Science from the edge – part 2: chew and spit, scratch and sniff.

In the previous instalment of this series, which basically amounts to papers I would like to have written, I discussed the groundbreaking experiments by Carl Puke and Richard Taylor on the effects of explosions of various sorts on fish of various types. Although it was beyond the purview of the typical eco-evo research, it was at least eco-evo-explo. In this second instalment, I would like to move from auditory and visual extravagance to olfactory and gustatory revelation. Eco-evo-gusto?

The first classic paper I want to discuss is by Richard Wassersug, now of Dalhousie University and, at the time, of UC Berkeley. Perhaps the paper I will describe, published in The American Midland Naturalist in 1971, facilitated the upgrade in institution. Much science is motivated by simple observation, in this case the fact that tadpoles of many species seem common and conspicuous in tropical rainforests. Why aren’t they eaten by the numerous predators? Perhaps it is because they taste bad – but this wasn’t known for these tadpoles. Clearly this conundrum calls for a predation experiment where the predators are forced to eat the tadpoles and their judgement then passed on the experience. I will let the author take up the story of “On the comparative palatability of some dry-season tadpoles from Costa Rica.”

“The mock predator in this experiment was a sample of 11 students and faculty... The volunteers were two females and nine males aged 22 to 36 ...” One wonders how many students were in the course but did not volunteer for this particular experiment! And in the true spirit of good scientific practice, enough information is provided should one wish to replicate the study. “The standardized tasting procedure included several steps. A tadpole was rinsed in fresh water. The taster placed the tadpole into his or her mouth and held it for 10-20 sec without biting into it. Then the taster bit into the tail, breaking the skin and chewed lightly for 10-20 sec. For the last 10-20 sec the taster bit firmly and fully into the body of the tadpole. The participants were directed not to swallow the tadpoles but to spit them out and to rinse their mouths out at least twice with fresh water before proceeding to the next tadpole.”

Yum?

The first interesting result was that two of the nine volunteers in the experiment had to be eliminated as outliers because they either couldn’t taste anything or were outliers in finding the tadpoles less distasteful. Turns out they were smokers: why haven’t the smoking companies pick up on this benefit of their product? I can see the new label now: “Warning. This project may reduce your ability to find bad food distasteful.” A second important result was that the tadpoles differed in their palatability, with Bufo marinus (cane toad) being the worst and several other species sometimes being ranked reasonably high. However, it is hard to say more given that “No attempt has been made to put these data to any more rigorous statistical tests.”

If something like this can be done so effectively with taste – why not smell? Again, an observation sets the stage. Ever had to change the diaper of your sister’s or brother’s baby - nasty right? Indeed, much fouler than that of your own baby’s diaper, should you have one. If not, take my word for it. Or don’t, because we have a definitive objective controlled and replicated experiment. Writing in Evolution and Human Behavior in 2006, Case and coauthors asked mothers to smell the diapers of their own babies and other mother’s babies, with and without labels – with the labels sometimes correct and sometimes switched between babies. Turns out that other baby’s diapers are indeed more disgusting than your own baby’s – regardless of the label. The title says it all “My baby doesn’t smell as bad as yours: The plasticity of disgust.”

It would obviously be valuable to replicate these experiments. What about the taste of wet-season tadpoles? What about the aroma of your dog’s poop versus someone else’s dog’s poop? The opportunities seem limitless if not effortless. The truth is out there.

Dinosaurs to scientists: “Think fast!”

(A dispatch from Scott Carroll.)

I suppose few people grow up thinking much about evolution, though for decades kids have had dinosaurs, pterosaurs, wooly mammoths and saber-toothed cats actively released into the refuges of their imaginations. And imagine the thrill of early naturalists like Darwin, raised on different tales, who stumbled upon fossil skeletons of ancient titans and knew at once that the world has at times been a very different place from what the present otherwise suggests.

Fossil discoveries highlight ancient denizens of the evolutionary tree, but there is more immediate information at hand among the living: evolution-in-action. For a century, the blind spot of gradualism has led us to segregate evolution too neatly. Yes, air pollution can influence moth color frequencies, but we assume that’s a freak observation, and things quickly get back to normal. Sure, pathogens evolve to survive antimicrobial assault, but we assume they are a shifty peripheral class of small invisible things with their own rules.

But now we know, to the contrary, that the history of life is still being written, and that an evolutionary perspective is as relevant to our future as it is to our past.

Like a meteor gaining self-awareness at the moment of its impact, it is dawning within the collective consciousness of contemporary naturalists that industrial melanism was but the smoking gun of industrial selection, that microbes indeed ‘are us’, and that even the mighty trees may be light on their evolutionary feet. Anthropogenic evolution has left the farm (and the station), and accepted permanent positions in bathrooms, bus seats and hospitals around the world, near you, and on you (e.g., MRSA).

From equator to pole, metropolis to wilderness, 'refugee taxa' that are not disappearing altogether are persisting by adapting, and much of that adaptation is genetic. Other organisms too are evolving quickly to take advantage of new opportunities created by habitat disturbance, mass agriculture, increased human density, climate change, and other forces. Agricultural, medical and environmental systems thus consist of many 'moving targets' that are evolving their own 'solutions’, sometimes to the detriment of what we value, and sometimes quite the opposite. Meanwhile, what of species that are increasingly mismatched to their changing environments– what can evolutionary analyses tell us about the well-being and future of these adaptive laggards, including ourselves?

Just how widespread and important rapid anthropogenic evolution and maladaptation are in practice was unmistakable at a recent international summit of leading Darwinian ecologists, agriculturists and medicos at Heron Island on Australia’s Great Barrier Reef. Entitled ‘Interdisciplinary Solutions to Evolutionary Challenges in Food, Health and the Environment’, the goal was to both overcome and take advantage of the largely independent histories of evolutionary perspectives in these fields, and to build a common dialog of applied evolution. Interspersed, of course, with inspirational diving and snorkeling in Shark Bay, which lived up to its name.

For example, what are the underlying evolutionary commonalities and differences, for example, of

· immigration and invasions of pests and pathogens?
· emergence of genotype-environment mismatch and its influence on individual and population health?
· evolution of virulence and of antibiotic and pesticide resistance?
· sustainability of exploited populations and biological diversity?

How might these evolutionary challenges themselves interact in the context of broader global change? What strategies and lessons can be co-opted across fields?

The answers, or at least steps toward them, are available in video and print. Summit presentations are at http://www.icevolution.org/. From there, you can link to the papers, which form a special March 2011 issue of Evolutionary Applications, are available for download without charge (thanks Wiley-Blackwell!) through April 2011.

Probing the perilous future of the human-biosphere can often grant little more than an ever-grimmer view of how difficult the big issues will be to predict and manage, and for many, to survive. And now we toss evolutionary considerations– yet more variables– into the splashing mix! But I think we should instead take heart: evolution is the predictive core of all the biological sciences. Paleontology was merely a starting point. As we finally integrate evolutionary theory into widespread practice, we will surprise ourselves by designing better means of producing, protecting and preserving the things that we value most.

Photo: the Heron Island crew.

Science from the edge – part 1: explosive impact.

Ever read a paper and think “I wish I had written that”? I do all the time, but perhaps not in the sense you might think. Sure I would have liked to have written that book in 1859, or even those other ones in 1986 or 2000, but I am talking here about something a little less obvious. The ones I would really like to have written seem to be lost gems of science – the ones that have only been cited once or twice – or not at all. Of course, this means that the papers I would like to have written aren’t those that are influential but rather, as you will see, those that are fun and different and obscure for a good reason. I thought it might be a good use of this blog to bring some of these lost classics to the fore so that they can be appreciated or reviled by all as desired. And there are so many that it will take a few posts.

While doing graduate work in the School of Fisheries at the University of Washington, I happened to come across the intriguingly-titled “Use of dynamite to recover tagged salmon” written by Richard Tyler and published in 1960 as the US Fish and Wildlife Service Special Scientific Report 353. Now there is a title that immediately calls for further reading. It seems that the idea here was to put an array of dynamite charges in a stream and sit at the edge of the stream drinking beer and presumably smoking something while keeping an eye on the salmon swimming by. “Holy s**t Bob, there’s one with a tag, quick push the plunger.” BOOM. Then quickly, but probably not too quickly, they would run down to the stream to fish out the bits of fish, hopefully still attached to the tag. Perhaps they sometimes had to collect fish bits from up on the shore too – maybe they even sat under umbrellas to shield them from falling parts. Anyway, it turns out that “The experiments showed that dynamite is an effective means of killing salmon ...” No kidding. In fact, “they proved effective in the recovery of four tags.” Wow – now that seems like a business with a future.



And, in what appears to be a recurring theme from that era of fish biology, I later came across “Experiments in Lake Vaner on the influence on fish of bomb-dropping” published in 1949 in the Report from the Institute of Freshwater Research Drottningholm. And if that doesn’t make you want to read more, consider that the author’s name was Carl Puke. Truth in advertising. So this time, the concern was that the Swedish Air Force used this lake for bombing practice and the local fishermen were upset because the quality of fishing was somehow not the same – not to mention the discomfiture that ensued at the sound of an airplane while out fishing on some lazy Sunday afternoon. To address the hypothesis that bomb dropping was the cause of fish declines, “various quantities of fish were placed into rather large (how’s that for precise!) steelwire cages ... at different distances ... from the spot selected for the explosion.” Then, “the bombs were dropped from an aeroplane or placed by hand ... and blown up electrically.” I am not sure whether this more considered approach would induce more or less adrenaline than the “quick push the plunger” approach of the previous study. However, in contrast to that previous work, “After dropping a large number of bombs from a plane, no unconscious or dead fish could be observed in the area concerned.” But perhaps this reflects more on the quality of the Swedish armory than the quality of the Swedish fish. Maybe everything really is bigger in America – although the size of the explosions in these pictures might suggest otherwise – maybe the Swedes were using trick photography, as one might expect from fishermen.

Writing this post has got me to thinking that maybe I can write this paper after all. Here we have two opposing outcomes vying for academic supremacy. Moreover, perhaps there was some animosity between the groups – given that Tyler did not in 1960 cite Puke from 1949. How could a funding agency not see the logic of solving an outstanding scientific problem once and for all: do explosions commonly kill fish or not and under what conditions? The only problem is figuring out what category of “invasiveness” I need to select on my pending Animal Use Protocol.

Ps. Those in the know argue that the recovery of four tags in the salmon study really was valuable – because these tags were placed on fish in the middle of the Pacific Ocean to determine where salmon from different rivers went when they were at sea – and whose fish were being caught in what parts of the ocean. The problem was that people sitting at counting stations along streams would see a tagged fish swim by with no way to recover it. Until they got the plunger, that is.

Over-reviewed?

EP: Please submit original research articles for your presentations, not review papers.

Student X: What is a review paper?

EP: It is a summary of prior studies.

Student X: Why should we not pick them?

EP: Because they are summaries. The data are in the original studies – that is what I want you to focus on.

Student X: Submits review paper.

I have now had this conversation, and this result, more than once. So, why are my students picking reviews? And what does this have to do with eco-evolutionary dynamics when my class is on marine global change?

When considering these questions, I had a thought – maybe my students are picking reviews because there are so many out there. Perhaps a student choosing a paper at random has a relatively high likelihood of picking a review.

This reminded me of a question posed at the recent QCBS working group – is eco-evolutionary dynamics “over-reviewed?” This question stemmed from a recent flurry of reviews on the topic and the brief proposal that our working group supply yet another (we opted against). So I thought… if selecting at random, is an undergraduate student taking a course on eco-evolutionary dynamics more or less likely to select a review paper compared to a student taking a course on marine global change?

I did a bit of searching on Web of Science, and it turns out that reviews make up a larger proportion of papers on the topic of eco-evolutionary dynamics than on the topic of marine global change. For example, searches on “eco-evolutionary dynamics,” “niche construction,” “community genetics,” and “contemporary evolution” all independently yielded about 25% review papers (if papers categorized as “editorial material” are combined with papers categorized as “reviews”). Searches for common topics in marine global change, such as “coral bleaching,” “ocean acidification,” and “arctic warming” all independently yielded around 10% reviews.

So, it is unlikely my students are selecting at random. They are actively picking reviews – perhaps because reviews often present a more straightforward message than original research articles. And if the topic of my class was eco-evolutionary dynamics, they might be picking even more reviews. Of course, my quick-and-dirty analysis is admittedly imperfect. Many early research papers we would now consider to be eco-evolutionary dynamics, do not use one of the key words I searched. Nonetheless, 25% is a surprisingly high proportion.

So, is eco-evolutionary dynamics over-reviewed? Perhaps I will delve more deeply into that question next time. I have to get cracking on a paper on “the eco-evolutionary dynamics of marine global change.” It promises to be one heck of a review!

Eco-evolutionary dynamics in salmon

Empirical support for eco-evolutionary dynamics has emerged from several fish systems and a recent paper published in Heredity presents the case for diverse and strong effects in Pacific salmon (Carlson et al. 2011, Heredity 106(3): xxx-xxx). Several aspects of salmon biology make them amenable to the study of eco-evolutionary dynamics: they are philopatric (return to their natal sites to breed), anadromous (migrate between freshwater breeding and marine feeding grounds), and semelparous (die at the end of their first breeding season). Consequently, discrete populations can be subject to local selection pressures during their breeding season, presumably driving divergence in traits that can influence ecological processes. And such effects seem likely given their large adult body size and dense breeding populations that can change many features of the stream environment.

Building on earlier research that revealed the importance of water level and bears as sources of natural selection acting on breeding salmon, Carlson and colleagues (2011) explored the consequences of phenotypic change due to selection within a generation on salmon population dynamics, community interactions, and ecosystem processes. Despite a rash of recent studies documenting eco-evolutionary dynamics, little attention has been paid to the importance of this aspect of selection on ecological dynamics. Carlson and colleagues (2011) show how selection on body size simplifies age structure and strengthens cohort effects, which then alters population dynamics. They suggest two possibilities for how selection on salmon body size might then influence community interactions, namely through possible effects on bear energy stores (smaller salmon are less energetically rewarding, which might require increased foraging effort by bears) and aquatic insect community dynamics (smaller salmon dig shallower nests, which might differentially influence benthic invertebrates). Finally, the authors calculate the relative importance of selection (phenotypic shifts due size-dependent mortality) versus ecology (size-independent mortality) in determining the flux of salmon biomass across habitats. They report that selection can alter fluxes between habitats by up to 11% due to interannual variation in water level and up to 9% due to interannual variation in selection due to bears. The resulting combined effects of selection within a generation may have large cumulative effects on ecosystem processes. The authors speculate on such effects by comparing body size among nearby populations of salmon.

The authors thus conclude that phenotypic change within a generation due to selection influences ecological dynamics, and so should be considered within a complete eco-evolutionary framework. They also show that salmon are likely to be a good place to study eco-evolutionary dynamics.

Stephanie Carlson (Assistant Professor in the Department of Environmental Science, Policy, and Management, University of California, Berkeley)

Carlson, SM, Quinn, TP, and Hendry, AP. (2011). Eco-evolutionary dynamics in Pacific salmon. Heredity 106(3): xxx-xxx.

(http://www.nature.com/hdy/journal/vaop/ncurrent/pdf/hdy2010163a.pdf)

What did I learn today? Lessons from Leuven.

Andrew Hendry aghast at the apparent co-evolution of Belgian beers and glasses.

Every night at dinner, my family plays a game of “what did you learn that was new today.” Each of us has to come up with some new bit of knowledge, usually science-related, that emerged during the day. Often Aspen (7 years old) tells us about some new animal from a BBC video that we watched the night before. Usually Cedar (4 years old) tells us about how chameleons turn red when they are mad. She tells us this nearly every night and so it isn’t exactly new, but it is cool enough that we don’t mind. And then it comes to Heather or I. Sometimes we struggle to remember something new that we learned, which either means we knew a lot already or we didn’t pay much attention that day. This struggle has made me increasingly take mental notes of things that I learned on any given day to then relate to the family that night.

These past few days the task would have been easy. I have been attending a symposium on Eco-evolutionary dynamics, held at K.U. Leuven, Belgium. A host of talks from Belgians plus some visitors, as well as discussions in various restaurants and bars, has yielded a variety of cool new findings – new to me at least. For instance, I learned that only a few months of evolution in warm temperatures by previously cold-adapted Daphnia can make them perform as well – or better – in warm temperatures than Daphnia that had evolved in warm temperatures for centuries. I learned that the population size of southern elephant seals was probably upwards of one million individuals only a century ago. I learned that unrelated armoured catfish species, which have poison glands that deter consumption by predators, converge on similar color patterns in the same locations, presumably because this provides a more effective warning to predators (Mullerian mimicry). I learned that cuckoos, which lay their eggs in the nests of other birds, showed increasing convergence of egg shell color toward that of their host species (because the host would be less likely to reject the eggs) over the 20 years that a monk sampled nests in the early 20^th century. I learned that wolf spiders in Galapagos have independently evolved similar species in similar habitats on different islands. And so on and so on. Too bad I can’t spread these observations out and use them over a few weeks of family dinners.

But it wasn’t only science. I also learned that Belgian bars keep a specific glass for each of the dozens of Belgian beers they serve. It seems that each brewery has promoted – and provided – a signature glass that (presumably) best suits that beer. I am sceptical. Are they really trying to convince us that the co-evolution of beer and glass is so perfect that every brewery has discovered the best glass shape for their specific beer – and that this shape is different for each beer? Or would Westmalle Dubbel taste just as good – or better – in a Rochefort glass as in a Westmalle Dubbel glass? I doubt that the matching of beer to glass is really that critical. Maybe it is instead like sexual selection: the match tastes no better than a non-match but the chooser (us) thinks a match is somehow sexier than a non-match. So, with that in mind, my goal tonight is to buy four different beers, pour each into the four glasses corresponding to those beers, and then subject myself, Joost Raeymaekers, and Katja Rasanen to a blind 16-glass taste test. Here’s hoping we make it through the night.

Whisky Rescue

A wintery Mont St Hilaire is the location for the second Quebec Centre for Biodiversity Science (QCBS) workshop, this one on eco-evolutionary dynamics. A diverse group of ecologists and evolutionary biologists from south and north of the border met to argue and debate the new synthesis; when is it important, why is it important, how often? they cried. The ideas flowed almost as freely as the whisky, but by day 2 a new framework was emerging. Experiments for new data, analysis for new insights, and a synthesis to end all syntheses. One synthesis to rule them all!!!

An iconic example of eco-evolutionary dynamics is evolutionary rescue, the poorly understood means by which evolution can propel a population away from extinction. Few have considered the ecological consequences of evolutionary rescue, and fewer still, the community context in which these dynamics play out. The group will explore beyond genetic variation to also consider plasticity, niche construction, and evolutionary history. A new experimental model (marmite to the rescue) will be brought to bare (!) on the problem, and new theory to pierce the confusion.

By now the whisky fumes have penetrated the deeper parts of our muddled brains and we are staggering to the early hours of the late evening...Vellend aghast at East coast arrogance, Beisner aghast at the size of her glass, Yale obsessed with Bieber, Perry and Alewives...and a brand new H-index (how many degrees of separatation from Hutchinson)

Got to go, my whisky is getting lonely and my snowballs are getting cold. Andy Gonzalez signing off