Tasmanian Devils And The Evolution Of a New Species Of Parasitic Tumour

Creationists love to misrepresent evolution and have an inordinate fondness for strawmen. These include:

1. Evolutionary change requires in increase in “genomic information”
2. Evolution only occurs within “kinds”
3. Speciation does not occur (incompatible with 2).

Number 1 would imply that genome size correlates with complexity. It does not. The largest known genome belongs to the single celled Amoeba dubia at about 600 billion base pairs. This is 200 times larger than our own genome. Even the lungfish Protopterus aethiopicus has a genome 50 times larger than ours. See here for phyletic comparisons .

This strawman also ignores the reality that some genes such as Abd-a can inhibit the development of complex structures such as abdominal appendages in invertebrates. Furthermore, subtle changes in regulatory sequences can affect morphological development that is controlled by genes already present. An example would be the expression of Bmp2 in the developing forelimb of bats .

One final problem for creationists is that natural or experimental deletions of parts (or the whole) of Alx-4 (loss of “information”) increases digit number in mammalian limbs – ie, less “information”, greater “complexity”.

Number 2 is just absurd as the spatio-temporal distribution of any number of transitional fossils shows. The creationist concept of “kind” is also confused.

Number 3. It happens! Deal with it creationists!

Now to the point, Jerry Coyne has posted this fascinating summary of work on tumours of Tasmanian Devils. It is significant because the tumours seem to have originated in an individual Tasmanian Devil and are now transferred from individual to individual by bite. Thus, making it a new species of parasite that is derived from the host species. It has obvious implications for all three points above. It is well worth a read.

The Platypus: Piss Poor Creationist Scholarship Or Wilfull Mendacity?

Platypuses (Ornithorhynchus anatinus) are excellent examples of primitive mammals that retain some reptilian features – such as egg laying. But, for some reason creationists seem to claim the platypus is a problem foe evolution. I often get this link thrown at me as if it proves that platypuses are a mosaic that contain parts from reptiles, mammals and birds, and therefore could not have evolved.

Let’s look at some of the creationist claims and expose more lies and misrepresentation.

1. It has a bird’s bill.

No it doesn’t! A bird’s bill is mainly made of the protein keratin. A platypus’s is leathery, flexible and contains numerous sensory pits

2. It lays eggs like a bird.

It may lay eggs, but they have leathery shells like reptile eggs. They are not surrounded by a shell like those of birds. This is what you would expect with the evolution of mammals: egg laying “reptiles” becoming egg laying mammals, which become live birth giving mammals. So, where is the problem?

3. It has a spur on its hind limb that produces a toxin similar to that found in reptiles.

Again, so what? That is what you would expect if they evolved from reptiles. In the link above, the author is also misleading. The platypus toxin actually evolved independently of the reptile venom. Both evolved from beta-defensin genes, but different classes of them , so although they are similar, there is no claim that one is descended from the other – that is creationists being naughty trying to play up the mosaic idea. The plan is to say Ha! Look they are almost identical to reptiles, but wait, they have genes found in birds too. Therefore evolution is wrong.

4. They contain genes for the egg protein vitellogenin. As the article claims, these genes are also found in fish and birds.

Again, we have some more naughtiness by omission. As the article is read, there is no mention of amphibians and reptiles. So, if it is not present in these groups, that would be a problem. Being a scientist, I’m not scared to make a testable prediction. I predict these groups contain vitellogenin genes (why don’t creationists make testable predictions? Answers on a post card). So, lets search the best database for finding peer reviewed scientific research publications (try it yourself). Let’s search for vitellogenin and amphibians. Well, no surprise there, 398 articles containing those key words, and plenty of papers on African clawed frogs (Xenopus laevis). What about searching for vitellogenin and reptile? This time, we get 62 publications describing its occurrence in snakes, crocodilians, iguanas and turtles. So, the evolutionary scenario of fish to amphibians to reptiles; which split into birds and mammals (via egg laying mammals) stays intact.

5. They contain ZPAX genes that are found in birds, amphibians and fish.

Note, there is no mention of reptiles here. That’s because they have not been looked for in reptiles – you won’t find it in pubmed. Here is another prediction for creationists, reptiles possess these genes – wait and see. The organisms that it has been studied in show a definite evolutionary relationship between groups, based on gene similarity see here.

6. Some of the sex chromosomes are like those of birds.

Platypuses have an unusual arrangement of sex chromosomes - there are 10 of them. They do follow the basic mammalian X Y sex determination pattern, with all X causing females and Xs and Ys together causing males. If they have evolved from reptiles, we would expect some similarities to reptilian sex chromosomes. Reptiles form 2 main groups when it comes to sex determination. Those were environmental factors determine sex and those where sex is determined by sex chromosomes (Z and W for female and two Zs for male). This is the system that birds have inherited. In the platypus, the Y chromosome seems to have evolved independently, with the X chromosome alone showing some similarity to both the reptilian and avian Z chromosome – from which it evolved.

7. They contain some avian like micro RNAs.

Guess what; at least one of the X chromosomes encodes some micro RNAs (see above).

Creationism has no evidence of its own and relies on dishonest misrepresentations and straw men concerning evolution.

I’m off to put some brights cards under the wipers of cars that have “you make Jesus cry” (puke-arama) stickers on them – again!