Insect evolution

The Naked Scientists spoke to Dr Mike Majerus, Department of Genetics, University of Cambridge
20 November 2005

Interview with 

Dr Mike Majerus, Department of Genetics, University of Cambridge


A ladybird


Mike Majerus discusses the genetics of insects...

Kat - How similar are we to insects?

Mike - We're not very similar at all. If you look at our phenotype, which means the way we look, you can see we have a different number of eyes to some insects. We certainly have a different number of limbs. And yet when we go to the genetic level, we have an awful lot of genes the same. They're not exactly the same, but we can recognise that we have genes that do similar things. For example, we have very similar genes for respiration and DNA replication. In fact, for things like the genes for genetic replication, the similarities don't just stop at insects, but are found in pretty much all other forms of life.

Chris - If you look at something like a banana for example, I'm supposed to share about 60% of my genes with a banana. Would you go along with that?

Mike - Yes.

Kat - I'm getting images here of the film The Fly, where he wakes up and has turned into a fly. If you took a fly gene, would it work in humans?

Mike - That's the sort of question I'd really rather avoid, and I'll tell you why. There's this big feeling around the world that if the word genetics is mentioned, it's going to be something horrible. Most of the stories about genetically modified organisms are horror stories. Or there are mice with ears on their backs if we go back a decade or so. There's a phenomenal amount of genetics being done, but unfortunately you hardly ever hear about the good stories. There are two people I just want to mention. There's a guy called Dobzhansky, a Russian who went to America, and he said that nothing in biology makes sense except in the light of evolution. Then later, a couple of authors said nothing in evolution makes sense except in the light of genetics. If we're actually going to understand the world around us, we've got to understand genetics. It's the sort of thing that Darren's doing down at the Sanger Centre with his sequencing of vast amounts of DNA from different sorts of organisms that is beginning to give us a little bit of understanding of what's really going on.

Chris - Mike, you've also been doing some work on ladybirds. Apparently we've been invaded.

Mike - Oh yes. This is the killer Harlequin ladybird that arrived in the UK, and the first one was found on the 19th September 2004. It got into the press who made it into a very big story that it was going to wipe out all the British ladybirds. I'm responsible for that story. It's now increased its range so it's now all over the south east of England. We're getting huge numbers of records from the area that the Naked Scientists covers. We've had the first reports this autumn of houses being invaded by hundreds of these things. We've been working through the year and we've got funding for another year so that we can survey British ladybirds both where the Harlequin's arriving, and where it hasn't yet. We're doing genetics on this as well, as the Harlequin has lots of different colour forms. We're finding out the genetic control of those colours and we still want people to send us samples. If you can send us 40 or 50, we then get a frequency of the different samples and we can look at how evolution is affecting these colour patterns.


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