserving nature is failing because, despite increasing public/private support and awareness, the rate of destruction of biodiversity is not decelerating1,2.

One of the modern debates among conservationists pivots around how to use resources efficiently3-6. Schneider and colleagues7 have dealt with this question for woodland caribou (Rangifer tarandus) in Canada. A total of 18 populations of this ungulate persist in the Canadian province of Alberta, all undergoing demographic declines due to mining extractions (oil, gas and bitumen), logging and wolf predation. The species is listed as ‘threatened’ regionally and nationally. The Alberta Caribou Recovery Plan (2004-2014) is attempting to protect all herds. Under such a framework, Schneider et al.7 predicted that woodland caribou would be regionally extirpated in less than a century.

Furthermore, they estimated the costs of making each herd viable (Fig. 1), with a triple revelation. To save all herds from extinction would need ~ CA$150,000 million (beyond the available budget). The most threatened herds are among the most expensive to protect (within present management approach). Some herds would be secured through modest investment for two decades. Overall, their study suggests that Alberta’s woodland caribou would be eligible for triage, i.e., at the subpopulation level8. Read the rest of this entry »





Marine protected areas: do they work?

13 08 2010

One measure that often meets great resistance from fishermen, but is beloved by conservationists, is the establishment of marine protected or ‘no take’ areas.” Stephen J. Hall (1998)

I’m going to qualify this particular post with a few disclaimers; first, I am not involved in the planning of any marine protected areas (henceforth referred to as ‘marine parks’) in Australia or elsewhere; and second, despite blogging on the issue, I have never published in the discipline of protected area design (i.e, ‘conservation planning’ is not my area of expertise).

That said, it seems to becoming more imperative that I enter the fray and assess not only how marine parks should be designed, but how effective they really are (or can be). I’ve been asked by several conservation NGOs to provide some insight into this, so I thought I should ‘think aloud’ and blog a little mini-review about marine park effectiveness.

Clearly there is a trend to establish more marine parks around the world, and this is mainly because marine conservation lags so far behind terrestrial conservation. Indeed, Spalding et al. (2008) showed that only 4.1 % of continental shelf areas are incorporated within marine parks, and ~ 50 % of all marine ecoregions have less than 1 % marine park coverage across the shelf. Furthermore, marine protection is greatest in the tropical realms, while temperate realms are still poorly represented.

The question of whether marine parks ‘work’ is, however, more complicated than it might first appear. When one asks this question, it is essential to define how the criteria for success are to be measured. Whether it’s biodiversity protection, fisheries production, recreational revenue, community acceptance/involvement or some combination of the above, your conclusion is likely to vary from place to place.

Other complications are, of course, that if you cannot ensure a marine park is adequately enforced (i.e., people don’t respect the rules) or if you don’t actually place the park anywhere near things that need protecting, there will be no real net benefit (for any of the above-mentioned interest groups). Furthermore, most marine parks these days have many different types of uses allowed in different zones (e.g., no fishing, some fishing, recreational diving only, no boat transport, some shipping, etc., etc., etc.), so it gets difficult to test for specific effects (it’s a bit like a cap-and-trade legislation for carbon – too many rules and often no real net reduction in carbon emissions – but that’s another story).

All these conditions aside, I think it’s a good idea to present what the real experts have been telling us about marine park effectiveness from a biodiversity and fishing perspective over the last decade or so. I’ll summarise some of the major papers here and give an overall assessment at the end. I do not contend that this list is even remotely comprehensive, but it does give a good cross-section of the available evidence. Read the rest of this entry »





Put the bite back into biodiversity conservation

2 07 2010

Today’s guest post is by Dr. Euan Ritchie, formerly of James Cook University, but who is now firmly entrenched at Deakin University in Victoria as a new Lecturer in ecology. Euan’s exciting research over the course of his memorable PhD (under the tutelage of renowned ecologist-guru, Professor Chris Johnson) has produced some whoppingly high-impact research. This latest instalment highlights a series of related papers he and his colleagues have just produced. We’re fortunate he agreed to give us his thoughts. Interestingly, the topic was just highlighted in the last issue of NatureDon’t damage dingos.

Corey has invited me to report on a recent paper published in Ecology Letters and another related study in PloS One, which together show how a better understanding of dingoes and their social structure and associated behaviour can help us to maintain or improve the health of our terrestrial ecosystems. This work, led by PhD student Arian Wallach (University of Adelaide), and involving collaborations with John Read (University of Adelaide), Adam O’Neill (C&A Environmental Services) and Christopher Johnson and me (James Cook University), offers some of the strongest evidence yet of the key roles top predators play in maintaining the balance.

Invasive species, along with habitat loss and the impacts of climate change, are among the greatest threats to the continued survival of many species. Because of this, millions of dollars and time is spent each year to control their populations. The impacts of invasive species in Australia are sadly all too obvious, with nearly half of the world’s mammal extinctions in the last 200 years occurring in Australia, with the prime suspects being the introduced domestic cat and red fox. However, despite massive, costly and ongoing attempts to control fox and cat populations successfully, we continue to witness the decline of many of our native species. Why? We would argue that the problem is that for too long much of our conservation and management efforts have been focused on treating symptoms and not the cause, which is the loss of ecosystem resilience (the natural ability of ecosystems to withstand change).

Read the rest of this entry »





What is a species?

18 09 2009

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.

butterfliesSpecies, 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?

birds

© 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

© 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.





Conservation Scholars: David Lindenmayer

10 09 2009

The Conservation Scholars series highlights leaders in conservation science and includes a small biography, a list of major scientific publications and a Q & A on each person’s particular area of expertise.

David LindenmayerOur fourteenth Conservation Scholar is one of Australia’s better known conservation ecologists: David Lindenmayer. David has been battling for landscape ecology and conservation science to be taken seriously in this country for over 30 years. I recently featured David here at ConservationBytes.com on the importance of incorporating ecological knowledge into Australian bushfire policy, but here’s a more comprehensive coverage of his legacy.

Biography

I am a Research Professor at the Fenner School of Environment & Society at The Australian National University (ANU). I have worked at the ANU for over 17 years and have developed a speciality for establishing and maintaining large-scale, long-term empirical studies. These span wet forests (in Victoria), plantation forests (at Tumut in southern NSW), temperate woodlands (throughout south-western NSW) and coastal heathlands (at Jervis Bay Territory, southern NSW). We examine the response of different groups of biota (birds, mammals, reptiles, frogs, invertebrates and plants) to human or natural interventions in these studies – e.g., logging, plantation development, agricultural and revegetation, fire (wildfire and prescribed burning). We also have projects that attempt to integrate data and ecological insights across these major projects. These major programs have many (> 75) live projects embedded within them, including an array of post-graduate students.radiotracking1

The work we do has some key themes. First, it needs to be underpinned by careful statistical design and we have 3 professional statisticians in our group that have critical experimental design roles in all of our studies. Second, we build significantly upon long-term datasets to quantify longitudinal responses of biota to agents of change. Third, we work closely with land managers and government agencies to increase the chances of our work being adopted on the ground. Fourth, and related to the previous point, we work very hard to communicate our empirical results to a broad audience by publishing semi-popular books and other kinds of communication products.

Our group currently comprises ~ 30 people and the younger scientists in the team are a truly exciting part of its dynamism. Indeed, the best research is usually done by post-graduate researchers!! Our hope is to maintain the research and teaching momentum that we have generated over the past decade to keep the group a vibrant, active and forward-thinking one for several decades to come.

Major Publications

It is difficult to choose some papers above others. But I do like the major empirical ones we have done because large synthesis of field data are not common these days – in an age where the emphasis is on short, ‘newsy’ pieces. I also like writing books and longer review articles because these are a chance to pull together a lot of information and make sense of the literature out there.

Questions and Answers

radiotracking21. You are probably best known for your work on vertebrate responses to forested landscape change. What kind of data and studies are needed to gauge how biodiversity responds to such changes?

It is clear to me that there is a paucity of large-scale, long-term datasets really to develop an empirical understanding of what is happening in a changing world. This is what our group does really well I think, so it is a real privilege to be able to do that.

2. Your book, Practical Conservation Biology, is a great introduction to applied conservation. Can you describe what you mean by ‘practical’ and how aspiring students need to approach conservation science?

The aim of the PCB book was to provide students with the thinking and some (and I stress just some) of the tools to tackle real world problems. I am not sure that we succeeded in doing this, but it was a good thing to attempt. I also think it was important to showcase Australian conservation biology because there are some many outstanding researchers and practitioners in this country.

3. Fire management is a ‘hot’ issue (excuse the pun) in Australia and beyond, yet there still seems to be little uptake of good fire disturbance ecology by policy makers. What do we need to be doing differently at the policy level, and how can we facilitate better uptake of landscape disturbance ecology?

This is a tough question because so often fire management issues are hijacked by the emotion that is associated with major natural disturbance events. The issue here is that the science of fire and the science of conservation and environmental management need to be better intersected to examine how to best tackle resource management problems. Policy somehow needs to remain cold to all the emotion that humans throw, often illogically at resource management problems. Otherwise I see that policy making in crisis mode will risk perverse outcomes that will be poor management practice and have negative effects on biodiversity.

4. In your opinion, what are the some of the best ways Australia can improve its poor environmental record and reclaim some of its dwindling biodiversity heritage?

Australian needs to get serious about properly resourcing environmental management and biodiversity conservation. We have endless reports about what to do, yet this rarely transfers to serious things on the ground. Nor does environmental legislation really protect the environment and biodiversity. We also need to get serious about long-term datasets to get somewhere sensible with understanding long-term changes in biota.

CJA Bradshaw

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Wobbling to extinction

31 08 2009

crashI’ve been meaning to highlight for a while a paper that I’m finding more and more pertinent as a citation in my own work. The general theme is concerned with estimating extinction risk of a particular population, species (or even ecosystem), and more and more we’re finding that different drivers of population decline and eventual extinction often act synergistically to drive populations to that point of no return.

In other words, the whole is greater than the sum of its parts.

In other, other words, extinction risk is usually much higher than we generally appreciate.

This might seem at odds with my previous post about the tendency of the stochastic exponential growth model to over-estimate extinction risk using abundance time series, but it’s really more of a reflection of our under-appreciation of the complexity of the extinction process.

In the early days of ConservationBytes.com I highlighted a paper by Fagan & Holmes that described some of the few time series of population abundances right up until the point of extinction – the reason these datasets are so rare is because it gets bloody hard to find the last few individuals before extinction can be confirmed. Most recently, Melbourne & Hastings described in a paper entitled Extinction risk depends strongly on factors contributing to stochasticity published in Nature last year how an under-appreciated component of variation in abundance leads to under-estimation of extinction risk.

‘Demographic stochasticity’ is a fancy term for variation in the probability of births deaths at the individual level. Basically this means that there will be all sorts of complicating factors that move any individual in a population away from its expected (mean) probability of dying or reproducing. When taken as a mean over a lot of individuals, it has generally been assumed that demographic stochasticity is washed out by other forms of variation in mean (population-level) birth and death probability resulting from vagaries of the environmental context (e.g., droughts, fires, floods, etc.).

‘No, no, no’, say Melbourne & Hastings. Using some relatively simple laboratory experiments where environmental stochasticity was tightly controlled, they showed that demographic stochasticity dominated the overall variance and that environmental variation took a back seat. The upshot of all these experiments and mathematical models is that for most species of conservation concern (i.e., populations already reduced below to their minimum viable populations size), not factoring in the appropriate measures of demographic wobble means that most people are under-estimating extinction risk.

Bloody hell – we’ve been saying this for years; a few hundred individuals in any population is a ridiculous conservation target. People must instead focus on getting their favourite endangered species to number at least in the several thousands if the species is to have any hope of persisting (this is foreshadowing a paper we have coming out shortly in Biological Conservationstay tuned for a post thereupon).

Melbourne & Hastings have done a grand job in reminding us how truly susceptible small populations are to wobbling over the line and disappearing forever.

CJA Bradshaw

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Ray of conservation light for Borneo

25 07 2009

This was the most interesting 20 minutes I’ve spent in the last wee while.

Up until just now, I had never heard of Willie Smits or what he’s been doing in Indonesia. I’ve been fairly hard on Indonesia in some of my papers and blog posts because of the ecological tragedy taking place there. I’ve focussed on the immense rate and extent of deforestation, the oil palm explosion, peatland destruction and air pollution arising from runaway fires there – I have thus far ignored any real positives because I didn’t really believe there were any.

Then I saw Smits’ TED talk. Two words – very impressed. I usually enjoy and even barrack for TED talks, and this is no exception.

This man and his organisation have really been applying a great deal of the research mentioned on ConservationBytes.com, as well as collecting data proving beyond a shadow of a doubt that if you integrate people’s needs with those of biodiversity, you can restore not only entire ecosystems, you can make humans benefit immensely in the process. A chronic pessimist, I can scarcely believe it.

He talks about a whole-system approach where agriculture, full rain forest restoration, climate control, carbon sequestration, monitoring and local governance all work together to turn once bare, fire-prone, species-poor deforested grasslands into teaming jungles that support happy, healthy, wealthy and well-governed human communities. Please watch this.

CJA Bradshaw

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June Issue of Conservation Letters

6 06 2009

Quick off the mark this month is the new issue of Conservation Letters. There are some exciting new papers (listed below). I encourage readers to have a look:

Policy Perspectives

Letters

CJA Bradshaw





Realising you’re a drunk is only the first step

11 05 2009

© A. Savchenko

© A. Savchenko

I recently did an interview for the Reef Tank blog about my research, ConservationBytes.com and various opinions about marine conservation in general. I’ve been on about ‘awareness’ raising in biodiversity conservation over the last few weeks (e.g., see last post), saying that it’s really only the first step. To use an analogy, alcoholics must first recognise and accept that they are indeed drunks with a problem before than can take the (infamous AA) steps to resolve it. It’s not unlike biodiversity conservation – I think much of the world is aware that our forests are disappearing, species are going extinct, our oceans are becoming polluted and devoid of fish, our air and soils are degraded to the point where they threaten our very lives, and climate change has and will continue to exacerbate all of these problems for the next few centuries at least (and probably for much longer).

We’ve admitted we have a disease, now let’s do something about it.

Read the full interview here.

CJA Bradshaw

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