December 4, 2008

Cane Toad Evolution: The Good, The Bad, And The Ugly (and The Funny)

It was over 70 years ago that cane toads were introduced to Australia from Hawaii as a way to try to take care of the cane beetle who were agricultural pests. But:

The plan backfired completely and absolutely. As it turns out, cane toads cannot jump very high, only about two feet actually , so they did not eat the beetles that for the most part lived in the upper stalks of cane plants. Instead of going after the beetles, as growers had planned, the cane toads began going after everything else in sight--insects, bird's eggs and even native frogs. And because the toads are poisonous, they began to kill would-be predators. The toll on native species has been immense.

The Good
The cane toad is probably one of the best ways to see evolution happen before our very own eyes, which means that they can be used as PROOF that evolution does happen.

The legs of cane toads have increased by 10% since arriving. Note: there are still toads with shorter legs, but the ones that are on the migration front have the ability to travel more ground per day thanks to their bigger legs.

Now, I know evolution deniers will always say that they have no problem with this kind of evolution. However, evolution is evolution is evolution. The genes of these toads have changed. And if there is still an argument the best thing to do is to ask the denier "now that you agree that evolution happens, what mechanism prevents evolution from making lots of small changes which appear like big changes over lots and lots of time?"

Evolution in fact, is happening too fast for these toads. One in ten are developing arthritis and back defects because their bodies were not made for the size of their legs.

The toads with the smaller bodies seem to be more equipped to live longer and breed more.

The flawed toads may continue to breed their bad lineage if they do in fact make it past toad puberty and are able to make new tadpoles. So we could see a higher percentage of hunchback toads in the near future. But if they wind up overpopulating their ecosystems where no more land is available, the small bodies toads will be the one that survives in the end.

There is also a problem with the immune systems of the toads who get arthritis. Again, this trait could go on if they are able make it to procreation.

There still have a lot of ground to cover before they make it all across Australia, so I don't see the arthritic toads dying out so fast.

Another cool thing is that many other animals are evolving because of the presence of cane toads. Some snake species have evolved smaller jaws so that they can't swallow these poisonous treats even if they wanted to. Of course, this means that the snakes with bigger jaws had a trait that was destined to wind up in the evolutionary trash bin. The toads helped kill off those who had the trait in a very short period of time.

Also, many other animals who were attracted to eating cane toads, are not anymore. Again, this is due to the innate mechanism that tells one what is food and what isn't, evolving to help the species survive. Again though, the animals with the attraction to cane toads helped their line out by dying before procreating too much. The animals without the attraction trait had a better chance of surviving to procreate more. That is evolution 101 to any of my Fundy readers.

The Bad

As stated above, these toads are taking over. They are poison to eat. Pets die when they eat these guys. They are also killing off endangered crocs and quolls (whatever the heck a croll is).

There are papers that give me a headache to read that predict cane toads will wind up living all over Australia.

There were only 100 or so that were introduced in 1935. Now there are over 200 million of these creature.

Besides being able to get high off their poison (Family Guy had an episode having to do with licking cane toads), these amphibians have an average life span of 10-15 years. That is the same as dogs (which I find totally unfair, if there was a God, dogs would live to 80). In fact, they can live up to 20 years in captivity.

The Ugly

In order to get rid of cane toads, Australians have come up with a couple of gruesome ways. The first one is to refrigerate the cane and then freeze it to death.
If you think that is humane, you haven't seen anything.

Cane Toad Golf

I could never ever do that. I agree that cane toads need to go, but there has to be a better way.

The Funny