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Peter K. Dearden

I was recently asked why I work on honeybees, especially given my growing intolerance to bee stings. There are lots of easy answers to this questions, including how cool they are, how important they are, how remarkable their biology is etc etc, but when it comes down to it, there is a real answer. So just to see how strange scientist’s career pathways can be, I want to tell you how I came to be a bee biologist. To find out, we have to go back 540 million years…

If you are not a biologist, or even if you are, you might not have heard of the Cambrian explosion. This is a tragedy, because something remarkable happened, which echoes through evolutionary history. Geologists often divide up periods of geological history using key fossils as signatures of particular geological epochs. One of the biggest divisions is between the Precambrian, and the Cambrian. Most of our planet’s 4.5 billion year old history fits in the Precambrian, but around 560 million years ago, there is a sharp discontinuity, and the Cambrian starts. The discontinuity is that, in most places, there are no fossils in Precambrian rocks, but there are tons in the Cambrian. It is if in a blink of time, animals with hard shelly bits, which fossilise easily, evolved. This is the Cambrian explosion. Suddenly animal life seems to have gone from nothing to something that produced hard bits that turn up as fossils

In 1907 a geologist in the Canadian Rockies, Charles Dolittle Walcott, made a remarkable discovery; fossils of the soft bits of animals, which subsequently came to be known to date from near the Cambrian explosion. Suddenly we had the possibility of understanding what these first animals might be. Now the story of the Burgess shale fauna is too big for this blog, but go and look at the fossils at the Royal Ontario Museum website. We now know that this fauna is found in a few places in the world, and that there are animal fossils in the Precambrian, but they are weird.

If you want to know some of the story, go and read “Wonderful life” By Stephen Jay Gould, but realise that the interpretation of the meaning of the fossils is disputed by others (see for example here). It looks as if this first animal fauna not only had examples of the Phyla of animals living today, but also some very strange looking animals that look like nothing on earth (g and look at that one, its awesome).

When I was an honours student at Victoria University, ‘Wonderful life’ was set as a reading, and the equally wonderful Dr Geoff Rickards set an essay question asking us poor students to answer the question if normal evolutionary processes could explain the sudden appearance of the Burgess shale animals.

My idea was that they could, but that the different shapes of the burgess shale animals came about because they had a very plastic developmental system, which allowed for lots of morphological diversity without much genetic change. Hence this diversity could have evolved very quickly, because of flexible developmental programmes. Not a terribly original idea, but one that got me thinking about how you make an animal, and how much genetic change you need to make that animal a different shape.

Now we know more. We know that some of the weirder Cambrian animals are intermediate forms between living groups, and it has been proposed that the history of these animals may be quite a lot older that their fossils suggest. Perhaps these animals didn’t evolve quite so rapidly. But my question remained, how much genetic change do you need to have morphological change?So I went and studied how morphology is made in an animal, and how those mechanisms that make morphology differ between animals; always circling, but not answering, the question.

Then, when looking for new research directions on returning to New Zealand, I realised that the way to answer to this question was staring at me in the face. There are animals that produce morphological change WITHOUT ANY genetic change. Most of these are insects, and the phenomenon is known as a polyphenism. The coolest polyphenisms are in bees and wasps, and the easiest to study is in the honeybee.

Honeybee females are either workers or queens. That doesn’t really get across how different workers and queens are. They differ in shape, morphology, size, behaviour, brain function, ovary activity. They are different. But that difference isn’t genetic, it is due to what larval bees are fed. Larvae fed royal jelly become queens, those not, become workers. The environment can radically change the morphology of these animals, without any genetic change.

We have been studying this phenomenon for a few years now, with the support of the Marsden fund and Gravida, and have recently published our first paper describing what Royal Jelly does to the honeybee genome (don’t download it yet, BMC have mangled the figure legends and I am waiting for them to fix them).

So that’s why I work on bees. Because of the Burgess shale fauna, and Stephen Jay Gould, and Geoff Rickards and because frankly, bees are really cool (and important).