What conservationists should recommend to philanthropists

24 08 2015

business-people-forest-sqIt probably won’t come as too much of a surprise that most of the people I know reasonably well (mates included) are also scientists of some description. I therefore think that I fall into the extremely normal and mundane category of associating the most with people at work. Sure, I’ve also got very good mates who are et alia plumbers, chefs, winemakers (I do live in South Australia, after all), mechanics, coffee roasters and farmers (I also live on a small farm), so at least a get out of the office a bit. In summary, I tend to befriend and hang around people who are for the most part making ends meet, but who are by no means in a position to spend oodles of cash on anything remotely related to the conservation of biodiversity.

From time to time, however, I do meet extremely wealthy people, but we generally do not operate in the same social circles (I know, another big surprise). Nonetheless, I keep finding myself in conversations with such people that start along the lines of the following question:

“What’s the most effective way to invest money to save species from going extinct?”

As the Australian saying goes: “How long is a piece of string” – in other words, it’s a difficult, multi-dimensional answer at best, or a confused non sequitur one at worst.

Those reading this might be thinking right now, “Oh, I know exactly what I’d spend it on if I had that kind of money”, but after a few moments of contemplation, you might not be so sure. This is the dilemma in which I’ve found myself now on more than a few occasions.

So, with the benefit of a little contemplation, here are a few of my thoughts on the subject. Read the rest of this entry »





Ice Age? No. Abrupt warmings and hunting together polished off Holarctic megafauna

24 07 2015
Oh shit oh shit oh shit ...

Oh shit oh shit oh shit …

Did ice ages cause the Pleistocene megafauna to go extinct? Contrary to popular opinion, no, they didn’t. But climate change did have something to do with them, only it was global warming events instead.

Just out today in Science, our long-time-coming (9 years in total if you count the time from the original idea to today) paper ‘Abrupt warmings drove Late Pleistocene Holarctic megafaunal turnover‘ demonstrates for the first time that abrupt warming periods over the last 60,000 years were at least partially responsible for the collapse of the megafauna in Eurasia and North America.

You might recall that I’ve been a bit sceptical of claims that climate changes had much to do with megafauna extinctions during the Late Pleistocene and early Holocene, mainly because of the overwhelming evidence that humans had a big part to play in their demise (surprise, surprise). What I’ve rejected though isn’t so much that climate had nothing to do with the extinctions; rather, I took issue with claims that climate change was the dominant driver. I’ve also had problems with blanket claims that it was ‘always this’ or ‘always that’, when the complexity of biogeography and community dynamics means that it was most assuredly more complicated than most people think.

I’m happy to say that our latest paper indeed demonstrates the complexity of megafauna extinctions, and that it took a heap of fairly complex datasets and analyses to demonstrate. Not only were the data varied – the combination of scientists involved was just as eclectic, with ancient DNA specialists, palaeo-climatologists and ecological modellers (including yours truly) assembled to make sense of the complicated story that the data ultimately revealed. Read the rest of this entry »





Avoiding genetic rescue not justified on genetic grounds

12 03 2015
Genetics to the rescue!

Genetics to the rescue!

I had the pleasure today of reading a new paper by one of the greatest living conservation geneticists, Dick Frankham. As some of CB readers might remember, I’ve also published some papers with Dick over the last few years, with the most recent challenging the very basis for the IUCN Red List category thresholds (i.e., in general, they’re too small).

Dick’s latest paper in Molecular Ecology is a meta-analysis designed to test whether there are any genetic grounds for NOT attempting genetic rescue for inbreeding-depressed populations. I suppose a few definitions are in order here. Genetic rescue is the process, either natural or facilitated, where inbred populations (i.e., in a conservation sense, those comprising too many individuals bonking their close relatives because the population in question is small) receive genes from another population such that their overall genetic diversity increases. In the context of conservation genetics, ‘inbreeding depression‘ simply means reduced biological fitness (fertility, survival, longevity, etc.) resulting from parents being too closely related.

Seems like an important thing to avoid, so why not attempt to facilitate gene flow among populations such that those with inbreeding depression can be ‘rescued’? In applied conservation, there are many reasons given for not attempting genetic rescue: Read the rest of this entry »





It’s all about the variation, stupid

12 01 2015

val-1-3It is one of my long-suffering ecological quests to demonstrate to the buffoons in government and industry that you can’t simply offset deforestation by planting another forest elsewhere. While it sounds attractive, like carbon offsetting or even water neutrality, you can’t recreate a perfectly functioning, resilient native forest no matter how hard you try.

I’m not for a moment suggesting that we shouldn’t reforest much of what we’ve already cut down over the last few centuries; reforestation is an essential element of any semblance of meaningful terrestrial ecological restoration. Indeed, without a major commitment to reforestation worldwide, the extinction crisis will continue to spiral out of control.

What I am concerned about, however, is that administrators continue to push for so-called ‘biodiversity offsets’ – clearing a forest patch here for some such development, while reforesting or even afforesting another degraded patch there. However, I’ve blogged before about studies, including some of my own, showing that one simply cannot replace primary forests in terms of biodiversity and long-term carbon storage. Now we can add resilience to that list.

While I came across this paper a while ago, I’ve only found the time to blog about it now. Published in PLoS One in early December, the paper Does forest continuity enhance the resilience of trees to environmental change?1 by von Oheimb and colleagues shows clearly that German oak forests that had been untouched for over 100 years were more resilient to climate variation than forests planted since that time. I’ll let that little fact sink in for a moment … Read the rest of this entry »





We treat our wildlife like vermin

24 09 2014
Just a little of the dog fence's carnage and cruelty at work.

Just a little of the dog fence’s carnage and cruelty at work.

I’ve pointed out in several posts on ConservationBytes.com just how badly Australia is doing in the environmental stakes, with massive deforestation continuing since colonial times, feral predators and herbivores blanketing the continent, inadequate protected areas, piss-weak policies and a government at war with its own environment. Despite a few recent wins in marine conservation, Australia has a dreadful track record.

Now in another monumental demonstration of stupidity, corruption and colonial-era attitudes toward native wildlife, Western Australia has outdone itself by sneaking through legislation to extend its so-called ‘Barrier Fence’ in an effort to isolate its marginal farmland from dingoes, emus and other ‘nuisance’ species.

As I and several others have pointed out before, the mere existence of the record-breaking dingo fence is not only counter-productive, it is expensive and utterly archaic. It should be torn down entirely.

Instead, the Western Australian government wants to extend the national fence, and they’ve approved the plan it without going through any of the appropriate checks in the system. Its environmental impacts have not been adequately assessed, nor has the public been given the opportunity to oppose the plans. In my view, the people responsible for this act should go to gaol.

In a recent paper led by Keith Bradby entitled Ecological connectivity or Barrier Fence? Critical choices on the agricultural margins of Western Australia, we show how the Western Australia state government has not followed any of its own environmental legislation and rushed through these idiotic proposals. If you do not subscribe to Ecological Management and Restoration, you can obtain a copy of the paper by e-mailing Keith or me. Read the rest of this entry »





Western Australia’s moronic shark cull

4 07 2014

another stupid politicianA major media release today coordinated by Jessica Meeuwig in Western Australia makes the (obvious) point that there’s no biological justification to cull sharks.

301 Australian and International Scientists experts have today provided their submission to the Western Australia Environmental Protection Authority (EPA), rejecting the scientific grounds for the proposed three-year drum-line programme.

Coordinating scientist, Professor Jessica Meeuwig from the University of Western Australia said:

“To have over 300 researchers, including some of the world’s top shark specialists and marine ecologists, all strongly agreeing that there is no scientific basis for the lethal drum-line programme, tells you how unjustified the government’s proposal is. If the EPA and the Federal Minister for the Environment are using science for decisions, the drum-line proposal should not be approved.”

The experts agree that the proposal presents no evidence that the lethal drum-line programme, as implemented, will improve ocean safety. It ignores evidence from other hook-based programs in Hawaii and Queensland that have been shown to be ineffective in reducing shark attacks on humans.

Dr. Christopher Neff from the University of Sydney stated:

“There is no evidence that drum lines reduce shark bites. The Western Australia EPA now faces a question of science versus politics with global implications because it is considering establishing a new international norm that would allow for the killing of protected white sharks.”

The drum lines are ineffective and indiscriminate, with 78% of the sharks captured not considered ‘threatening’ to humans. Yet, scientifically supported, non-lethal alternatives such as the South African ‘Shark Spotter’ and Brazil’s ‘Tag and Remove’ programmes are not adequately assessed as viable options for Western Australia. Read the rest of this entry »





Eye on the taiga

24 03 2014

boreal damageDun! Dun, dun, dun! Dun, dun, dun! Dun, dun, daaaaah!

I’ve waited nearly two years to do that, with possibly our best title yet for a peer-reviewed paper: Eye on the taiga: removing global policy impediments to safeguard the boreal forest (recently published online in Conservation Letters).

Of course, the paper has nothing to do with cheesy Eighties music, underdog boxers or even tigers, but it does highlight an important oversight in world carbon politics. The boreal forest (also known as taiga from the Russian) spans much of the land mass of the Northern Hemisphere and represents approximately one quarter of the entire planet’s forests. As a result, this massive forest contains more than 35% of all terrestrially bound carbon (below and above ground). One doesn’t require much more information to come to the conclusion that this massive second lung of the planet (considering the Amazon the first lung) is a vital component of the world’s carbon cycle, and temperate biodiversity.

The boreal forest has been largely expanding since the retreat of the glaciers following the Last Glacial Maximum about 20,000 years ago, which means that its slow progression northward has produced a net carbon sink (i.e., it takes up more atmospheric carbon that it releases from decomposition). However, recent evidence suggests that due to a combination of increased deforestation, fire from both human encroachment and climate change, mass outbreaks of tree-killing insects and permafrost melting, the boreal forest is tipping towards becoming a net carbon source (i.e., emitting more carbon into the atmosphere than it takes up from photosynthesis). This is not a good thing for the world’s carbon cycle, because it means yet another positive feedback that will exacerbate the rapid warming of the planet. 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 »





Translocations: keep it in the family

31 10 2013
CB_Translocations_Photo
Prairie dogs (Cynomys spp.) comprise 5 species native to North American grasslands. Rather than a ‘dog’ (‘perrito’ or ‘little dog’ in Spanish), this animal is a squirrel (Sciuridae) adapted to ground life. In particular, black-tailed prairie dogs (C. ludovicianus) inhabit the plains between the Frenchman River in Canada and the Mexican stretches of the Sonoran and Chihuahuan deserts. Individuals have a maximum length of 40 cm and weigh up to 2 kg. The global population is currently estimated at some 18 million individuals over an area that has waned by 90% relative to historical ranges. The species is IUCN ‘Least Concern’ and shows a global ‘decreasing’ trend as a result of ongoing habitat loss and fragmentation due to urban development and farming, and susceptibility to Yersinia pestis – a bacteria that causes plague in prairie dogs and other mammals including humans.Colonies, known as ‘coteries’ (from French), are made of several family clans that live in contiguous territories. Clans include one or two males, and several females and juveniles [7]. Females show strong philopatry, while males are the ones that colonise new territories, or mingle with existing clans. Such dispersion pattern, along with daughters deliberately avoiding incest, minimises inbreeding [8]. Burrows consist of >10-m tunnels in which temperatures remain between 5 and 25 ºC irrespective of above-ground temperatures. Prairie dogs are genuine landscape architects with their network of burrows largely increasing edaphic, botanic and zoological diversity [9]. The pic shows two black prairie dogs in Wind Cave National Park (South Dakota, USA) (courtesy of Lisa Savage).

If you have lived in different suburbs, cities or even countries, you will be well aware that changing residence feels very different whether you do it on your own or with someone else. In the latter case, you might have to share tasks, and key decisions have to be made on the basis of everybody’s needs. The situation is analogous when managers decide to move a group of animals or plants from one place to another – so-called translocation.

Translocations involve human-assisted movements of organisms into an area (i) that holds an existing population of the same species (re-stocking), or (ii) where the species has been extirpated (re-introduction) or (iii) is outside its historical distribution (introduction) [1] – this terminology follows 1993 IUCN’s Criteria [1, 3], but is unstable, e.g., see [2]. The rationale behind translocations has obvious merits (e.g., to promote population growth following overharvesting, attenuate human-predator conflicts, rescue endangered species) [2]. However, translocations are complex and have a long record of failed attempts in the history of conservation biology, so the resulting waste of resources has prompted a recent re-appraisal of methods [1-3].

Debra Shier investigated the nuisances of a translocation of a social species such as the black-tailed prairie dog (Cynomys ludovicianus) [4]. Shier tagged, sexed and determined (via capture-recapture and field observations) membership to identified family clans in 973 individuals from Vermejo Park (New Mexico, USA). She then introduced clans to ten dog-free sites with soil quality and vegetation cover akin to the historical distribution of the species. In five of those sites, Shier translocated family clans (4 to 7 individuals per clan) and in the other five sites she freed clans made up of members being picked up randomly (1 male, 2 females, 2 juveniles). During a period of 9-10 months after translocation, Shier monitored the behaviour of females and ultimately re-captured all introduced individuals. She found that 50% of the dogs had survived translocation, and assumed that the remainder had died since individuals rarely disperse more than three km from their natal area, and aerial surveys spotted no dogs in a four-km perimeter around the point of release.

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 »





Shrinking global range projected for the world’s largest fish

7 08 2013
© W. Osborn (AIMS)

© W. Osborn (AIMS)

My recently finished PhD student, Ana Sequeira, has not only just had a superb paper just accepted in Global Change Biology, she’s recently been offered (and accepted) a postdoctoral position based at the University of Western Australia‘s Oceans Institute (in partnership with AIMS and CSIRO). As any supervisor, I’m certainly pleased when a student completes her PhD, but my pride as an academic papa truly soars when she gets her first job. Well done, Ana. This post by Ana is about her latest paper.

Following our previous whale shark work (see herehereherehere, here, here and here), especially the recent review where we inferred global connectivity and suggest possible pathways for their migration, we have now gone a step further and modelled the habitat suitability for the species at at global scale. This paper sets a nice scene regarding current habitat suitability, which also demonstrates the potential connectivity pathways we hypothesised previously. But the paper goes much further; we extend our predictions to a future scenario for 2070 when water temperatures are expected to increase on average by 2 °C.

Sequeira et al_GCB_Figure 3

Global predictions of current seasonal habitat suitability for whale sharks. Black triangles indicate known aggregation locations. Solid line delineates areas where habitat suitability > 0.1 was predicted.

Regarding the current range of whale sharks (i.e., its currently suitable habitat), we already know that whale sharks span latitudes between about 35 º North to South. We also know that this geographical range has been exceeded on several occasions. What we did not know was whether conditions were suitable enough for whale sharks to cross from the Indian Ocean to the Atlantic Ocean – in other words, whether they could travel between ocean basins south of South Africa. Our global model results demonstrate that suitable habitat in this region does exist at least during the summer, thus supporting our hypotheses regarding global connectivity!

It’s true that the extensive dataset we used (30 years’ worth of whale shark sightings collected by tuna purse seiners in the three major oceans – data provided by the IRD, IOTC and SPC) has many caveats (as do all opportunistically collected data), but we went to great trouble to deal with them in this paper (you can request a copy here or access it directly here). And the overall result: the current global habitat suitability for whale sharks does agree well with current locations of whale shark occurrence, with the exception of the Eastern Pacific for where we did not have enough data to validate. Read the rest of this entry »





Our national parks must be more than playgrounds or paddocks

24 05 2013

Convo TweetsIt’s interesting when a semi-random tweet by a colleague ends up mobilising a small army of scientists to get pissed off enough to co-write an article. Euan Ritchie of Deakin University started it off, and quickly recruited me, Mick McCarthy, David Watson, Ian Lunt, Hugh Possingham, Bill Laurance and Emma Johnston to put together the article. It’s a hugely important topic, so I hope it generates a lot of discussion and finally, some bloody action to stop the rapid destruction of this country’s national parks system.

Note: Published simultaneously on The Conversation.

It’s make or break time for Australia’s national parks.

National parks on land and in the ocean are dying a death of a thousand cuts, in the form of bullets, hooks, hotels, logging concessions and grazing licences. It’s been an extraordinary last few months, with various governments in eastern states proposing new uses for these critically important areas.

Australia’s first “National Park”, established in 1879, was akin to a glorified country club. Now called the “Royal National Park” on the outskirts of Sydney, it was created as a recreational escape for Sydney-siders, with ornamental plantations, a zoo, race courses, artillery ranges, livestock paddocks, deer farms, logging leases and mines.

Australians since realised that national parks should focus on protecting the species and natural landscapes they contain. However, we are now in danger of regressing to the misguided ideals of the 19th Century.

Parks under attack

In Victoria, new rules will allow developers to build hotels and other ventures in national parks. In New South Wales, legislation has been introduced to allow recreational shooting in national parks, and there is pressure to log these areas too. Read the rest of this entry »





A carbon economy can help save our species too

20 05 2013

money treeWe sent out this media release the other day, but it had pretty poor pick-up (are people sick of the carbon price wars?). Anyway, I thought it prudent to reprint here on CB.com.

Will Australia’s biodiversity benefit from the new carbon economy designed to reduce greenhouse gas emissions? Or will bio-‘perversities’ win the day?

“Cautious optimism” was the conclusion of Professor Corey Bradshaw, Director of Ecological Modelling at the University of Adelaide’s Environment Institute. He is lead author of a new paper published in the journal of Biological Conservation which reviewed the likely consequences of a carbon economy on conservation of Australian biodiversity.

“In most circumstances these two very important goals for Australia’s future – greenhouse gas emissions reduction and biodiversity conservation – are not mutually exclusive and could even boost each other,” Professor Bradshaw says.

“There are, however, many potential negative biodiversity outcomes if land management is not done with biodiversity in mind from the outset.”

The paper was contributed to by 30 Australian scientists from different backgrounds. They reviewed six areas where Australia’s Carbon Farming Initiative could have the greatest impact on biodiversity: environmental plantings; policies and practices to deal with native regrowth; fire management; agricultural practices; and feral animal control.

“The largest biodiversity ‘bang for our buck’ is likely to come from tree plantings,” says Professor Bradshaw. “But there are some potential and frightening ‘bioperversities’ as well. For example, we need to be careful not to plant just the fastest-growing, simplest and non-native species only to ‘farm’ carbon.

“Carbon plantings will only have real biodiversity value if they comprise appropriate native tree species and provide suitable habitats and resources for valued fauna. Such plantings could however risk severely altering local hydrology and reducing water availability.”

Professor Bradshaw says carefully managing regrowth of once-cleared areas could also produce a large carbon-sequestration and biodiversity benefit simultaneously. And carbon price-based modifications to agriculture that would benefit biodiversity included reductions in tillage frequency, livestock densities and fertiliser use, and retention and regeneration of native shrubs. Read the rest of this entry »





Crying ‘wolf’ overlooks the foxes: challenging ‘planetary tipping points’

28 02 2013

tipping pointToday, a paper by my colleague, Barry Brook, appeared online in Trends in Ecology and Evolution. It’s bound to turn a few heads.

Let’s not get distracted by the title of the post, or the potential for a false controversy. It’s important to be clear that the planet is indeed ill, and it’s largely due to us. Species are going extinct faster than the would have otherwise. The planet’s climate system is being severely disrupted, so is the carbon cycle. Ecosystem services are on the decline.

But – and it’s a big ‘but’ – we have to be wary of claiming the end of the world as we know it or people will shut down and continue blindly with their growth and consumption obsession. We as scientists also have to be extremely careful not to pull concepts and numbers out of our bums without empirical support.

Specifically, I’m referring to the latest ‘craze’ in environmental science writing – the idea of ‘planetary tipping points‘ and the related ‘planetary boundaries‘. It’s really the stuff of Hollywood disaster blockbusters – the world suddenly shifts into a new ‘state’ where some major aspect of how the world functions does an immediate about-face. Read the rest of this entry »





Whither goest the biggest fish?

7 02 2013
© W Osborn (AIMS)

© W Osborn (AIMS)

Well, since my own institute beat me to the punch on announcing our latest whale shark paper (really, far too keen, ladies & gents), I thought I’d better follow up with a post of my own.

We’ve mentioned our previous whale shark research before (see here and here for previous posts, and see the end of this post for a full list of our whale shark publications), but this is a lovely extension of that work by my recently completed PhD student, Ana Sequeira.

Her latest contribution, Inferred global connectivity of whale shark Rhincodon typus populations just published online in Journal of Fish Biology, describes what a lot of whale shark punters & researchers alike have suspected for a long time – global connectivity of all the oceans’ whale shark populations. The problem hasn’t been a lack of ‘evidence’ for this per se; there is now sufficient evidence from genetic studies that at least on the generational scale (a single generation could be up to 37 years long), populations among the major ocean basins are connected via migration (Castro et al. 2007Schmidt et al. 2009). The problem instead is that no one has ever observed a shark voyage between ocean basins, nor has anyone really suggested how and over what time scales this (must) happen.

Until now, that is. Read the rest of this entry »





Translocations: the genetic rescue paradox

14 01 2013

helphindranceHarvesting and habitat alteration reduce many populations to just a few individuals, and then often extinction. A widely recommended conservation action is to supplement those populations with new individuals translocated from other regions. However, crossing local and foreign genes can worsen the prospects of recovery.

We are all hybrids or combinations of other people, experiences and things. Let’s think of teams (e.g., engineers, athletes, mushroom collectors). In team work, isolation from other team members might limit the appearance of innovative ideas, but the arrival of new (conflictive) individuals might in fact destroy group dynamics altogether. Chromosomes work much like this – too little or too much genetic variability among parents can break down the fitness of their descendants. These pernicious effects are known as ‘inbreeding depression‘ when they result from reproduction among related individuals, and ‘outbreeding depression‘ when parents are too genetically distant.

CB_OutbreedingDepression Photo
Location of the two USA sites providing spawners of largemouth bass for the experiments by Goldberg et al. (3): the Kaskaskia River (Mississipi Basin, Illinois) and the Big Cedar Lake (Great Lakes Basin, Wisconsin). Next to the map is shown an array of three of the 72-litre aquaria in an indoor environment under constant ambient temperature (25 ◦C), humidity (60%), and photoperiod (alternate 12 hours of light and darkness). Photo courtesy of T. Goldberg.

Recent studies have revised outbreeding depression in a variety of plants, invertebrates and vertebrates (1, 2). An example is Tony Goldberg’s experiments on largemouth bass (Micropterus salmoides), a freshwater fish native to North America. Since the 1990s, the USA populations have been hit by disease from a Ranavirus. Goldberg et al. (3) sampled healthy individuals from two freshwater bodies: the Mississipi River and the Great Lakes, and created two genetic lineages by having both populations isolated and reproducing in experimental ponds. Then, they inoculated the Ranavirus in a group of parents from each freshwater basin (generation P), and in the first (G1) and second (G2) generations of hybrids crossed from both basins. After 3 weeks in experimental aquaria, the proportion of survivors declined to nearly 30% in G2, and exceeded 80% in G1 and P. Clearly, crossing of different genetic lineages increased the susceptibility of this species to a pathogen, and the impact was most deleterious in G2. This investigation indicates that translocation of foreign individuals into a self-reproducing population can not only import diseases, but also weaken its descendants’ resistance to future epidemics.

A mechanism causing outbreeding depression occurs when hybridisation alters a gene that is only functional in combination with other genes. Immune systems are often regulated by these complexes of co-adapted genes (‘supergenes’) and their disruption is a potential candidate for the outbreeding depression reported by Goldberg et al. (3). Along with accentuating susceptibility to disease, outbreeding depression in animals and plants can cause a variety of deleterious effects such as dwarfism, low fertility, or shortened life span. Dick Frankham (one of our collaborators) has quantified that the probability of outbreeding depression increases when mixing takes place between (i) different species, (ii) conspecifics adapted to different habitats, (iii) conspecifics with fixed chromosomal differences, and (iv) populations free of genetic flow with other populations for more than 500 years (2).

A striking example supporting (some of) those criteria is the pink salmon (Oncorhynchus gorbuscha) from Auke Creek near Juneau (Alaska). The adults migrate from the Pacific to their native river where they spawn two years after birth, with the particularity that there are two strict broodlines that spawn in either even or odd year – that is, the same species in the same river, but with a lack of genetic flow between populations. In vitro mixture of the two broodlines and later release of hybrids in the wild have shown that the second generation of hybrids had nearly 50% higher mortality rates (i.e., failure to return to spawn following release) when born from crossings of parents from different broodlines than when broodlines were not mixed (4).

Read the rest of this entry »





To corridor, or not to corridor: size is the question

24 04 2012

I’ve just read a really interesting post by David Pannell from the University of Western Australia discussing the benefits (or lack thereof) of wildlife ‘corridors’. I’d like to elaborate on a few key issues, and introduce the most important aspect that really hasn’t been mentioned.

Some of you might be aware that the Australian Commonwealth Government has just released its Draft National Wildlife Corridors Plan for public comment, but many of you might not really know what a ‘corridor’ constitutes.

Wildlife or biodiversity ‘corridors’ have been around for a long time, at least in terms of proposals. The idea is fairly simple to conceive, but very difficult to implement in practice.

At least for as long as I’ve been in the conservation biology biz, ‘corridors’ have been proffered as one really good way to make broad-scale landscape restoration plausible and effective for (mainly) forest-dwelling species which have copped the worst of deforestation trends around Australia and the world. The idea is that because of intense habitat fragmentation, isolated patches of primary (or at least, reasonably intact secondary) forest can be linked by planting some sort of long corridor of similar habitat between them. Then, all the little creatures can merrily make their way back and forth between the patches, thus rescuing each other from extinction via migration. Read the rest of this entry »





Tentacles of destruction

5 04 2012

This last post before Easter is something I’ve thought more and more about over the last few years. I wouldn’t have given it much time in the past, but I’m now convinced roads are one of the humanity’s most destructive devices. Let me explain.

Before I had a good grasp of extinction dynamics, I wouldn’t have attributed much import to the role of roads in conservation. I mean, really, a little road here and there (ok, even a major motorway) couldn’t possibly be a problem? It’s mostly habitat destruction itself, right?

Not exactly. With our work on extinction synergies, I eventually came to realise that roads are some of the first portals to the devastation to come. Read the rest of this entry »





Gone with the birds

1 09 2011

ebaumsworld.com

Another great post by Salvador Herrando-Pérez.

Through each new species, evolution assembles a unique combination of genes. Ever since living forms have populated our planet (> 3 billion years), the number of combinations is incalculable. That is why evolution resembles a cocktail shaker. Contemporaneous biogeographers look for order in that shaker to explain the history of life, as much as historians look for monarchs and revolutions in a library to explain the history of humanity.

The ethnic diversity of our suburb, village or city obeys factors of different temporal extent. Recent factors such as wealth, politics (war, segregation), culture (tradition, religion), and technology (airplanes, bridges, tunnels) determine racial migration, mixing and extinction. On the other hand, pre-historical factors express the expansion of the earliest hominids from Africa to the other continents – what makes a bantu ‘bantu’, or an inuit ‘inuit’.

Present ecological conditions and the macro-evolutionary past stock the elements by which biogeography attempts to understand the mechanisms shaping the spatial distribution of species, e.g., why kangaroos are restricted to Oceania, or why you could believe you were in Spain while strolling through a Greek forest. Read the rest of this entry »





Species’ Ability to Forestall Extinction – AudioBoo

8 04 2011

Here’s a little interview I just did on the SAFE index with ABC AM:

Not a bad job, really.

And here’s another one from Radio New Zealand:

CJA Bradshaw








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