In one of our first-year biology labs the students spend a bit of time looking down the microscope at various algae & protozoa. Some of their samples come from a container of interestingly weedy water from my fishpond. Not only is the pond covered with duckweed & Elodea, but it turns out to have a wide range of tiny unicellular plants & animals, & some not quite so tiny, such as Volvox.
July 2010 Archives
I really enjoy my first-year bio classes, & one of the reasons for this is that the students respond to my questions and ask questions of their own. I've just read Marcus's excellent post on what he's learned from his students & it's spurred me to write a bit about this too.
As someone with a dog in my life, I couldn't ignore that heading in the Science news alert that hits my in-tray each Friday. Of course, it couldn't possibly apply to my little Ben :-)
OCD = Obsessive-Compulsive Disorder - an anxiety disorder; according to the Nationaal Institutes of Health website I linked to here, people suffering from it typically have recurring, unwanted, anxiety-generating thoughts (the 'obsessive' part of the syndrome) &/or repetitive behaviours that may reduce the anxiety (the 'compulsive' aspect). Now, I know that in captivity some animals can exhibit quite pronounced obsessive behaviours - pacing, licking, chewing inappropriate objects - so I was interested to read the article itself. It's a profile of a vet, Nicholas Dodman, who does a lot of work with dogs who demonstrate a range of behavioural problems, at least some of which could be described as obsessive or compulsive.
I saw a news story today on a bacterium that can withstand very high radiation exposure, freezing cold, & exposure to vacuum. Cool stuff. Said bacterium isn't alone in this, mind you, as I know from my colleague Allan Green that lichens have had much the same treatment, shot up into space & reviving once in more congenial conditions.
A few other organisms are capable of similar feats: tardigrades ('water bears') can survive losing up to 90% of their water content & while in this desiccated state can be frozen, plonked into ether, all sorts of nasty things, only to spring back into action once rehydrated. 'Higher' animals can't cope with such extremes, but some can still survive conditions that would test most eukaryotes.
Well, it's not too great a leap, is it? I thought of this post because over on the Sciblogs copy of my last item we started talking about sperm competition. We got there via Drosophila bifurca.
Some of the things lecturers say make a lasting impression on students' memories (albeit not always for the desired reasons). I remember, when I was a biology undergraduate, hearing about some of the undesirable effects of filiarid worm infection. According to the lecturer, in extreme cases this could lead to infected men having to 'carry their balls in a wheelbarrow'. At the time we found this painfully funny (although I imagine some of the guys crossing their legs in sympathy) but at the same time I did wonder if this wasn't just a case of exaggeration for effect :-) But in the age of google, I can report that it was not; well, not exactly. (Warning: persons of the male gender may find what follows a little unsettling....)
This morning's Waikato Times carried the following headline: Heavens aligning for fiery possium cure. Now, there's a lot of pressure on to find viable alternatives to 1080 as a means of controlling possums, but somehow I don't think the method described in the Times story is going to take off.
The news item tells us that possum skins burnt to ashes under the right alignment of the Moon and stars could be an alternative to 1080 - & the group promoting this is asking for $330,000 of Environment Waikato funding to demonstrate it. My first thought, on reading this, was 'you have to be joking!' Subsequent thoughts were much the same. Why?
We tend to look at the past through the misty lens of memory, but still I rather think my siblings & I had a lucky childhood. I don't remember that we had a heap of money (pocket money was doled out at the rate of a penny for each year of one's age - doesn't that date me? - but then, aniseed balls were 8 a penny!) but Mum & Dad made sure we had rich & varied experiences. An elderly friend of ours still recounts how Mum would get Dad to stop the car, on our regular 'Sunday drives', if she saw something that might be good in the family 'museum'.
Over on SciBlogs Aimee has started a discussion around the apparent psychic powers of Paul, the octopus who's claimed to have predicted the results of several games in the just-ended soccer World Cup. (Actually, if he could predict the outcomes of games, this would make him prescient, not psychic. Once a pedant, always a pedant, alas!)
Those of you who are thinking of entering for the Scholarship Biology exam at the end of the year may have had a look at the statement of just what is expected (the 'performance descriptors'). If you have, you'll have seen that one of the key attributes you need to demonstrate is an ability to think criticaly: about the question; about the supporting materials that the examiner may have provided; about your own knowledge (you don't want to do a brain dump, after all - this will not impress the examiner one bit!).
I've written quite a bit about this in the past (here, here, & here, for example). Today I thought I'd add to that, with a closer look at some of the questions that you, as a critical thinker, might ask about a topic. (This is a modified version of something I've posted on the 'other' blog, Talking Teaching, wihich I share with my colleagues Marcus & Fabiana.)
If, like me, you enjoy soccer you'll have been excitedly following the World Cup games. You will probably have caught some of the other hoop-la - including the 'news' coverage of an octopus that purportedly 'predicted' the outcome of games involving the German team. Now, I've been bemused by the coverage accorded to this cephalopod 'psychic' - does the press really think Paul the octopus can predict the outcome of a soccer game? I'd like to be charitable & think it's just reporters looking for a 'feel-good' story, or misunderstanding the nature of probability...
After all, let's look at what the octopus is doing. Offered 2 flag-bearing boxes (one with the German flag, one with the opponent's), each containing a mussel, he chooses one of them. For the 6 matches involving the German team he appeared to select the winner of each game, including the one that saw Germany go home & Spain progress to the final of the world cup. (A rather tedious game, I have to say...)
Gasp! Surely this is due to more than chance? Well, no. If you toss a coin & record whether it comes up heads or tails, over (say) 100 tosses you'll see 'runs' of several heads or several tails. But each time you toss, regardless of what's gone before, there's a 1 in 2 chance of coming up heads. And that's probably what we're seeing here. Offer Paul the same choices, multiple times, & I'd predict that you'd see similar results - sometimes he'd be right, & sometimes wrong, & sometimes there'd be a run of correct 'choices'. (But no-one's going to do that, of course, because they don't see a story in it.) However, humans are pattern-seeking creatures & we seem predisposed to imbue mere coincidence with far more meaning than it actually has. And given the amount of press coverage given to self-proclaimed psychics of the human variety, perhaps I shouldn't be too surprised that the octopus, too, has gained his moment of fame.
Today Marcus Wilson & Kathrin Otrel-Cass hosted Science in the Public, a symposium for people involved in communicating with the public through a range of initiatives (including Cafe Scientifique aka Science in the pub). And there's what looks like being a most promising Cafe event tonight, with Shaun Hendy leading a session on nanotechnology. Anyway, one of the presentations really caught my imagination, & I thought I'd talk about it here.
Thanks to herr doktor bimler & the University's science librarian, I now have my hands on two copies of the paper I mentioned a couple of posts ago: Positive allometry & the prehistory of sexual selection (Tomkins et al., 2010). The term 'allometry' refers to the relationship between the size of an organism & the size of various parts of that organism. When scientists study allometry, they might do this for various stages in the growth of an individual, or they might compare different organisms of the same species, or individuals from separate species. 'Positive' allometry means that as body size increases, so does the size of whatever other feature's being examined. (The Panda's Thumb has an example of this, for body size: brain size ratios in primates.) The paper by Tomkins et al. looks at the spiny 'sails' on the backs of pelycosaurs & the crests on pterosaurs' heads, and suggests that differences in size between male & female individuals is related to sexual selection.
(I did wonder about using all Ks for that title...)
In studying the animal behavior part of the curriculum, you may well have read about courtship & mating systems. In many cases it's the male that initiates courtship, & sometimes they use very elaborate displays to catch the female's eye. Think of birds-of-paradise and bower birds as examples. This elaborate behaviour, & the physical features that often go with it (such as brightly coloured plumage or massive racks of antlers) are viewed as the result of sexual selection. If an individual has a feature that enhances their chances of mating successfully, and that feature has a genetic underpinning, then it may be passed to some of their offspring & over time spread through the population. This tends to be a bit one-sided, in that females tend to be the 'selective' sex & so sexual selection tends to affect males more than females. In fact, 'sexual selection theory predicts hat females... invest less in courtship signals than males' (Berry & Breithaupt, 2010)
From yesterday's RSNZ news headlines:
Size mattered for flying dinosaurs: New research into pterosaurs and pelycosaurs shows their grand headcrests and sails were developed to attract a mate, not to regulate body temperature as first thought.
Now, you may think me a palaeontological pedant (& this is not a cue for cracks about my age from the cheap seats!), but I find that loose use of the word 'dinosaur' really irritating. Why? - because neither pterosaurs nor pelycosaurs were dinosaurs. I know the headline's more eye-catching than saying 'size mattered for prehistoric flying reptiles', but still, it bugs me.