Monday, 31 July 2017

Unintelligent Design - Silly Goose!

I took this photo today, in a park in Oxford. It shows why intelligent design is a stupid idea.

The white goose is almost certainly a hybrid between an Egyptian goose, Alopochen aegyptiaca, and a feral domestic goose. Domestic white gees in Britain are mostly a variety of greylag goose, Anser anser domesticus, so this strange looking goose is a probably a hybrid between the Egyptian and the greylag goose. The give-away is the strange-looking eyes that look spectacled from a distance, the pale brown wing feathers - not obvious in this photo (this one wasn't completely white) - and the long, pink legs.

It is highly unlikely that this was simply a leucistic Egyptian goose. It was also on it's own, not with the typical small group that Egyptian geese are normally seen in. Egyptian geese are believed to be related to the shelduck and so come somewhere between the ducks and geese. They were introduced as an ornamental bird into the UK and have become established in Norfolk, the only place I have seen them before. They have since spread to the Thames Valley (my son has seen them on the Thames).

Incidentally, the other geese in this photograph are Canada geese, an introduced species that has become widespread and which also interbreeds with 'local' geese.

But why does this show how intelligent design is a stupid idea?

To understand that we need to understand how and why the geese and ducks hybridise regularly, especially when in close proximity as in water parks. And to understand that we need to understand how related species normally establish barriers to hybridisation once it become a significant disadvantage to inherit mixed characteristics. These barriers come in two forms:

  • Pre-zogotic barriers, where there are mechanisms preventing sperm and egg coming together. These can be mating rituals, female sex selection, physical incompatibility (mating is physically impossible), etc.
  • Post-zygotic barriers, where the result of fertilisation can't develop into a viable, fertile adult. It either fails to develop or the offspring is infertile. Mammals have an additional mechanism in that a female's immune system might be able to recognise and attack a developing 'foreign' embryo but birds, where the product of fertilisation is quickly encased and expelled from the body, do not have this mechanism available to them. Hence, birds are much more dependent on pre-zygotic barriers.

Egyptian goose, Alopochen aegyptiaca
We also need to consider the breeding strategies employed by male and female geese. Essentially, we have an arms race between males and females where females benefit from controlling who the father of their offspring will be and the males who benefit from mating with as many females as possible. This difference in reproductive strategy comes from the fact that females, who produce a relatively few eggs, invest a lot more in those few eggs than males do in the millions of sperms they produce. Females go for quality; males for quantity.

A second strategy females can employ is the cuckoo strategy - laying her eggs in the nests of other geese. Goslings are self-feeding from hatching so it doesn't matter what the parent who rears them is feeding on; all they require is warmth and protection. But, they imprint on the parent who rears them so they 'regard' themselves as the species that rears them, not the species that produced them.

Males, on the other hand, as well as fighting off rival males and mating with females who 'select them' consensually, also use a rape strategy. Sex between ducks and geese is often forced and they are the only group of birds to have retained a penis, probably for this very reason. Males benefit by mating with any available female.

Domestic greylag goose, Anser anser domesticus
Lastly, we need to understand the chromosomal arrangement of the ducks and geese. For reasons which are unclear, the number of chromosomes and the arrangement of genes within those chromosomes is remarkably stable in birds. Mammals typically have between 18 and 30 pairs of chromosomes but birds almost always have between 38 and 40 pairs - a much narrower range. All the geese have 40 pairs.

So, we can have a goose who thinks its a different species, mating with a goose it has ether selected or been raped by, producing a viable hybrid.

Now, you would think an intelligent designer who designed all the different species of goose would not need to have designed barriers to hybridisation in the first place, but the creationists' putative designer seems to have designed barriers that don't work. Curiously, it seems to have designed breeding strategies which positively facilitate getting around any barriers and ones which seem to have ignored what creationists claim - that this same designer intends each and every individual to be born - so why so many wasted sperms? Why haven't males and females made the same investment in their gametes if the two which come together have been predetermined?

All in all, this doesn't seem a very intelligent thing to do, does it? Could it be that the problem we have here is that not very intelligent people who are ignorant of the subject, or the frauds that dupe them, have inadvertently defined 'intelligence' so it includes sheer stupidity?


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