Basically, yes.  Dry ice doesn’t actually melt.  It sublimes straight to a carbon dioxide gas.  That takes energy so the more energy you can get into the dry ice the quicker it will sublime into nothing.  Something metal will conduct heat much quicker.  It’s something I’ve done in the past.  If you get a metal spoon and squash a piece of dry ice then it sublimes much quicker and you get lots of gas given out with a high squeaking noise.

We put this question to Dr Remy Ware:

Remy -  That’s a great question.  Indeed this crucial genotype-phenotype link is what we are after really in evolutionary genetics.  As yet we haven’t really looked in much detail at the genome of the Peppered Moth but what is quite comforting is that we have very good sequence data from related Lepidoptera species, such as the commercial silk worm Bombyx mori and also some of the papillary butterflies.  Their genomes are quite well-studied and it’s possible that we can look for candidate genes within those and transfer it.

A similar approach has been used in another species which shows melanism.  The rock pocket mouse which is a lovely little thing found in North America and you have a melanic variety of this mouse which rests on a dark surface produced by larval flow compared to the normal form which is a sort of fawn colour.  This species they’ve actually found the gene responsible for this polymorphism.  They’ve found the gene responsible for the melanism which is due to the melanocortin 1 receptor gene.  It’s this particular gene that’s mutated in that form of mice.  That’s an example where we do have this link between the genotype and phenotype.  That’s rather often used as a criticism of the Peppered Moth case in that it’s lacking.  The concept of being able to identify what’s going on genetically is really exciting.

Ben -  If I’m right genotype is what the genes actually show you and phenotype is what we see on the outside.  Phenotype would be the fact that it is a dark mouse.

Remy - Yes so a phenotype is produced both by the action of genes and the action of the environment.  The phenotype is sort of the physical manifestation of different factors causing a particular trait.  They are genetics and environmental factors.