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November 2009 Archives

The Level 3 & Scholarship examiners often ask you to discuss the evolutionary history of a group of organisms (Hebe, cockroaches, cicadas etc) in relation to the geological history of New Zealand. Geological changes such as the widening of the Tasman Sea, and the uplift of mountain ranges including the Kaikoura ranges & the Southern Alps, can drive evolutionary change through the isolation of populations (the Founder effect, genetic drift) & changes in selection pressures.

A new paper just out  has done just this for the moa (Bunce et al., 2009), combining "mitochondrial phylogenetic information from 263 subfossil moa specimens from across NZ with morphological, ecological, and new geological data to create the first comprehensive phylogeny, taxonomy, and evolutionary timeframe for all of the species of an extinct order." This includes evidence that for much of the last 30 million years or so, the North & South islands were geographically isolated, which would have provided the basis for allopatric speciation of the fauna & flora on those 2 landmasses.

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Like me, you may have seen this article in the Herald (or some other paper) on Wednesday this week. It tells the story of Rom Houben who, after suffering severe injuries in a car accident, was left in what doctors diagnosed as a 'persistent vegetative state' for 23 years. His mother, however, was insistent that her son was still both conscious & alert. Eventually, PET scans of his brain indicated that this appeared to be the case, & the article tells us that after 3 years of intensive therapy "the 46-year-old is now communicating with one finger and a special touchscreen on his wheelchair."

If only things were that simple...

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Such a cute t-shirt logo (I want one!) but it has the FAIL in so many ways when it comes to evolution...

evolution of the cat.jpg

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Well, the mad rush to confirm degree completions is finally over (6.32pm & counting...) & I'm off to meet Marcus at the pub for the last Cafe Scientifique of the year. The topic: strange science. It's open for the audience to bring up any topics they want to discuss, but we have the odd (& I use the word advisedly!) idea of our own :-) Including the problems of queuing on buses, baguette-carrying birds & the Large Hadron Collider (ask Marcus!) , Chickenosaurus rex or, rejigging chickens & getting dinosaurs, & of course fellatio in fruit bats :-) An entertaining time should be had by all!

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Last Friday the Science Media Centre's media alert included the following:

Dietary supplements such as multivitamin tablets and energy drinks are an increasingly common part of our lives, but should they be?

Concerns have been sparked recently by the availability of ultra-high
caffeine energy drinks, the proliferation of people taking (often large) doses of vitamins/minerals every day, and an industry which appears to have very little legislation to guide its behaviour.

I will confess to having drunk caffeine 'energy' drinks in the past (despite their - to me, anyway - awful taste) when I've been particularly tired & had to keep working. Not because they contained energy - caffeine has a stimulant effect on the nervous system, so the only energy content would be in the sugar added to the drink, & anyway I went for the sugar-free kind! But I stopped when I found that my blood pressure had gone way too high & that my teeth 'buzzed' after I'd drunk one. And that was on the basis of one per day & not every day... Certainly caffeine can have negative physiological effects. (I was intrigued to discover that coffee & other caffeinated drinks aren't recommended for anyone with a tendency to faecal incontinence, for example.) So I'll be interested to see the briefing notes tomorrow.

But I also wonder how the idea of regulating vitamins & other 'dietary supplements' (I'd go as far as to include complementary & alternative medicines (CAM) in this grouping) will go down with the wider community. Certainly the last time the idea was raised, the outcry from various interest groups led to the whole thing being quietly dropped. Which I thought was quite interesting - you'd think there'd be a lot of support for something which would ensure that the pills & potions that fall under the 'supplement'/CAM umbrella would contain what they are claimed to contain, and in standardised amounts. This would after all be beneficial to the consumer - there are significant safety issues associated with non-standardisation of these supplements, and also with contamination by non-declared heavy metals (or even prescription drugs). So why the fuss?

It's certainly a discussion we need to have, & hopefully one that will be better addressed by the media than has been the case in the past.

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One of the deepest divisions among living things is the split between prokaryote and eukaryote cells. In eukaryote cells, the chromosomes are enveloped in a layer of phospholipids - these cells have a 'true' nucleus surrounded by a nuclear membrane, something that's absent from prokaryotes. And there are other differences: eukaryotes either have, or have had, mitochondria (tiny organelles where aerobic respiration occurs) and plants & algae also have chloroplasts, & there's a lot of other cellular infrastructure besides. Now, we teach students about the origins of mitochondria & chloroplasts (most likely by the process of endosymbiosis, first put forward as an explanation by Lynn Margulis), but what about that nucleus?

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One of my commenters asked the following question, & while I answered it quickly in that thread, I thought it might be useful for her (& maybe others) if I found a few references to support what I said.

One of my friends has this as their current status on Facebook, and I wondered if you had some facts at your fingertips which I could steal to reply (as I'm sure it's not scientifically sound):

"the swine flu itself has killed about 2-3,000 people total. The regular flue kills 40,000+ per year. The vaccine contains 2 dangerous compounds, one is thimerosol. It is made 50% of mercury. It binds to receptors in your brain, and can cause brain damage. The other is squalene. It accidentally tricks your immune system into killing your own cells. So people, what do we think?"

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Procrastinating like crazy, I've just come across an interesting post over on Science-Based Medicine. It's about the hazards associated with water births (sometimes promoted as a 'natural' way to deliver a baby...). I've wondered before about the sense of delivering a baby under water (the 'diving' reflex only kicks in in cold water & no mum-to-be is going to sit around in a chilly tub) but I hadn't really thought before about the microbiological side of things. Faecal contamination (eg via meconium) + body-temperature water - not a good combination...

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This afternoon the daughter sat Level 3 Biology (she seemed to quite like the paper). She said that one of the questions was about Darwin's finches, based on some of the work of Peter & Rosemary Grant, who've been studying finches on the Galapagos Islands since 1973. During that time they've trapped, measured, banded & re-trapped every finch on the island of Daphne Major, collecting longitudinal data on the birds in perhaps the longest-running study of its kind. Among other things, the Grants were able to document how the finch populations changed in selection to the selection pressures imposed by a severe drought.: evolution in action. Nonetheless, a stock creationist remark concerning the Galapagos finches claims that this is not an example of evolution because the birds 'are still finches and the changes cycle with changing environmental conditions.' 

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One of the nice things about reading books by great science writers is that I just know I'm going to learn lots. I've just got back into Nick Lane's latest book Life Ascending (it's been my lunchtime reading at work & recently other things have intruded...). Lane has a lovely lyrical way of writing that I really enjoy, & I thought I'd share a couple of paragraphs with you. They're from the chapter titled Sex: the greatest lottery on Earth. in which he's discussing how & why sexual reproduction evolved. At the heart of this excerpt is the idea that the biological costs of sex are quite hard to measure, but can be very high. The example here is hummingbirds - the go-betweens for sex in many species of tropical plant.

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Last week I attended the launch of Science OlympiaNZ, a charitable trust set up as an umbrella group to support New Zealand's various International Science Olympiad programs (& very generously supported by the Todd Foundation)Among the speakers was Max, a member of this year's highly successful NZ International Biology Olympiad team. Max gave a great speech, & I enjoyed it so much that I asked if he would allow me to post it here as a guest blogAnd he did! Thanks, Max!!

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No, this has nothing whatsoever to do with biology... well, that's not quite true - there's an exploding whale included :-)

I remember that one year, early in my secondary schooling (yes, a loooong time ago!), there was a rumour that some young man at Hastings Boys High had disposed of some illicitly-acquired sodium by flushing it down the loo. With the inevitable result - a loud noise & an awful lot of mess. Apocryphal or not, the tale did ram home the dangers of playing with sodium, which reacts rather violently with water.

How violently? Visit this site & find out - 15 explosions, including the results of dropping drums of sodium in a lake, alongside the biggest nuclear device ever detonated, blowing up 100 tons of TNT for no particular reason, and - the exploding whale!

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A couple of years ago now, we held a Cafe Scientifique with the topic 1080 - friend or foe? Topical then (it drew a large crowd, wtih people from both sides of the debate) & just as topical now. On the one hand, 1080 is promoted as our current best option for the control of possums, mustelids (mainly stoats & ferrets), rabbits, & rats. Those opposing its use describe it as contrary to our image as a clean, green nation; harmful to a range of non-target animals, & potentially a threat to water supplies. 

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A while ago now I wrote about the '10 questions to ask your biology teacher', promoted by Jonathan Wells of the Discovery Institute. It seems that - in the US anyway - creationists cdesign proponentsists have moved on: the list has transmogrified into 'Ten questions to ask your biology teacher about intelligent design'. Over on Pharyngula, PZ has dealt to each question rather thoroughly & in a way which also highlights the nature of science - well worth going over there to read :-)

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Just a quick post as I'm away on a panel meeting & my brain is tired - but here's something else from my file of 'things I didn't know': Florence Nightingale was a statistician.

Now, I heard all about Florence Nightingale when I was a kid. She made a major contribution to the development of nursing as a profession, and saved large numbers of British soldiers during the Crimean war through her insistence on good hygiene in the hospital wards. "The Lady with the Lamp" & all that. But what these stories didn't tell us was how she managed to persuade the medical profession of her day that she was right & they were wrong. After all, she was a) a woman & b) had no training or (to begin with) reputation in the field.

The answer, as I've discovered through reading Ernst & Singh's book Trick or Treatment (on which I must write more, another time, but you can read Amazon reviews here) is that she was able to marshall statistics in support of her claims. It turns out that Florence's papa was a very progressive gentleman (for Victorian times), who insisted that she should receive a proper education. This included mathematics along with languages & history. His daughter put this to good effect, producing a large body of data that clearly demonstrated how soldiers under her care did better than those receiving the conventional treatments of the day. She also showed that professional nurses provided better care than the more usual untrained attendants. When doubters pointed to an apparent higher mortality rate among her trained nurses' patients, Florence was able to show that this was because her nurses were receiving patients who were already seriously ill; when this was taken into account, the professionals came out well ahead.

Statistics were then, & remain, a very powerful tool of science - anyone considering studying the sciences should also give serious consideration to a side helping of stats :-)

But I must get back to the book, I'm sure there are more intriguing things for me to learn!

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A couple of weeks ago Marcus Wilson & I were down in Taranaki to run a Scholarship preparation day. During one of my sessions the biology students & I were discussing the concept of 'species'. Most of you are probably familiar with the idea of a 'biological species', defined by its lack of ability to interbreed with members of other populations. Well, we agreed, that works just fine for living organisms, but what do you do about fossils? The answer is that we tend to rely on a 'morphological species' concept, identifying likely members of a species on the basis of structure & appearance (morphology).

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I spent a lot of last weekend marking exam papers from my first-year bio students. Most of them chose one of my essay questions (it's a team-taught paper & they had a choice of 3 essays in my section), & today one of the class told me that she'd really liked that question because it got her thinking. So I thought I would share it with you :-)

Rhagoletis pomonella is a small fly native to North America. Normally its larvae burrow in and eat hawthorn fruit.

Apple trees were introduced to North America from Europe in the 1800s. There are now two sibling species of Rhagoletis. In one species the larvae feed on hawthorn fruit, and in the other the larvae feed on apples. Neither species feeds on the other’s food, even when hawthorns and apples are found growing in the same area. Female Rhagoletis use scent to identify their host plant’s fruit.
 
Identify the pattern of speciation shown by Rhagoletis and discuss how this could have occurred. In your answer, you should consider the various isolating mechanisms that could be operating in the Rhagoletis sibling species.
 
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On the news last night we watched fascinating footage of dinosaur footprints, found at a location in somewhere near Nelson, in the South Island. (A secret location - if their whereabouts should become widely known, you can bet there'd be unscrupulous fossil hunters in there, chipping out slabs of rock with footprints in them, for sale to equally unscrupulous collectors.) While dinosaur trackways have been found in a number of other countries, this is a first for New Zealand. Joan Wiffen would, I think, have been delighted :-)

 

 The footprints were found at several places over 10km or so. It seems that they were made by sauropd dinosaurs walking across tidal mudflats - the footprints would have been quickly covered by sediments when the tide came in. At one site there are 20 footprint impressions (a 'trackway'), which is great as they can be used to give an indication of how fast the animals were moving. Using data on stride length (from trackways) and estimates of mass from skeletal features, it's possible to estimate an animal's speed. (There's an on-line calculator that will let you work this out, if you should be so lucky as to find a trackway of your own. And certainly it's possible to predict where more such finds could be made, in similar sediments of the same age.) Some of those estimates seem excessively high (eg 88kph), but still it does appear that dinosaurs could get up to some fairly impressive speeds, given the sizes that some of them attained.

It's worth remembering that not all dinosaurs were the giants of popular perception. Computer simulations have suggested that the fastest of all was the tiny Compsognathus (at an estimated 3kg, the same size as our ditzy Burmese cat), which could have left Usain Bolt in the dust. The fact that even large dinosaurs could reach speeds of several kph when walking has been used to suggest that they were homeothermic, capable of maintaing elevated body temperatures. This may have been more likely in the larger animals, where mass homeothermy would come into play (large bodies will warm up more slowly, from the sun's heat or by exertion, but will also cool more slowly). Perhaps the most readable discussion of dino homeothermy remains Bob Bakker's entertaining (& still, in places, controversial) book The Dinosaur Heresies.

I'll look forward to the scientific description of this discovery, due to be published next month. But in the meantime, isn't this just such exciting stuff?

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A quick post (I'm hoping to write something more substantial on a new paper, but at the moment I've got student appointments all day & I'm writing this in the gaps between two of them): this link is to a video (teachers - it's downloadable) about an experiment demonstrating rapid evolution in a plant virus (the 'tobacco etch' virus). And thanks to ERV for alerting me to the site.

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From the Letters to the Editor (we should, apparently, be concerned that most people don't know the form of fluoride in our drinking water...)

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The following quote comes from an article about science clubs in the UK, aimed at 12 & 13-year olds & intended to stimulate interest in science:

"The ultimate aim is to enthuse young people about learning again...We want the clubs to help kids to see that science isn't just about crazy, white-haired men in labs cooking up noxious substances, and that engineering doesn't just involve greasy car mechanics. We want to encourage them to learn that Stem (Science, Technology, Engineering, Maths) subjects are a really positive force all around us – and to have fun while doing so."

And apparently the primary-school kids hanging around some of the practical classes get a blast, too. Which is as it should be - children are fascinated with the way the world works, & the more we can further that interest & encourage them to get into science & related areas, the better.

Our own government appears to recognise the significance of science & technology: from Wayne Mapp's speech at Waiariki Institute of Technology, on October 15:

The next area of achievement I am focused on is the performance of the research, science and technology system. As the Prime Minister said last month, at the launch of the Primary Growth Partnership, "we need to put science at the heart of this National-led Government ".

And the Royal Society recently announced the list of primary school teachers who have won fellowships for the coming year, during which they'll work alongside scientists in a range of host organisations. The intention is that they'll become science curriculum leaders on returning to their schools; a worthwhile aim given the woefuly low amount of time given over to science in the primary school curriculum:  "science education is currently not high on the priority list at primary schools, with an average of just one hour per week taught."

It's hard to see how all this sits in the light of the government's recent announcement that there will be no additional funding to support science & the arts in primary schools next year, with the money going instead to the new 'national standards' in the three Rs. As Paul Callaghan said in his lecture, Beyond the farm and the theme park, our future lies in science and technology, and this obviously requires a society that values those subjects & is (to some degree at least) scientifically literate. And the spark of interest in science should be lit, and nurtured, in the youngest members of our society.  I congratulate the Royal Society primary school fellowship holders & wish them well - but they will need signficant support on returning to their classrooms if we are to maximise this investment in our future.

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I've just started reading Richard Dawkins' latest book, The Greatest Show on Earth, & I'm thoroughly enjoying it. (At this point I should confess to a small heresy - in the past I haven't always enjoyed his books. Not that they're badly written - the reverse is true! But they just didn't always gel for me. This one's very different.) The book's focus is the evidence in support of evolution, and it makes it clear why evolution underpins all of modern biology. So you will see why I was excited to get my hands on a paper called Making evolutionary biology a basic science for medicine (Nesse et al.2009 - Auckland University's Sir Peter Gluckman is among the authors).

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