Tuesday, 1 December 2015

The Blue Tarantulas and the Stupid Designer

Singapore Blue Tarantula (Lampropelma violaceopes)

Source: Wikipedia
Blue reflectance in tarantulas is evolutionarily conserved despite nanostructural diversity | Science Advances

Imagine you're, say, a manufacturer of refrigerators and you've employed a designer to modernise your range. The basic technology is fine - things like the heat-exchange unit, door switch that turns the light on and off - and all you need is some styling to give your range more appeal in the prevailing market.

Now, what would you think if you found this designer was redesigning the heat exchanger or the coolant pump, not to make it any better - in fact some of his designs are worse than the ones you normally use - but because it hadn't occurred to him to use the ones you have in stock. In fact, he didn't know they had ever been designed before.

Well, okay, that's easily put right with a little education, so give the poor lad another chance. Possibly a little on the autistic side.

The next day, there he is again, designing something else to do exactly the same thing as the thing he designed yesterday. When you check you realise he hadn't even thought that if it did the job in one model it would probably do the job in a different one. At what point would you conclude that you hadn't employed a designer so much as a mindless idiot with an acute case of amnesia and a complete inability to think intelligently? You'd probably wonder how he managed to find his way to work each day without responsible adult supervision.

So, imagine how creationists have to cope with the realisation that this is exactly how their supposed intelligent (sic) designer works. The idiot keeps on designing different ways to do the same thing, some of which are worse than earlier designs!

Take these blue tarantulas, for example - and there are masses of similar examples in nature. Scientists from the University of California, San Diego, have just published the results of an investigation into how they got the blue coloration in their hair.

Slight shifts in arrangement within biological photonic nanostructures can produce large color differences, and sexual selection often leads to high color diversity in clades with structural colors. We use phylogenetic reconstruction, electron microscopy, spectrophotometry, and optical modeling to show an opposing pattern of nanostructural diversification accompanied by unusual conservation of blue color in tarantulas (Araneae: Theraphosidae). In contrast to other clades, blue coloration in phylogenetically distant tarantulas peaks within a narrow 20-nm region around 450 nm. Both quasi-ordered and multilayer nanostructures found in different tarantulas produce this blue color. Thus, even within monophyletic lineages, tarantulas have evolved strikingly similar blue coloration through divergent mechanisms. The poor color perception and lack of conspicuous display during courtship of tarantulas argue that these colors are not sexually selected. Therefore, our data contrast with sexual selection that typically produces a diverse array of colors with a single structural mechanism by showing that natural selection on structural color in tarantulas resulted in convergence on similar color through diverse structural mechanisms.

Blue reflectance in tarantulas is evolutionarily conserved despite nanostructural diversity
Bor-Kai Hsiung, Dimitri D. Deheyn, Matthew D. Shawkey and Todd A. Blackledge
Science Advances, 27 Nov 2015 : E1500709; DOI: 10.1126/sciadv.1500709

*Copyright © 2015, The Authors. Reprinted under terms of Creative Commons Non-Commercial licence (CC-BY 4.0)

There is strikingly little variety in the shade of blue produced by different species of tarantulas. We see that different types of nanostructures evolved to produce the same 'blue' across distant branches of the tarantula family tree in a way that uniquely illustrates natural selection through convergent evolution.

Dimitri Deheyn,
Scripps Oceanography and coauthor of the study
Each of these five species of tarantula produces an almost identical, non-iridescent blue colour without pigments and which don't change when observed from different directions, as iridescent colours would. And they each do it differently.

That's right. To believe in an intelligent designer, you have to believe that, like our refrigerator designer, it has designed five different ways to do the same thing in creatures which are basically very similar to each other, and have very similar genomes as a starting point. It's exactly like there were five different 'designers', neither of which would speak to each other and each of which closely guarded its design and refused to share.

The reason it looks like that, of course, is that that's exactly how the 'design' process worked. The design process was nature selecting from amongst minor variations over time, each iteration producing something that made the particular species just a little better able to do whatever blue coloration enables it to do. These five evolutionary processes converged on a single outcome by five different routes because the environment isn't bothered about how something is done but only with the fact that it is done.

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