A microscopic predator-prey chase

In terms of behaviour, animals have plants beat – though some would argue that plants have their own brand of intelligence.

Not all photosynthesizing beasts are firmly planted, though, and many that live in the water can move. Aquatic algae, for instance, often have whip-like structures (called cilia and flagella) that they can use to propel themselves along in the water. Some land plants also produce flagellated sperm that can move on their own volition.

H. akashiwo

A single-celled marine algae with flagella for getting around. From Wikimedia.

In the ocean, the ability to move can be beneficial, allowing algal cells to find food or move to a suitable environment. Motile cells can also avoid their predators by swimming away – something land plants definitely cannot do. Swimming algae incredibly slow, topping out at about half a centimetre per minute – but a new study suggests that the slow race between algae and their predators might be responsible for a far bigger, more dangerous phenomenon.

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Neanderthals were into birds

Well, into their feathers anyway. Thanks to a new study out this week, we now have paleontological proof that Neanderthals collected birds for more than just food. They probably used bird feathers for decoration – just like we do – suggesting that we aren’t the only hominid species to have developed an artistic culture1.

The research team – led by Clive Finlayson – used a combination of archaeological and paleontological evidence from several different sites where Neanderthals lived during the Paleolithic, ranging from Gibraltar in southern Spain to sites in the near East. For each site, the researchers tallied up the number of different bird species found in the fossil record at the same time and place as the Neanderthals, and they discovered that certain species were most frequent. The most common species were raptors (like vultures, kites and golden eagles) and corvids (like crows and choughs). Crucially, the researchers found that the remains of these particular species are far more abundant at the Neanderthal dwellings than they are at other paleontological sites – suggesting that the bird bones were there for a reason.

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Innovative, naturally

bluegill sunfish field work

Chandra Rodgers sampling bluegill sunfish on Lake Opinicon.

This spring I had the opportunity to write a feature article on the Queen’s University Biological Station, a site just north of Kingston where researchers have a long history of major scientific breakthroughs involving modest Ontario wildlife. Several of these discoveries have proved to be as useful as they are compelling. The story was published in the Kingston Whig Standard, and on the web through the Queen’s Alumni Review and InnovationCanada.ca. Funding for photography was provided by the CFI’s 2011 Emerging Science Journalists Award.

Talking to scientists about their research was by far the best part of this project – much more fun than I expected! And even the toughest interviews were a gold mine of ideas. Thanks to everyone who participated. The full story is posted below…

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Life imitates [filmmaking] art

Congratulations to Myra Burrell – her peacockumentary has been short-listed for the Animal Behavior Society’s film festival!

Myra, a veteran of the natural history film program at the University of Otago in New Zealand, traveled to California with me in 2010. She helped with peacock field work, capturing more females than anyone thought possible. Somehow, in the meantime, she made a movie about the birds. It’s a short film that gives you an idea about what happens on a peacock lek, from the hen’s point of view.

It’s quite an honour to be among the 6 films selected for festival screening, since they must get on the order of ~100 applicants. If Myra wins, it would be oddly fitting: a wildlife film straight out of a park that moonlights as a real Hollywood set.

You can watch “Hen’s Quest” here.

The best parts? I love the music and Myra’s cinematography. I contributed writing (including the title!) and did the artwork; Brian McGirr turned my map drawing into a fantastic animation. Good luck, Myra!

To save trees, major rethink is needed

When you stop to think about it, few things are weirder than a tree. Like us, they’re largish organisms made up of many cells, each with a central nucleus – but we have little else in common. Plants diverged from our early ancestors well before there was anything bigger than a single cell around. They split from the animal lineage even before fungi, which leads to a shocking conclusion. That spot of mould in the vegetable drawer? It’s more closely related to you than the plants upon which you both depend.

Small wonder, then, that plants don’t live and die by the same rules as animals – but this could have dire implications. That’s the message of a new study by Jonathan Davies of McGill University, published in PLoS Biology. Davies and his international collaborators have shown that the factors causing extinction in plants are entirely unexpected, and the upshot is that the current IUCN Red List criteria for listing endangered species – which are based on animal studies – might be useless when it comes to plants.

Davies and his team used the latest the comprehensive Red List data for all flowering plant species in two locations: the United Kingdom and the South African Cape. The Cape is a biodiversity hotspot with thousands of endemic species: plants that evolved there, and that can be found nowhere else. The UK flora, in contrast, is made up of species from other regions that moved in after the retreat of Pleistocene glaciers.

Previous work has shown that among mammals, we are most likely to lose species with large body sizes and long generation times – giant pandas and elephants are classic examples. But according to the new analysis, plants break the mold. Davies and coauthors found that the kinds of plants most at risk in the UK are different from those at risk of extinction in the Cape, indicating that basic traits like size have nothing to do with it. Using a detailed evolutionary history of the Cape species, the team also found evidence that extinction risk in plants is tightly linked to mode of speciation: the Cape species most at risk tend to be ones from the younger, rapidly-evolving lineages.

This implies that in plants, extinction is pruning the tips of the evolutionary tree. The authors suggest an explanation: unlike animals, new plant species tend to arise from small isolated populations that are at the extremes of a much larger ancestral range. Thus, a new plant starts off with a limited distribution, and because range size is an important criteria for Red List risk, it is also highly vulnerable.

The team’s analysis of anthropogenic factors turned up an additional surprise. For the Cape flora, human-induced habitat changes such as urbanization and agriculture cannot explain extinction risk of local plants. In other words, there is no simple geographic correspondence between human activity and plant decline. As the authors put it, places like the South African Cape might therefore be both “cradles and graveyards of diversity”, regardless of human activities.

This study suggests that a major strategy revision is in order if we want to conserve the world’s plants – a group that we all depend upon for oxygen and energy. More generally, risk criteria for one taxonomic group cannot necessarily be applied to another, since the pathways to rarity may be as foreign as the species themselves.

Further Reading

Davies, J. T. et al. 2011. PLoS Biology: 9(5): e1000620.

Cuttlefish strike a pose for 3D camouflage

In the game of hide and seek, cuttlefish have the upper hand. These chameleons of the sea are astonishingly good at disappearing: they can instantaneously change the colour of their skin to blend in with the background, matching even the finicky details like the pattern of coloured rocks on the ocean floor.

Divers have long known that cuttlefish are masters of the 3D camouflage game, too, and new research from the Wood’s Hole Oceanographic Institute has revealed how they do it.

Alexandra Barbosa, a graduate student, and Dr. Roger Hanlon were interested in the way cuttlefish strike a pose when trying to hide. After encountering a predator, these octopus-like animals will flee among the corals, rocks and algae, and freeze with their arms contorted into shapes that mimic nearby objects – a feat made all the more impressive by the fact that cuttlefish arms can bend in any direction. Some birds and insects are also known to camouflage themselves with body posture, but few come close to cuttlefish in shape-shifting flexibility (see photos of cephalopod camouflage in the wild here).

To understand just how they do it, Barbosa and her colleagues in Dr. Hanlon’s lab presented captive cuttlefish with some highly unusual surroundings: jailbird stripes, in black and white. In response, the cuttlefish got theatrical, raising their arms roughly parallel to the angle of the stripes. And when the researchers shifted the angle of the background image, the cuttlefish stretched their arms into a new position in an attempt to stay hidden.

Cuttlefish posing on artificial backgrounds

Cuttlefish posing against different backgrounds. Modified from Barbosa et al. 2011 (see Figure 1).

Intriguingly, not all of the ten individuals tested were able to match the angle perfectly all of the time – but these quirks may not be surprising given that cuttlefish camouflage is so complex. After all, in nature cephalopods get to choose their own hiding places, a decision that might involve several different factors. According to the researchers, camouflaged cuttlefish are even known to gently wave their arms to match the movement of the underwater plants they are trying to mimic.

These results are a clear demonstration that cuttlefish use vision to guide their 3D camouflage, since the study animals matched a flat background image. Moreover, Barbosa and Hanlon have shown that shape-shifting cephalopods can easily handle scenarios that would never occur in the environment where these behaviours evolved, and adjust just as flexibly to this artificial environment as they do in their natural habitats.

Captive experiments like this are just the first step in understanding how cuttlefish use visual cues to hide, and some big questions remain. For instance, little is known about how cuttlefish can detect and match colours so well despite the fact that they are, in effect, colourblind – Hanlon has found that giant Australian cuttlefish can take on the colouration of rocks on the ocean floor even in the middle of the night.

These remarkable split-second decisions about where, and how, to hide might also help us understand something bigger. Strategic camouflage is just one aspect of the surprising intelligence of cuttlefish, which have the largest brains for a given body size of any invertebrate – these animals are also able to learn and communicate with one another at a level that rivals many land-based animals. It will be intriguing to see where hide and seek fits in to the history of cephalopod brain evolution.

Further Reading

Barbosa, A. et al. 2011. Proceedings of the Royal Society B. In press.

How I learned to respect the peahen

Written for the Los Angeles Arboretum.

Meep meep? More like “Honk honk!”

Arboretum regulars will no doubt recognize the call of a startled peahen, but you may not be aware of the clever ways they use it. Not that they try to boast or taunt the enemy, necessarily, but I’m starting to think that the birds at the Arboretum owe a lot to their version of the Road Runner’s call.

How do I know? Some background is in order here: I’m the tall blond woman who has been hanging around the Arboretum morning and night for the past few years, overdressed and hauling a camera, a pair of binoculars, some peanuts and, if I was lucky, a peacock. Working at the park each spring, I often wished I had more time to chat with visitors. But I was preoccupied, and the life of an ornithologist can sometimes feel like that of Wile E. Coyote on a bad day.

For the past four years, I’ve been chasing peafowl across the continent – from Arcadia in February to Winnipeg, Toronto and New York in May and June. Incidentally, the Bronx Zoo is the only place in North America that even comes close to the Arboretum in sheer number of peafowl. Three years into my PhD in biology, and I’ve spent literally hundreds of hours watching these birds.

You may be wondering what got me into this mess.

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Species of serendipity

Like most ideas, this one arrived in the shower. I needed to write a post for this week, but my list of topics was wearing thin and the weather is finally starting to get nice enough to distract me. Sure, I had a few promising ideas lined up, but they all need more time to develop. Plus I had a DVD to watch: a Nature of Things episode on serendipity in science due back at the library. Then it hit me – of course! I’ll watch the episode and then write about that.

Serendipity – supposedly one of the top ten most untranslatable words in the English language – was coined in the 1700s by Horace Walpole as a play on the tile of a Persian fairy tale. The Three Princes of Serendip takes place in Sri Lanka. It follows the adventures of three brothers exiled from the island by their father the king, in hopes that his sons might achieve a more worldly education. In the course of their travels, the princes go on to solve many mysteries – like unintentionally tracking down a lost camel on scant evidence – thanks to their sagacity and a series of lucky accidents.

Since Walpole, the word has taken on a close association with Eureka moments in science, starting with Archimedes’ famous bath. Supposedly, the ancient Greek mathematician solved the problem of measuring the volume of irregular objects after noticing how his own body displaced water in the tub.

Scientists have taken a great interest in tracking serendipity, perhaps because it seems to play a role in research success. Wikipedia has an extensive list of celebrated examples, from Viagra to chocolate chip cookies. Many have looked for ways to encourage this kind of scholarly luck. For instance, after his Nobel prize winning work on viruses, the molecular biologist Max Delbrück is perhaps best known for coming up with the principle of limited sloppiness: researchers should be careless enough that unexpected things can happen, but not so sloppy that they can’t reproduce them when they do. Alexander Fleming had this advantage when he discovered penicillin. He first noticed its antibiotic effects in a stack of dirty culture dishes that he hadn’t bothered to clean before leaving for summer vacation.

So how do people study something that is by definition rare and unusual? Psychology Today has summed up some of the latest research on luck, most of it based on surveys of people who claim to be especially serendipitous1. Not surprisingly, they are more competent, confident and willing to take risks than the rest of us. They are also more extroverted and less neurotic than most. Being born in the summer apparently helps as well – especially May.

Other advice might be more practical.

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Monkeys draw from memory

We’re a little bit closer to understanding what it’s like to be a monkey, and it’s thanks to the same technology that powers your smartphone: the touchscreen.

The latest victory for touchscreens is in the field of memory research. Scientists have been studying this ability in animals for decades – some birds, for example, are remarkably good at keeping track of the little details they use when foraging. Florida scrub jays collect thousands of acorns in the fall, hiding them as reserves to help get through the winter. Proof that scrub jays can keep track of multiple pieces of information about their caches – including the type of food, its perishability, and how long it ago it was stored – came from some clever experiments where jays learned to store worms and peanuts in sand-filled ice cube trays in the lab1. Rufous hummingbirds perform a similar feat. They can keep track of flowers on their daily foraging routes, including when the nectar for each one should be replenished, and time their visits accordingly. How do we know? Biologists taught hummingbirds in the Alberta Rockies to feed at artificial flowers that could be refilled on schedule2.

There is also a long history of research on the mental capacities of our closest animal relatives, primates. Rhesus macaque monkeys, a lab favourite used in countless studies of pharmacology and physiology, can easily keep track of a set of objects and spot the difference if you show them an altered version later on3. Not surprisingly, primates seem to have better memories than birds. Baboons can learn thousands of different photographic images and retain these memories for years – incredibly, when this particular study went to press, the baboons were up to 5000 and still hadn’t maxed out their capacity4.  Pigeons, on the other hand, hit a memory wall at roughly 1000 images4. These abilities might prove useful to primates like the chimpanzees living in the Taï National Park of Côte d’Ivoire, Africa. They make extensive use of their vast forest habitat, visiting hundreds of fruit trees that ripen on different schedules5. The Taï chimps can apparently remember where the especially productive trees are, and will often travel longer distances just to get there5.

But there is something missing from this research. It has to do with a subtle distinction in the way memory works: the difference between recognition and recall. Recognition is the ability to identify something because you’ve experienced it in the past. Recall, which can be more difficult, involves retrieving that memory on demand. Ben Basile and Rob Hampton liken it to the difference between a police lineup and talking to a criminal sketch artist. To recognize something is to see it and sense familiarity; to recollect is to create that experience in its absence.

So far all we have been able to study in animals is recognition. Without language, we can’t get them to describe their memories – until now, that is. Basile and Hampton, two scientists from the Yerkes National Primate Research Center in Atlanta, have figured out how to get monkeys to act like criminal sketch artists6.

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Elections are like peacocks

Both are loud, and both cause colourful flashy things to pop up on lawns everywhere. And much like elections, the peacock’s train is a costly endeavour. The species might be better off in terms of survival and abundance if they could just do away with those feathers. In terms of sheer waste, they remind me of the Green party pamphlets in our apartment building entrance way. They were stuffed blindly into all of the available mailboxes – which happen to be for street level businesses on our downtown block, not residents. Nice.

Peacocks and elections are both supposed to experience strong positive feedback effects. In politics, momentum can lead to rapid climbs in popularity. Sexual selection can be similar: as Ronald A. Fisher pointed out, exaggerated male traits can potentially evolve through a process of positive feedback. If enough females prefer the particular male trait initially, and the next generation inherits both the female preference and the exaggerated male trait, it can kick-start a runaway process of sexual selection to extremes.

Despite claims to the contrary, we don’t actually know whether Fisher’s runaway process contributed to peacock evolution. But it may be reasonable to assume that it played at least some role: positive feedback should set up easily so long as mate choice is not very costly for females2.

Thinking about peacocks gave me an insight that may have cured my allergy to all things political, at least temporarily. Not that I don’t care about the election – I do – but I can’t get over my frustration at the kinds of things that count as good arguments in the political sphere. Here’s an example: I’d like to learn more about the Green party, but they seem to support a whole lot of pseudoscientific nonsense. Apparently their health care platform includes homeopathy and various other forms of alternative medical quackery. How can we be sure they won’t apply the same less-than-rational approach to the environment? If only there could be “one true party”, I thought after the leaders’ debate – a notion that, briefly, made me wonder whether I might be a closet fascist.

This doubt came up again when I was reading an article in this week’s Nature about the effect of social media on research priorities. It focused on the controversial and totally unproven “liberation procedure” for MS – extremely popular in Canada but, oddly enough, nowhere else1. The article mentioned that Michael Ignatieff has stated his support for clinical trials of the treatment, despite the recommendation by a panel of CIHR experts that a clinical trial would be premature without further evidence from observational studies1. The authors of the Nature article – a group of doctors and medical researchers in Canada – ended up somewhere close to Ignatieff’s position nonetheless. They concluded that the benefits of a full-blown experimental trial might outweigh the costs if thousands of social media-influenced patients are travelling outside of the country to receive private treatment anyway, “exposing themselves to the risks and costs”1. In other words, popularity is an important – and rational – consideration when it comes to medical science.

I have two things to offer for election day. First, there is a good summary of where the major parties stand on science and research funding here. Some are a lot more rational than others.

On to the peacocks. Democratic elections, like sexually selected traits, are communal illusions. Money is another example. The more you accept them, the more you believe in them, the better they work.

References

  1. Chafe, R. et al. 2011. Nature 472: 410-411.
  2. Lande, R. 1981. PNAS 78: 3721-3725.