Posts Tagged ecology

helicobacter pylori and the complexity of the human microbiome Alison Campbell Jul 24

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In their first-year microbiology lectures. our students hear about Helicobacter pylori, the bacterium associated with the development of gastric ulcers (a discovery that eventually saw Barry Marshall and Robin Warren receive the 2005 Nobel Prize for Physology or Medicine). The trouble is, I suspect that this is all that they hear about a story that is considerably more complex.

The story of H.pylori is just one part of Jessica Snyder Sach's highly readable and thoroughly-referenced book, Good Germs, Bad Germs, which introduces the reader to the complexities of the human microbiome: the intricate microbial ecosystems found on and within the human body.

Good Germs, Bad Germs: health and survival in a bacterial world. Jessica Snyder Sachs (2008) pub. Hill & Wang. ISBN (e-book): 0809016427

The book begins with the harrowing tale of a young man's death from a rampant MRSA infection, and of a child living with multiple life-threatening allergies.- two tales linked by the unforseen effects of our overuse of anitbiotics and our fixation on hygiene. (Actually, the former was not entirely unseen: in his 1945 Nobel Prize lecture, Alexander Fleming commented on the possibility that overuse of penicillin could see the development of resistant bacteria. Unfortunately, at the time this warning went unheeded – if indeed it was really heard – for example, penicillin was available as an over-the-counter drug in the US for almost a decade after its introduction in the 1950s, which would undoubtedly have contributed to the development of resistant strains of microbes.)

Then, after an introduction to the "war on germs" and scientists' search for the 'magic bullets' that would (it was hoped) allow us to vanquish them forever, it's on to "life on man". Wherein I learned heaps, including the thought-provoking suggestion that there may be some adaptive significance to the fact that babies usually exit the vagina with their heads face backwards, towards the mother's anus. For babies guts are colonised by bacteria very soon after birth – & they may receive an inoculum of faecal matter on the way out, to join the lactobacilli  from the vagina itself and bifiobacteria from breast milk.

Incidentally, while all this may sound uncomfortably germy, there's good evidence that the gut microflora are essential for survival. Lab animals reared in absolutely germ-free conditions, & whose guts never develop a microbial flora, fail to thrive. What's more, Snyder Sachs  comments that the combined acction of several species of intestinal bacteria "liberate as much as 30 percent of the calories a person absorbs from food, especially from high carbohydrate meals."

Reading on – and it was really hard to put this book down! – you'll hear about the hygiene hypothesis, which suggests that many of the inflammatory diseases that plague us today are an unforeseen result of lives that are too clean. Along with this is the 'dirt vaccine': the idea that vaccination with a mycoplasma may help to redirect the overzealous immune response underlying many allergies. Then it's on to a deeper look at the development of antibiotic resistance and the rise of the superbugs, which has been exacerbated by the widespread use of antibiotics in farm animals. (Encouragingly, Snyder Sachs notes that banning this use, as in the Netherlands, can lead to a reduction in 'superbug' prevalence.) And finally, we look at our options for the future, and whether we can find a way to live in balance with our burgeoning microbial ecosystems.

And H.pylori? It turns out that this particular bacterium has been with us for at least 60,000 years, something that's been used to track human migration patterns that began when Homo sapiens first left Africa. H.pylori colonises the stomach in the first few months of life, before gastric acid secretion really ramps up, and can actually affect that acid secretion, lowering the pH enough that Helicobacter can survive but most other species are killed. There is a plus to this: the lowered pH reduces the effects of acid reflux & the development of oesophageal cancer. But then, there's those gastric ulcers – which apparently didn't really become an issue until the 1830s, when this was mainly a disease of the upper classes, possibly linked to a decline in colonisation related to improved sanitation and the use of early antibiotic products. And gastric ulcers

remain virtually unknown in undeveloped regions of the world such as Africa, where most people become colonised in infancy. It may be that delaying or disrupting H.pylori colonisation with water sanitation or antibiotics has somehow altered the immunological 'truce' that this microbe forged with our immune systems over thousands, possibly millions, of years.

I like the full, more complex story; it's so much more satisfying than the 'helicobacter – bad' version, and it's a much better reflection of the dynamic relationship between humans and the microbes that call us home.

most excellent epiphytes Alison Campbell Mar 28

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A couple of years ago I spent a lovely afternoon in the huge domed glasshouses of Singapore's "Gardens on the Bay". The 'cloud forest' was my favourite – both for the concept & for the wonderful range of epiphytes on show there.

Singapore cloud forest mountain.jpg

So you'll understand that I enjoyed reading about it again on this blog, written for the New Zealand Epiphyte Network. Anyone with even a passing interest in New Zealand's native plants should drop by the site. And maybe sign up to be part of their citizen science project while you're there?

Go on, you know you want to :)

it’s not all fun & games being a crocodile, you know Alison Campbell Mar 09

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Crocodiles (& their relatives, alligators) are generally viewed as top predators. They're 'ambush' hunters1, lunging up out of the water to snatch at their prey at the last moment.

But sometimes, they come off second-best. Check out this video on the National Geographic site, of a jaguar stalking, catching, & killing a caiman.

And how about these images of a rather large boa chowing down on a metre-long crocodile? Or an otter, eating a juvenile alligator?  Yep, it's not all fun & games being a crocodile.


1 Having said that, when I was writing this post I came across the intriguing suggestion that some crocodilians use sticks to lure birds within lunging distance ie that they use tools. They've been observed doing this only during the birds' breeding season, when their feathery cousins2 are looking around for sticks to use in nest-building.

2 Taxonomically speaking, crocs and birds are both archosaurs. Early crocodilians – the pseudosuchians – were a predatory force to be reckoned with & it's possible that the pseudosuchians' demise, in the mass extinction that marked the end of the Triassic, was a factor that opened things up for the expansion of the dinosaur lineages.

of whale poo, wolves, and spiny s*x Alison Campbell Feb 20

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Whales – competing with us for food, or helping to sustain the phytoplankton production on which most life in the oceans depends? The story and video at this link make a good case for the latter. 

Then there's the wolves – their return to Yellowstone Park in the US has led to a whole cascade of environmental changes: changes that are very much for the better. Because the wolves keep the elk population moving around & to some degree under control in terms of population size, the vegetation has had a chance to recover from overgrazing. Forest regrowth along the riverbanks has stabilised those banks and contributed to an improvement in water quality. Beaver populations have bounced back & their activity has further altered the landscape in ways that have seen other species return or recover. The wolves have benefited the park's ecosystem in ways that nobody had predicted.

As for the final topic, well… I have occasionally been asked by much younger, smaller persons how hedgehogs "do it" (the answer being, "carefully!"). In fact Nanny Ogg had a hum'rous song on that very topic. Brian Switek discusses the issue as it might relate to stegasaurs in My Beloved Brontosaurus. And then there are porcupines, animals for whom it seems all coitus must be consensual (unlike ducks, bedbugs, & dolphins, to name just three). Because anything else really wouldn't work…

presenting on plants at WCeLfest Alison Campbell Feb 16

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For the last few years our Centre for e-Learning has run WCeLfest – a day of presentations & discussion around using various technology tools to enhance teaching & learning. I always find these sessions very valuable as there are a lot of people doing some really interesting things in their classrooms, & there’s always something new to learn & try out myself. I offered to run a session myself this year, which is what I’m going to talk about here, but I was also asked to be on the panel for a discussion around what universities might look like in the future, and that was heaps of fun too.

My WCeLfest session was billed as a workshop, so to kick things off I explained that the attendees were going to experience being in what is effectively a ‘flipped’ class, getting the students’ perspective, and why I’d developed the class in the way that I had. (I added that feedback on that experience was welcome!) I think there was one biologist in the room, so for most of those present the things they’d be doing would be just as novel as they will be for many of my students.

First, my ‘class’ got some extra background information. If previous years are anything to go by, then about a third of the students in my first-year biology class won’t have studied the year 12 Achievement Standards related to plants1. This always poses something of a challenge as we run the ‘plants’ part of the paper first, flowers & fruit being readily available in late summer (& I doubt things would be different if we taught it later in the paper). So I’m always thinking about improved ways to bridge students into the subject without boring those who have a reasonable background in things botanical.

The first lecture looks at what plants are & why they’re important, both ecologically & in terms of human history. For the last 2-3 years I’ve used an active learning exercise, putting up a graph on changes in atmospheric oxygen over the 4.5 billion years of Earth’s existence and asking the students to interpret and discuss the information it shows. But, using the same graph with a different group of learners, I realised that some of my students might not even know what photosynthesis entails, which would rather destroy the purpose of that part of the class.

So this year, they’re getting homework for the night before: this video. And at WCeLfest, we watched it together.

As you’ll have seen, there are a few, very basic, questions at the end of the video, but we stopped the video before reaching the quiz & instead briefly discussed and answered each question in groups, plus there were some additional queries, which was great. The original set of questions reinforce the basic concepts & give those students who were unfamiliar with them a bit of confidence that they’re prepared for the next step.

Now, for my ‘real’ class I’ll be showing an additional, more complex video, but for this shorter session we just moved on to the data interpretation.

Again, I explained the rationale behind this part of the session. I’d decided to do this exercise with my first-year students for a couple of reasons: firstly, to break up the class and get them actively engaged in the learning process; and secondly, to give practice in the process skills needed to interpret information provided in graphical form. The question they needed to address, using their knowledge from the video and the data in the graph, was: without plants, life as we know it wouldn’t have evolved in the first place. Why not?

O2 concn over time.png

As I do in my normal classes, while the class split into groups to come up with an answer, I circulated between those groups2 in order to hear what was going on & field any additional questions. “What was the atmosphere made of before photosynthesis began?” was one, which led to a brief consideration of how the Earth formed. And I needed to explain oxidised/oxidation, as well. This was a really valuable process for me as it’s highlighted a couple of areas where I need to do a little more background work with my first-years.

A quick summary of the class discussion: the ‘oxidation’ part is important because that’s how we know when oxygen generation began – iron-rich rocks began to rust. It wasn’t until the exposed rocks had been oxidised and the ocean had become saturated with oxygen, that oxygen began to be released into the atmosphere, as evidenced by more oxidised rock. As O2 accumulated in the atmosphere, the ozone layer formed, offering protection from the sun’s UV radiation & allowing living things to move onto the land.

And we finished with a quick look at the ‘design-an-organism’ class that I’ve previously blogged about.

The feedback was very positive, with several people saying that they could see how they might use the flipped classroom technique in their own teaching. It was also lovely to hear someone say that they’d got a bit worried when they realised we’d be talking science, but that they’d really enjoyed the experience and learned some new things along the way. And I’d learned ways to improve the exercise, so the enjoyment & learning were mutual


1 These are AS91155 Demonstrate understanding of adaptation of plants or animals to their way of life, and AS91156 Demonstrate understanding of life processes at the cellular level. You’ll find them here on the NZQA website.

2 In my ideal class3 there’d be an ‘aisle’ between every 2 rows of seating, to allow teachers/facilitators to move more freely among the students.

3 I can dream, can’t I?



concerns & conspiracy theories Alison Campbell Sep 26

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Any discussion around water fluoridation will bring up quite a number of concerns, but increasingly – on-line anyway – conspiracy theories also come to the fore. I think the latter need to be addressed, but not at the risk of ignoring or failing to address the former. Worrying about the nature of what’s in our water supply, & its possible health impacts, is both natural and understandable – especially given that there’s so much information (of varying quality) out there, & sometimes the people you hear are the ones who shout the loudest. Which is not necessarily the same as those who have the strongest case. As I’ve said before, that’s what drew me into this debate in the first place: the way science has been misrepresented by those wishing to bolster a case against water fluoridation.

My own personal opinion is that the issue should really be addressed in terms of ethics and societal responsibilities, and it’s sad to see that attempts to have this discussion (on-line, anyway) are so often diverted yet again to a you-said-we-said about the science. I do wonder what this does for those ‘lurkers’ who may be following the to-&-fro – & I see I’m in good company in that respect.

Actually, it must get really confusing, for reading some of the on-line comments about fluoridation, I’m still surprised at how often conspiracy theories crop up. (I shouldn’t be, I suppose, but I am.) The pharma shill gambit is quite common: the idea that people holding views that differ from the speaker’s, must be being paid to hold them. In the case of fluoridation, I think people need to do their sums. In Hamilton, the cost of buying HFA to add to municipal water supplies was around $48,000 each year. That’s not a lot to go around all the local scientists, dentists, healthcare workers, and humble bloggers accused of being bought by big business by anti-fluoride activists… (This is something also addressed in Harriet Hall’s excellent post over at Science-Based Medicine. Bob Park’s ‘seven signs of bogus science’ is also relevant.)

One might well ask why our opinions need to be bought. I’ve asked this more than once. One commenter told me darkly that all would be revealed in due course. (I’m still waiting.) The usual reason is some unspecified conspiracy by big business and government agencies, although again, it’s not at all clear what they’re getting out of it.

Unless, of course, the population is being dumbed down to blindly accept all sorts of attacks on our liberties. This seems to be linked to the fact that the tranquiliser prozac contains fluoride, & to the ‘Hitler/the Nazis used it’ meme – a claim, Ken Perrott notes, that was trotted out in the Hamilton City Council’s ‘tribunal’ on water fluoridation.. Unfortunately for this one, Hitler didn’t, & prozac contains much higher amounts of fluoride than town supply water would. (There have also been attempts to link fluoride with the nerve gas sarin; a sort of slur by association. Yes, there’s a fluorine atom in there. There’s also carbon, hydrogen, oxygen, & phosphorus: the formula for sarin is C4H10FO2P.)

Or perhaps it’s all a plot to reduce the world’s population! This one seems to be based on the observation that at high concentrations fluoride does affect the endocrine system: levels much higher than those found in town supply water. This means that fluoride’s hardly an effective tool for population control if no-one’s adding it at the requisite concentration. (China, with its one-child policy, doesn’t fluoridate at all, at least in part because in some regions water fluoride concentrations are already elevated.) This ‘theory’ is further based on major misunderstandings of work by John Holdren, who with Paul & Anne Erlich discussed the burgeoning human population & various actions that might curb its growth in the book Ecoscience: Population, Resources, Environment. At one point they noted that a population of around 1 billion might be optimal in ecological terms (we’re already at 7 billion & counting). This has been (mis)interpreted as advocacy for deliberately reducing the population to this level and, because of the known impact of high levels of fluoride on endocrine functioning, then gasp! fluoride must be part of the plot.

Ultimately, all these conspiracy theories require that an awful lot of people should be corrupt. Tens, perhaps hundreds of thousands of scientists, falsifying their research, hiding the bits that don’t fit the story, suborning new researchers as they come along. They’d have to be in every research institution in the world. It would cost ridiculously large amounts of money (money, in the case of fluoridation of water, that simply isn’t there.) Governments and the media would have to be in on it as well. And that’s not possible. Someone, somewhere, would provide evidence of what was going on.

And indeed, the various conspiracies can’t be all that good, if various brave mavericks are able to a) recognise what’s going on and b) spread their findings (on the internet & elsewhere) without the men in black turning up & carrying them away.



the male himalayan monal – an absolutely gorgeous bird Alison Campbell Jul 23

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Another for the ‘gosh, isn’t this beautiful?!’ files: the Himalayan Monal (the national bird of Nepal).

(Image via Facebook: Tambako the Jaguar; Flickr — with Robin SubbaSarvesh Wangawad,Jeriko AngueRoberto DelapisaJonas MgrNeelesh SuryavanshiShashank Asai,Sushant Bhujel and Pabitra Lamichhane.)

This stunning bird (Lophophorus impejanus) is a type of pheasant, and like other pheasants the species is strongly sexually dimorphic: the males are dressed in gorgeous irisdescent plumage, while the females’ plumage is dark brown apart for white patches on throat & rump, & the same bright blue circle round the eyes.

Such marked differences between the sexes are often due to intersexual selection, with females acting as the agents of selection & choosing their mates on the basis of physical appearance, or other attributes that give information on the male’s quality. The monal is a stand-out example of the eventual outcome.

Strongly dimorphic species are often polygamous – more usually polygynous, with dominant males mating with several females during the breeding season; phalaropes, however, are polyandrous, with the more brightly-coloured female laying eggs in the nests of several males and leaving them to incubate alone. In species where there’s little dimorphism, it’s often associated with monogamous breeding patterns, & as a general rule the type of breeding pattern in a given species is linked to the species’ ecology.


perhaps the most inspiring graduation address i have ever heard Alison Campbell May 21


At the recent graduation ceremony for students from Waikato University’s Faculty of Science & Engineering (& those from its sister Faculty, Computing & Mathematical Sciences), we were privileged to hear an absolutely inspirational address from the recipient of an honorary Doctorate at that ceremony: Dr Gordon Stephenson. And I mean, inspirational! After the event I spoke with Dr Stephenson & asked if he’d be willing to provide the text of his speech, because I believed it deserves the widest possible audience, and he was kind enough to provide me with a copy. (I’ve taken the liberty of adding a hyperlink in a couple of places, for those who may not be familiar with some of the references.)

Chancellor Rt Hon Jim Bolger, Vice chancellor Professor Roy Crawford, academia, distinguished guests, students at all levels, my whanau, everyone.

This really is an extraordinary and totally unexpected honour that you have bestowed upon me. I find it very difficult indeed to adequately express what it means to me.   

When my daughter Janet handed me the letter from the University on Christmas day, she says it is the only occasion she has seen me speechless. I was truly gob-smacked ! So I will just say ‘Thank you’.

It is actually somewhat ironic, because in the late 1940’s, as a returned serviceman, I took a BSc (Agric) at Reading University, England, and passed with a ‘C’ grade.

But life was too full as a student, what with sport, starting an agricultural journal, getting married to a beautiful civil engineer  graduate of London University, living on a small boat, and many other activities better left unsaid, such that the ambition to attain a First Class Honours degree went by the wayside.

I did, however, become infected with the stimulating topic of science. Even as a 10 year-old, I pored over nature magazines. I still have some of them.

But I left university puzzled. I had been taught things which just did not make sense, such as the idea that mountain formation was due to shrinkage of the earth’s surface, while the concept of so-called continental drift was anathema. And the explanations of  heredity were far from complete or even believable.

It got me thinking about ‘truth’ and the realisation that truth is only that which is the current knowledge and thought, and that it is constantly being replaced with new ideas. And where do ‘facts’ tie in with ‘truth’?.

We moved to Waikato in 1960, and I have followed with interest the development of this University from paddocks to a landscaped campus. Your reputation has grown, and you can now boast of being a leader among NZ universities in the particular disciplines you have chosen to develop. Congratulations.

Universities have critical roles in society.

Research is a heavy responsibility. It is actually a huge privilege to be paid to research. You are a repository of knowledge, not only in your libraries and theses, but also in the research-based understanding lying in the minds of academia.

Then there are your teaching responsibilities, hence all these wonderful students hopefully fired by your inspirational lectures. I know I was by some unforgettable tutors.

But there is another responsibility, which I often feel is not adequately addressed. This is the role of a university as the public conscience.

It has long perturbed me that the public battlers and advocates for a better society are almost all lay people or NGO’s, whereas those very issues are probably being studied in depth in this institution.

It takes courage to step out beyond the walls of the campus and into the hurly-burly of controversy. There are noble examples at this University, and they will know to whom I refer, but I’ll mention one from Waikato, the late much-loved Dr Charlotte Wallace.

Besides being an assiduous researcher of snails, she was totally fearless in her environmental advocacy, and greatly admired and respected as a result. She virtually started, decades ago, the South Auckland Conservation Association. She made a difference.

We look to the Universities to be the champions, the leaders, for the big issues facing us. You have the knowledge. Please, make sure it is put to good use.  

I turn now to you graduates of all disciplines and interests.

I was born in 1924 (I can see you all doing some rapid mental calculations). In that year, there were only two billion people on earth.

Now, in this one person’s lifetime, that has more than tripled. There are three people alive now for every one alive then. Picture if that were to happen to you all present here in the world of 2013. It would seem impossible.

So believe me when I say that maybe I can personally appreciate the creaks and groans of poor old mother earth, and the pressures and stresses placed upon the populace and natural systems.

There are the issues such as climate change, peak oil, the health of the oceans, extinctions and the loss of biodiversity, the rush to urbanization, rising sea levels, let alone the forecasted inability of farming to feed the projected ten billion people.

We ignore at our peril the intricate web of millions of species whose interactions create our living conditions. We have a lamentable inability to recognise the implications of exponential growth, and the menace of the bell curve. The downside of that curve will turn round and bite.

These matters are all interconnected, and cry out for solutions that are also interconnected. My generation has failed to find those solutions, or, where they are blindingly obvious, failed even more miserably to implement them.

Many of these issues were faced by Maori some 5-600 years ago. Their previously known world of easily harvested fish and birds suddenly faced the impacts of resource depletion. Their reactions paralleled those that arose centuries or millennia before in many parts of the world.

Their first reaction was war, to safeguard their food supplies and other resources. The other reaction, to their great credit, was to impose upon themselves strict rules of harvest, through such mechanisms as rahui. There are lessons there for humans everywhere.

And so I look to you, our next generation, to whom we dodderers bequeath our one-and-only beautiful and magical earth. In some ways, it matters little the topic you studied here.

You have, I trust, been taught by this University to think, because you will need to use those analytical skills that are so necessary in any field of study, for the massive tasks you face ahead. You have to persuade both the wider population and the decision makers, of the root problems we face. There are doubters galore, both for commercial and political reasons or because of reluctance to face facts.

The centuries-old saying is ‘There are none so blind as those who will not see’. You have an absolutely necessary task ahead, which may seem daunting, and you may react by thinking ‘what can little me do’.

However, I say you can make a difference. You will recall the butterfly effect, as expounded by Edward Lorenz, he of the chaos theory. He postulated that the effect of a beat of a butterfly’s wing in the tropics could trigger a hurricane many kilometres away.

I say to you, be that butterfly.

It is a sobering thought that you, we, are each utterly unique, an assembly of atoms never ever seen before. You will each therefore by definition, have abilities that are also unique. To make that ‘difference’ I speak of, you need to develop those abilities, and grow a fire in your belly, a determination to see things through.

Many of our gurus talk of the need to have ambition, but they are usually referring to the ambition to make money. While important, money does not equate satisfaction or contentment. Of its own, neither will it solve the problems you now face.

Nor will you achieve overnight success. It may take years, even decades. You’ll suffer setbacks, but that is in the nature of things, and our world needs stubborn battlers.

You will need to learn the skills of working with, rather than against, and of respecting the right of others to hold opinions that are so divergent from your own that they infuriate you. Anger is no solution. I think Churchill is credited with the saying ‘jaw-jaw is better than war-war’.

Seek friends, make alliances, and above all be positive. So often, even those who you originally felt were opponents, were actually just looking for solutions. Find those solutions.

Many years ago, a truth dawned on me. I had been used to complaining that ‘they’ should ‘do something’. ‘They’ frequently didn’t. I then realised that therefore ‘we’ must do something. Again, ‘we’ sometimes failed, and the clear conclusion was that ‘I’ must get stuck in. If I didn’t, why should someone else ?

Then something magical occurred. My actions suddenly activated the ‘we’, and in some cases, the ‘we’ became a reformed ‘they’. So I say, never be afraid to stick your head above the parapet.

Nor should you be put off by time. May I quote the proposed National Wetland Centre, at Lake Serpentine, south of Ohaupo. It is beginning to take shape, 16 years after planning started. Given maybe two more years, it could be completed.

And another issue took 67 meetings to end up with a solution that was welcomed by all parties. The Waikato Ecological Enhancement Trust was formed. It now puts hundreds of thousands of dollars annually into the wetlands and waters of the Waikato Catchment.

Stick at it !

To date, you have been absorbing, assembling, knowledge. Today, from this moment, your role changes. You have been learners, now, while still seekers, you become teachers. You have been followers, now you must become leaders.

Your collective tasks are frightening in their necessity. I challenge you. Get out there. Don’t be afraid. Be determined. Make sure our planet earth continues to be a place of diversity and beauty we can all truly love and protect. Play your part.

Then, when you reach the age of 80, people will say,’ yes, you made a difference’.

I end with a quote from the inspirational Helen Keller: deaf and blind from early childhood.

I am only one, but still I am one.

I cannot do everything, but still I can do something.

I will not refuse to do something I can do.


Thank you.

the gastric-brooding frog – not quite back from the dead Alison Campbell May 08

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I first found out about gastric-brooding frogs (Rheobatrachus silus) when reading Stephen Jay Gould’s essay “Here Goes Nothing” (as published in the 1991 book Bully for Brontosaurus). As he said, these frogs really do live up to their name: the frog

swallows its fertilised eggs, broods tadpoles in its stomach, and gives birth to young frogs through its mouth.

Gould’s tale first introduces another example of the ability of natural selection to shape truly strange behaviour: male Rhinoderma darwini frogs swallow the eggs they’ve fertilised and brood them, not in their stomachs, but in their throat pouches. These are the same pouches that male frogs inflate with air & use in croaking (& whistling, & chirping, depending on species) during courtship, which means that a brooding male is rendered voiceless for the duration. However, it doesn’t stop them feeding normally, something that was first demonstrated way back in 1888 by biologist G.B.Howes (Gould, 1991). I was interested to find out, while researching this post, that the eggs aren’t ingested immediately after fertilisation: they’re laid in damp leaf litter and the male remains close by, but waits until the embryonic tadpoles are wriggling around inside the egg membrane before taking them up in his mouth. (I’m guessing that the behaviour’s triggered by the sight of the wriggling tadpoles.)

As for the gastric-brooding species: Gould provides an engaging description of how this habit was uncovered. Until 1979

[n]atural birth had not yet been observed in Rheobatrachus. All young had either emerged unobserved or been vomited forth as a violent reaction after hatching.

However, scientists finally managed to get a gravid (I hope that’s the right word in these circumstances!) female in an aquarium with their cameras all at the ready:

The mother “partially emerged from the water, shook her head, opened her mouth, and two babies actively struggled out.”

It’s no small feat to incubate froglets in this way:

This… female, about two inches long, weighed 11.62 grams after birth. Her twenty-six children weighted 7.66 grams, or 66 percent of her weight without them.

And of course, the incubating female must stop eating and switch off production of gastric juices for the duration!

Sadly, confirmation of this highly unusual method of parental care was rapidly followed by news that the species appeared to be extinct in the wild. Which is why I was so intrigued by my student’s news of its resurrection. However, it seems that reports of that resurrection may have been somewhat exaggerated. A quick search turned up several articles (this one’s a good example) that describe what’s been achieved so far: R.silus tissues that had been in the freezer were thawed, and cell nuclei from those tissues were implanted in enucleate eggs from another, distantly-related, species of frog (an example of somatic cell nuclear transfer). Some of those went on to an early (but unspecified) stage of embryonic development before being frozen in their turn, to await possible reanimation in the future.

In other words, R.silus froglets won’t be hopping around just yet. (And I’m moved to wonder how achievable the aim of the Lazarus project actually is, as it relates to this species. After all, if the gastric brooding part is an essential part of development, where’s the stomach going to come from?)

S.J.Gould (1991) Bully for Brontosaurus. Penguin Books.

see-through creatures Alison Campbell May 08

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This is a ‘glass frog’ (image from National Geographic):

It’s one of a number of transparent or translucent creatures featured on the National Geographic’s “Weird & Wild” blog. (Actually I take issue with the Monarch butterfly image there, as strictly speaking we’re seeing a transparent pupal case; the butterfly inside is definitely not see-through.)

Glass frogs (Hyalinobatrachium pellucidum) are on the ICUN’s ‘red’ list as an endangered species, with habitat destruction the likely cause. However, if chitrid fungi are introduced to the frog’s limited range  - they’re recorded from only five locations on the Amazonian slopes of the Andes in Ecuador – then the population will likely decline even faster (always supposing this particular pathogen isn’t already there). These delightful little frogs are apparently about the size of a fingernail, & their translucency is due to a lack of pigment in the skin. Not only can you see the air-filled lungs, the red threads that are blood vessels, and the heart with some of the major arterial arches clearly visible – you can also see the animal’s skeleton.

And that reminds me: we were talking in class the other day about gastric-brooding frogs & one of the students said they’d heard that this species had been cloned. An intriguing possibility – I must go off & look into it!


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