To feed or to perish in an iceless world

1 02 2017
cb_climatechange2_polarbears_photo2

Emaciated female polar bear on drift ice in Hinlopen Strait (Svalbard, Norway), in July 2015 – courtesy of Kerstin Langenberger (www.arctic-dreams.com)

Evolution has designed polar bears to move, hunt and reproduce on a frozen and dynamic habitat that wanes and grows in thickness seasonally. But the modification of the annual cycle of Arctic ice due to global warming is triggering a trophic cascade, which already links polar bears to marine birds.

Popular and epicurean gastronomy claims that the best recipes should use seasonal veggies and fruits. Once upon a time, when there were no greenhouses, international trade routes, or as much frozen and canned food, our grandparents enjoyed what was available at the time. So in some years we had plenty of cherries, while during others we might have feasted on plums. Read the rest of this entry »





Rich and stable communities most vulnerable to change

16 08 2016

networkI’ve just read an interesting new study that was sent to me by the lead author, Giovanni Strona. Published the other day in Nature Communications, Strona & Lafferty’s article entitled Environmental change makes robust ecological networks fragile describes how ecological communities (≈ networks) become more susceptible to rapid environmental changes depending on how long they’ve had to evolve and develop under stable conditions.

Using the Avida Digital Evolution Platform (a free, open-source scientific software platform for doing virtual experiments with self-replicating and evolving computer programs), they programmed evolving host-parasite pairs in a virtual community to examine how co-extinction rate (i.e., extinctions arising in dependent species — in this case, parasites living off of hosts) varied as a function of the complexity of the interactions between species.

Starting from a single ancestor digital organism, the authors let evolve several artificial life communities for hundred thousands generation under different, stable environmental settings. Such communities included both free-living digital organisms and ‘parasite’ programs capable of stealing their hosts’ memory. Throughout generations, both hosts and parasites diversified, and their interactions became more complex. Read the rest of this entry »





Give way to the invader

25 01 2012

By weird coincidence, Salvador Herrando-Pérez (student blogger extra-ordinaire – see his previous posts on evolution, pollination, bird losses, taxonomic inflation, niche conservatism, historical biogeography, ecological traps and ocean giants) has produced a post this week expanding on the problem of roads. Also weirdly coincidental is that both Salva and I are in his home country of Spain this week.

Australia’s > 800,000-km road network would go 60 times around the equator of our planet. Confined to the boundaries of any one country, roads are a conspicuous component of the landscape, and shape the dispersion, survival and reproduction of many plants and animals in urban and remote areas.

Those who drive (or are driven by) will be familiar with the image of a crushed kangaroo on the roadside (a hedgehog in Europe), or the sticky mosaic of insects smashed against the windscreen after a high-speed run. Mortality by collision is one of the many effects that roads can have on the demography of organisms – including humans. Those effects encompass

  • physical alteration of terrestrial and aquatic habitats,
  • chemical pollution leakage during road construction and maintenance, and from asphalt compounds during storms,
  • alteration of animal behaviour (e.g., change in home range, or in patterns of flight or vocalisation),
  • access to remote areas by hunters, fishermen and gatherers in general, and
  • intense habitat fragmentation1-3.

However, some species get around those negative impacts by using the roads as pathways to new territories, thereby eluding barriers like seas, mountains, rivers, dense vegetation, or competition for vital resources with other species. Read the rest of this entry »





All that glitters is not gold – ecological traps

27 09 2011

Another corker from Salvador Herrando-Pérez:

Cinema fans know that choosing a movie by the newspaper’s commentary or the promotional poster might be a lottery. In the movie of nature, to confuse ‘the attractive’ with ‘the appropriate’ can compromise the life of an individual and its offspring, even to the extent of anticipating the extinction of an entire population or species.

Animals make daily choices about when, where or with whom to engage in basic activities like eating, hibernating, mating, migrating or resting. Those choices are often strongly tied to highly specific cues – e.g., air temperature, tree density, location of water, or smell of other individuals. And it happens to hair lice jumping from head to head among school kids, or to caribou forming their winter herds prior to the seasonal migration. All species, without exception, persist in nature because those ‘choices’ translate into survival or successful reproduction more often than do not. They are a kind of evolutionary memory imprinted in an organism’s genes and behaviour. However, sometimes the right choice (‘right’ meaning perceiving a cue for the role it actually has in the life cycle) places an individual in the worst of all possible situations. The environment cheats, ‘the attractive’ merely mimics ‘the appropriate’, and the individual fails to reproduce, starves, sickens, or even dies.

Figure 1. Water reservoirs tainted with fuel (see dark contours) in Kuwait following the Gulf War in the early 1990s. Overlaid pictures show the silhouettes of trapped odonates (right), vertebrates (top left) and invertebrates (bottom left) (Photos courtesy of Jochen Zeil).

At the mercy of mirages

During the Gulf War, the destruction of infrastructure for crude exploitation spilled large amounts of fuel in many water reservoirs over the desert landscape of Kuwait. A little later, Horváth and Zeil1 found agglomerations of dead insects (and a range of vertebrates) along the shores of these polluted reservoirs, and observed dragonflies drowning in their kamikaze attempt to spawn on the oily surface (Figure 1). This work stimulated further research whereby Horváth and his team in Budapest showed that odonates are attracted by light polarization at the surface of oiled water2 – hence ‘polarized light pollution’3. Not only that, they recorded insects struggling to spawn on or mate with riveting surfaces such as solar panels, asphalted roads, plastic bags or (creepy enough!) cemetery crypts4. It goes without saying: these insects are victims of a mirage.

Those habitats or features of the habitat that mislead an animal’s choice, often hampering the completion of its life cycle, are known as ‘ecological traps’ – in other words, the environmental cue is decoupled from the quality of the habitat it is meant to signal. Ecological traps were first described in the 1970s by Dwernychuk and Boag5. They found that ducks on the islands of Miquelon lake located their nests among those of seagulls despite the latter happily devoured their ducklings and eggs. When these islands emerged in the middle of last century, they were first colonized by common terns (Sterna hirundo). By defending their own nests ferociously from predators (mainly crows and magpies), the terns inadvertently shielded the nests of their ducky comrades. The Canadians hypothesized that when seagulls subsequently replace terns, the ducks continued to sense their new neighbours as a (now misleading) sign of protection. Read the rest of this entry »





Evolution of biodiversity: the hard evidence

25 09 2009

Just a plug for Richard Dawkins’ new book “The Greatest Show on Earth“. Hard to believe, but there are still billions of people who are blind to how life actually works, mainly from the intellectual blindfold of religion.

For more things Dawkins, visit http://richarddawkins.net/.





Charles Darwin, evolution and climate change denial

5 08 2009

DarwinThis week a mate of mine was conferred her degree at the University of Adelaide and she invited me along to the graduation ceremony. Although academic graduation ceremonies can be a bit long and involve a little too much applause (in my opinion), I was fortunate enough to listen to the excellent and inspiring welcoming speech made by the University of Adelaide’s Dean of Science, Professor Bob Hill.

Professor Hill is a world-renown expert in plant evolution, systematics and ecophysiology, and he gave a wonderful outline of the importance of Darwin’s legacy for today’s burgeoning problem solvers. I am reproducing Prof. Hill’s speech here (with his permission) as a gift to readers of ConservationBytes.com. I hope you enjoy it as much as I did.

Chancellor, Vice Chancellor, distinguished guests, members of staff, friends and family of graduates, and, most importantly of all, the new graduates, I am very pleased to have been asked to speak to you today, because 2009 marks one of the great anniversaries that we will see in our lifetimes. 200 years ago, on February 12th 1809, Charles Robert Darwin was born. To add to the auspicious nature of this year, 150 years ago, John Murray published the first edition of Darwin’s most famous book, titled On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life, better known to us all today as The Origin of Species.

I believe that from a modern perspective, Darwin was the most influential person who has ever lived. Darwin’s impact on how we think and work is much more profound than most people realise. He changed the entire way in which we go about living. Today, I want to talk to you briefly about how Darwin had this impact.

Darwin was a great observer and a great writer, but above all he was a great critical thinker. He became a scientist by a round about route, planning to be a doctor and a minister of religion along the way, although his passion was always natural history. He was not a great undergraduate student, but he benefited enormously from contact he had with University staff outside the formal classroom. His potential must have been obvious, because he was strongly recommended at a relatively young age, to take the position of naturalist and gentleman companion to Captain Robert Fitzroy on his famous five year voyage of the Beagle. Following this voyage, Darwin never physically left Britain again, but intellectually he roamed far and wide. Darwin was one of the great letter writers. He wrote thousands of letters to contacts all over the world, requesting specimens, data and opinions, and he worked relentlessly at analysing what he received back.

Over many years as a practising scientist I have met a lot of people with a passion for natural history, some of them trained scientists like Darwin, some of them gifted amateurs. There is a very obvious distinction between those with and without formal scientific training at a Tertiary level, but it took me a long time to work out what that distinction is. Let me digress slightly before I explain it.

In today’s terminology we talk a lot about graduate attributes. For some graduates, it is reasonably simple to define the kinds of attributes you expect them to have. I prefer engineers whose bridges don’t fall down, lawyers who keep me out of jail unnecessarily, accountants who can add up and doctors who do their best to keep me alive and healthy. However, the key attributes we expect of Science graduates are not so simple to define. You will all have one or more specialities where you have more knowledge than those who did not do the relevant courses, but if you are anything like I was when I was sitting out there waiting to graduate, you probably think you did what you had to do in order to pass your exams and you now think you have forgotten most of what you were taught. I can assure you that you haven’t, but I can also assure you that specific knowledge of a scientific subject is not the most important thing you have been taught here.

So what is that special something that separates out a professional scientist? It is the capacity for critical scientific thinking. You are now ready to work as professionals in many fields, and employers will actively seek to hire you because they know you have been trained here to apply a particular approach to problem solving. That approach is not easily obtained and has been taught to you in the most subtle way over the full breadth of what you have been exposed to during your time here. I suspect most of you don’t even know that you now have this skill, but you do. Darwin had it in the most sublime fashion.

When Darwin published the Origin of Species it was the culmination of decades of data gathering, backed up by meticulous analysis. Darwin never swayed from that rigorous approach, which strongly reflected the training he received as a student.

When you are exposed to a new problem, you will approach the solution in a similar way to Darwin. Let me consider the example of climate change. There is a remarkable parallel between the public reaction to the publication of the Origin of Species and the current public reaction to climate change. Darwin suffered a public backlash from people who were not ready to accept such a radical proposition as evolution by means of natural selection and this was reinforced by a significant number of professional scientists who were willing to speak out against him and his theory. As time went by, professional scientists were gradually won over by the weight of evidence, to the point where mainstream science no longer considers evolution as a theory but as scientific fact.

The reality of climate change and its potential impacts has not had a single champion like Darwin, but it has involved a similar slow accumulation of data and very careful analysis and critical thinking over the implications of what the data tell us. Initially, there were many scientists who spoke against the human-caused impact on climate change, but their number is diminishing. Most significantly, the critical analysis undertaken by thousands of mainstream scientists has gained broad political acceptance, despite the best efforts of special interest lobbyists. I suspect Darwin would be fascinated by the way this debate has developed.

Lobbyists who write stern words about how scientists as a whole are engaged in some conspiracy theory to alarm the general population simply do not understand or choose to ignore how scientists work. The world needs the critical and analytical thinking that scientists bring more than ever before. We live on a wonderful, resilient planet, that will, in the very long run, survive and thrive no matter what we do to it. But we are an extremely vulnerable species, and our survival in a manner we would consider as acceptable, is nowhere near as certain. That is the legacy of my generation to yours. I have faith that your generation will be wiser than mine has been, and I know that good science will lead the charge towards providing that wisdom.

Charles Darwin was the greatest scientist of all, and that is partly because he was a great observer and a great writer. But most of all, Darwin was the consummate critical thinker – he collected masses of data himself and from colleagues all over the world and he fashioned those data into the most relevant and elegant theory of all. I will conclude with a brief and well known passage from the first edition of the Origin of Species, which clearly demonstrates the power of Darwin’s writing:

Thus, from the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows. There is grandeur in this view of life, with its several powers having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.

I hope that the next Charles Darwin is sitting amongst you today. I know that at the very least I am standing in front of a group of people who have all the attributes necessary to be great contributors to the well-being of society and the planet. Be confident of your training and use your skills well. You have a grand tradition to uphold.

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