Inbreeding does matter

29 03 2010

I’ve been busy with Bill Laurance visiting the University of Adelaide over the last few days, and will be so over the next few as well (and Bill has promised us a guest post shortly), but I wanted to get a post in before the week got away on me.

I’ve come across what is probably the most succinct description of why inbreeding depression is an important aspect of extinctions in free-ranging species (see also previous posts here and here) by Mr. Conservation Genetics himself, Professor Richard Frankham.

Way back in the 1980s (oh, so long ago), Russ Lande produced a landmark paper in Science arguing that population demography was a far more important driver of extinctions than reduced genetic diversity per se. He stated:

“…demography may usually be of more immediate importance than population genetics in determining the minimum viable size of wild populations”

We now know, however, that genetics in fact DO matter, and no one could put it better than Dick Frankham in his latest commentary in Heredity.

I paraphrase some of his main points below:

  • Controversy broke out in the 1970 s when it was suggested that inbreeding was deleterious for captive wildlife, but Ralls and Ballou (1983) reported that 41/44 mammal populations had higher juvenile mortality among inbred than outbred individuals.
  • Crnokrak and Roff (1999) established that inbreeding depression occurred in 90 % of the datasets they examined, and was similarly deleterious across major plant and animal taxa.
  • They estimated that inbreeding depression in the wild has approximately seven times greater impact than in captivity.
  • It is unrealistic to omit inbreeding depression from population viability analysis models.
  • Lande’s contention was rejected when Spielman et al. (2004) found that genetic diversity in 170 threatened taxa was lower than in related non-threatened taxa

Lande might have been incorrect, but his contention spawned the entire modern discipline of conservation genetics. Dick sums up all this so much more eloquently than I’ve done here, so I encourage you to read his article.

CJA Bradshaw

ResearchBlogging.orgFrankham, R. (2009). Inbreeding in the wild really does matter Heredity, 104 (2), 124-124 DOI: 10.1038/hdy.2009.155

Lande, R. (1988). Genetics and demography in biological conservation Science, 241 (4872), 1455-1460 DOI: 10.1126/science.3420403

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Don’t miss Bill

25 03 2010

Yes, yes, I know I’ve posted only a little under two weeks ago that the venerable William (Bill) Laurance is coming to Adelaide, and anyone even remotely interested in biodiversity conservation would be a fool to miss his talks, and ra, ra, ra…

Well, you would be.

However, I don’t want anyone to miss this opportunity simply because of non-recognition. So I thought it prudent to remind people just how special this visit is, and what a researcher extraordinaire Bill really is. For those not necessarily following the trends in tropical conservation biology (probably not many in Adelaide, at least), you might not necessarily recognise his name.

So, I thought I’d give a little broadsheet of his achievements, Read the rest of this entry »





Classics: Extinction from Climate Change

22 03 2010

© A. Wong

Amidst the mildly annoying, yet functionally irrelevant sensationalism of climate change politics, conservation biologists are taking the problem seriously and attempting to predict (and prevent) extinctions arising from a rapidly heating planet (see BraveNewClimate.com‘s excellent summary here, as well as his general category of ‘ecological impacts of climate change‘).

This week’s Conservation Classic describes the first high-impact paper to signal just how bad it biodiversity could fare from climate change alone (ignoring, for the moment, synergies with other drivers of extinction).

From about the 1990s onward, conservation biologists had been accumulating a large number of case studies quantifying the extent to which species had shifted in their geographic ranges, phenology and behaviour in response to a rapidly warming planet (Parmesan & Yohe 2003). Read the rest of this entry »





Classics: Mesopredator Release

17 03 2010

© J. Short

Although popularised by Crooks & Soulé (1999), Soulé et al. (1988) first gave us the term that described how entire ecosystems can become unbalanced by a reduction of a higher trophic-level predator exerting so-called ‘top-down’ control on the abundance of species occupying lower trophic levels.

The idea had theoretical support in ecology (Wright et al. 1994; Litvaitis & Villafuerte 1996), but it was not until Soulé and colleagues described how the decline of dominant predators combines with habitat fragmentation to release top-down pressure on smaller predators, thereby increasing predation rates on prey lower down the trophic web.

Crooks & Soulé (1999) described an example where the decline in coyotes (Canis latrans) in combination with urbanisation-driven habitat fragmentation led to an increase in cat (Felis catus) densities and the subsequent decline in scrub-breeding birds. More recent examples attest to the importance of the mesopredator release phenomenon: Myers et al. (2007) described how the decline in large coastal shark species has allowed mesopredator cownose rays (Rhinoptera bonasus) to increase, leading to a reduction in commercially important shellfish densities; and Johnson et al. (2007) showed how dingoes (Canis lupus dingo) in Australia suppress populations of exotic predators such as cats and foxes, leading to more locally abundant populations of native marsupials (see previous post).

Conservation biologists have benefited from this knowledge because we’ve realised that top-order predators affect far more than their immediate prey. These examples really hit home how a fully functional community is required for ecosystem stability, so we should strive to preserve complete complements of communities, not just our favourite species.

CJA Bradshaw

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Bill Laurance coming to Adelaide

13 03 2010

We’ve got a real treat for biodiversity buffs scheduled for the end of March. Eminent (Distinguished, Famous, Respected… the list goes on) Professor William (Bill) Laurance is briefly leaving his tropical world and coming south to the temperate climes of Adelaide to regale us with his fascinating biodiversity research career.

Bill is a leading conservation biologist who has worked internationally on many high-profile threats to tropical forests—in the Amazon, Central America, Africa, and Australasia. A highly prolific scientist, to date he has published five books and over 300 scientific articles. Bill has recently commenced a position as Distinguished Research Professor at James Cook University and is involved with the Smithsonian Tropical Research Institute in Panama. He also happens to be the bloke that blew the lid open on the devastating effects of tropical fragmentation in the Amazon with some of the best long-term experiments ever done in conservation biology.

I’m personally very pleased for several reasons: (1) Although I have never met Bill in person yet, I’ve recently co-authored two papers with him (Wash and spin cycle threats to tropical biodiversity and Improving the performance of the Roundtable on Sustainable Palm Oil for nature conservation) and I’m keen to meet the man behind the pen; (2) we have had many email discussions (some of them rather heated!), so I’m keen to flesh some of these out over a nice glass of South Australian Shiraz; (3) he’s been a keen supporter of my work for years, and has given me many opportunities to get my research noticed; and (4) it’s high time to met one of ConservationBytes.com Conservation Scholars.

Bill has recently shifted shop from Panama (Smithsonian Tropical Research Institute) to Australia’s own James Cook University, and so we at the Environment Institute thought we should take advantage of his geographical disorientation and bring him down south for a while. But he’s going to have to sing for his supper, so he’s kindly agreed to give three talks in 3 days from 29-31 March 2010.

His first talk (on Monday 29 March) will be an in-house Environment Institute seminar, but the second two will be public events that I urge anyone remotely interested in biodiversity conservation research to attend. In fact, his Tuesday 30 March presentation (18.00-20.00 Napier G03, University of Adelaide) is even more generic than that, and word on the street is it is highly entertaining and extremely well attended wherever Bill’s is gracious enough to give it:

Amplify Your Voice: Keys to Having a Prolific Scientific Career (and Bill would know).

This will include (1) How to be more prolific: strategies for writing and publishing scientific papers and (2) Further ways to maximise your scientific impact – interacting with the popular media and how to promote yourself. Each topic will run for 50 minutes and will include 10 minutes for audience questions. A tea and coffee break will be held between sessions. Book here.

His second public talk on Wednesday 31 March (18.00-19.30 Napier 102, University of Adelaide) will be:

Diagnosis Critical | The lungs of our Planet

Here he will be discussing how the forests of our world are in crisis. Our drive for continued economic growth has had devastating consequences for the world’s ecosystems that provide critical human services. Our forests are a haven for countless plant and animal species that form the basis of ecological services, these services are the biological mechanisms that make the world our home. Book here.

So, if you have a couple of free nights at the end of the month and are in Adelaide, I strongly recommend you come out and see Bill do his thing.

CJA Bradshaw

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Global pollinator declines

11 03 2010

Mention anything about ecosystem services – those ecological functions arising from the interactions between species that provide some benefit (source of food/clean water, health, etc.) to humanity1 – and one of the most cited examples is pollination.

It’s really a no-brainer, hence its popularity as an example. Pollinators (mainly insects, but birds, bats and other assorted species too) don’t exist to pollinate plants; rather, their principal source of food acquisition happens to spread around the gametes of the plants they regularly visit. Evolution has favoured the dependence of species in such ways because the mutualism benefits all involved, and in some cases, this dependence has become obligate. So when the habitats that pollinators need to survive are reduced or destroyed, inevitably their population sizes decline and the plants on which they feed lose their main sources of gene-spreading.

So what? Well, about 80 % of all wild plant species require insect pollinators for fruit and seed set, and about 75 % of all human crops require pollination by insects (mostly bees). So it’s pretty frightening to consider that although our global population is at 6.8 billion and growing rapidly, our main food pollinators (bees) are declining globally (see also previous post on bee declines). Indeed, domestic honey bee stocks have declined in the USA by 59 % since 1947 and in Europe by 25 % since 1985. Scared yet?

Another thing people don’t tend to get is that a bee cannot live on rapeseed alone. Most pollinators require intact forests to complete many of their other life history requirements (breeding, shelter, etc.) and merely forage occasionally in crop lands. Cut down all the adjacent bush, and your crops will suffer accordingly.

These, and other titbits to keep you awake at night and worry about what your grandchildren might eat are highlighted in a recent review in Trends in Ecology and Evolution by Potts and colleagues entitled Global pollinator declines: trends, impacts and drivers.

What’s driving all this loss? Several things, but it’s mainly due to ‘land-use change’ (a bullshit word people use generally to mean habitat loss, fragmentation and degradation). However, invasive species competition, pathogens and parasites, and climate change (and the synergies amongst all of these) are all contributing.

It always amazes me when people ask me why biodiversity is important. Despite the overwhelming knowledge we’ve accumulated about how functioning ecosystems make the planet liveable, despite it just being plainly stupid to think that humans are somehow removed from normal biological processes, and even with such in-your-face examples of global pollinator declines and the real, extremely worrying implication for food supplies, many people just don’t seem to get it. Every tree you cut down, every molecule of carbon dioxide you release, every drop of water you waste will punish you and your family directly for generations to come. How much more self-evident can you get?

Humanity seems to have a very poorly developed sense of self-preservation.

CJA Bradshaw

1It’s amazingly arrogant and anthropocentric to think of anything in ecosystems as ‘providing benefits to humanity’. After all, we’re just another species in a complex array of species within ecosystems – we just happen to be one of the numerically dominant ones, excel at ecosystem ‘engineering’ and as far as we know, are the only (semi-) sentient of the biologicals. Although the concept of ecosystem services is, I think, an essential abstraction to place emphasis on the importance of biodiversity conservation to the biodiversity ignorant, it does rub me a little the wrong way. It’s almost ascribing some sort of illogical religious perspective that the Earth was placed in its current form for our eventual benefit. We might be a fairly new species in geological time scales, but don’t think of ecosystems as mere provisions for our well-being.

ResearchBlogging.orgPotts, S., Biesmeijer, J., Kremen, C., Neumann, P., Schweiger, O., & Kunin, W. (2010). Global pollinator declines: trends, impacts and drivers Trends in Ecology & Evolution DOI: 10.1016/j.tree.2010.01.007

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Scopus Young Researcher of the Year Awards

7 03 2010

Peter Love & Corey Bradshaw. © A. Harvey

Last week I tweeted a few times about an award I was lucky enough to win – the inaugural Scopus Young Researcher of the Year Award (in the Life Sciences and Biological Sciences category). The awards are supported by Elsevier, Scopus and Universities Australia. I just managed to get a hold of some photos from the award ceremony, so a little post is justified.

It was a fun night at Parliament House in Canberra in front of a very prestigious crowd – most of the Vice Chancellors of Australian universities were present, along with many other distinguished guests. A little daunting, but the reception was very warm indeed.

After meeting the welcoming and congratulatory Elsevier/Scopus team during a pre-dinner reception, the other category winners (Ben Eggleton, Peter Love, Dan Li and Prash Sanders) and I were then escorted to the main event at Parliament House. Bernie Hobbs of ABC Science acted as master of ceremonies, and Senator Kim Carr presented the awards with Y. S. Chi of Elsevier. Prash and I were honoured to sit at the same table with the University of Adelaide’s Vice Chancellor, Professor James McWha.

MC Bernie Hobbs. © A. Harvey

Thanks again to all those who supported my bid at the University of Adelaide and SARDI. Special thanks to Mike Young who nominated me, Barry Brook and Navjot Sodhi who provided reference letters, and K. Wertz for putting the finishing touches on the application.

The Higher Education supplement of the Australian published a few articles about the winners, and I reproduce the one describing my award and research below (article by C. Jones):

SHOOTERS in low-flying helicopters take out feral buffalo, horses and pigs that are wreaking havoc on Kakadu National Park.

There are no bullets and blood, however, as these are not real shooters and animals but silicon ones. They are cyber-entities, represented by numbers, generated in a computer model by mathematical ecologist Corey Bradshaw and his colleagues.

Land managers will be able to use the model to test scenarios in a virtual Kakadu National Park to work out the cheapest and best culling programs to limit the damage from the pests.

The mastery early in his career of mathematical modelling such as the Kakadu computer code has put Bradshaw at the forefront of conservation biology.

In naming him the Scopus young researcher of the year in the life sciences and biological sciences category, the judging panel says his modelling work has added “significant new perspectives and rigour” to his field.

Bradshaw grew up in western Canada. His interest in conservation was piqued when he ranged the Rocky Mountains of British Columbia with his father, who was a game trapper.

He later turned a knowledge of ecology that underpinned “killing things” to saving endangered species.

He obtained a bachelor of ecology from the University of Montreal in 1992. Research as part of a masters degree at the University of Alberta took him to northern Canada to study caribou. Later, he undertook a PhD in zoology at the University of Otago, Dunedin, with his research focusing on the population dynamics of fur seals.

The subjects of his fieldwork have ranged from the lowliest snails in Borneo, through penguins in Antarctica and frogs in Singapore, to Top End buffalo.

Some of his research is aimed at controlling pest species through an understanding of population dynamics. The goal of other work is to prevent extinctions of native species.

The research comes as the life sciences — once derided as the soft sciences — continue to harden up.

Like the so-called hard disciplines of physics and chemistry, biology is increasingly being structured by mathematics, and Bradshaw has been riding the wave.

The mathematics representing complex changes in populations as they boom, bust or stabilise in response to environmental factors is formidable. A paper on the Kakadu model, published recently in Methods in Ecology and Evolution, would not look out of place in a mathematics journal. It is full of equations, matrices and graphs.

“I realised the best thing I could do for my career was to get adept at mathematics,” he tells the HES. “You can’t do much of high value in conservation without it.

“The days of the natural historian walking around, casually drawing things and describing the reproductive structures of plants and animals are gone.

“We need to do the systematics as well, but the mathematics is a fundamental component of all biology now, especially ecology, because it’s such complex systems we’re dealing with.

“It’s chaos theory all the time.

“Trying to predict what an entire ecosystem is going to do gets very complicated very quickly, and mathematics is the only way to do it.”

Bradshaw’s Kakadu model divides the landscape into a grid. Equations in the model relate population size to demography for each element of the grid. Input demographic parameters include data obtained empirically through field studies: the age of individuals, the number of breeding females, and birth and mortality rates.

The program is run repeatedly, stepping forward in time, with the population size result of each run forming the initial condition of the next one.

“We can also do population viability analysis,” Bradshaw says. “We can make predictions on the probability that a population will go extinct within a certain period. It gives a window into the future.”

The work can deliver surprising results. Bradshaw’s team last year did an analysis for the federal government on the critically endangered grey nurse shark to find out the main factors in the species demise. The work showed that fishing was the biggest threat, not beach nets or a lack of protected areas, as previously suspected.

The results have influenced conservation policy, he says.

Other research suggests the Tasmanian devil, listed as endangered because of the devastating devil facial tumour disease that is ripping through populations, has recovered from big disease outbreaks before.

“We didn’t know that until we started looking at the demographic model,” Bradshaw says. “It is a scavenger, so it was probably exposed to a lot more diseases than your average animal.”

But he warns against complacency about the outbreak.

The modelling work has allowed him to make generalisations about the risk of extinction and that enables biodiversity managers to target their efforts.

“Five thousand is almost a magic number in conservation,” he says. “If you’re playing with less than that, you’re fighting a losing battle.”

The research also reveals which exotic species are likeliest to become invasive, knowledge valuable to biosecurity.

A consummate science communicator with a blog (ConservationBytes.com) and heavy community outreach schedule, Bradshaw is focusing on assessing the vulnerability of species to climate change.

And how do his models define Homo sapiens?

“They’re telling us that about 15 per cent of all the humans that ever lived are alive today,” he says. “That means that we are in the exponential phase of an invasion, much like rats on a new island or cockroaches in a new apartment.

“If we’re not careful, the very ecosystems that support our success will ensure our demise.”

CJA Bradshaw

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