Watching Evolution in Real Time

Every now and then, in music, an album comes along, or I find an old one, that contains songs that seem so perfect in concept, arrangement, execution and delivery, that for the entire package to exist seems so obvious. As in, why didn’t anybody think of that before?. Nirvana’s Nevermind is one example; such a full-on blast-out of messy rock (albeit highly produced) that dealt with young adult alienation so perfectly that the singer, in a fog of an undiagnosed mental illness, succumbed to the misery and despair of his lyrics and committed suicide.I was 18 when I first heard the opening strums of Smells Like Teen Spirit while wandering around a small record store (remember those?) in 1991. I thought “Yeesssss, finally!!!!”.  So, this is what it was like to hear The Sex Pistols for the first time in 77’, when I was only 4. Actually, Never Mind the Bollox is another one. An “I wish I thought of that” moment.

And so too in science sometimes along comes a report of the most perfect piece of research that makes the reader think; “Damn!! Wish I though of that”. If I was a working biologist, that is.

To conduct the first most complete study of evolution to date, a team of ingenious biologists have gathered data that illustrates the process of natural selection in real time (link). Never before have biologists so comprehensively linked the evolution of camouflage with survival. We know about it, through a series of very solid theories, but this is the first time it’s been proven with observational data.

Using mice, they have tracked the role fur colour plays in survival against naturally occurring predators. Using hundreds of wild caught mice, they placed them into large enclosures set up in the wilderness in Nebraska. Different enclosures had different soil types – sand, clay, dark soils etc. The mice were then left alone, save for around the clock maintenance of the experimental enclosures, which apparently was substantial.

Three months later, after exposure to naturally occurring owls and other predatory birds, the biologists returned to assess the mice populations. They found that the surviving mice in the lighter coloured enclosures, those with sand and light-coloured clays, had lighter coloured coats that matched their environments. The same was observed in the dark enclosures – the survivors possessed darker coats. That, in itself, is an interesting, and significant, biological observation. But the team also sequenced the DNA of a gene involved in fur colour in mice known as the Agouti gene. They discovered that at least seven mutations were more prevalent in the lighter coloured mice than the dark coloured mice.  Here was scientific proof for the role of genetics in natural selection; that genes are crucial for the survival of an organism against natural selecting forces thus driving biological change as inferred by particular advantage.

To me, this is a beautiful and simple work of genius (like the perfect pop album). But they dug even deeper to add layers of intellectual complexity to give the work depth (like, for example, the best of drone rock albums). Like all genes, the Agouti gene cannot work alone if it is to produce the yellow brown pigment that confers darker fur colour in mice. Genes work in tandem with many others to produce whatever it is evolution programmed them to make. In this case, the researchers discovered that the mutations switched off the ability of the Agouti gene to cooperate with the other genes in the genomic concertina of fur pigment production, and so lighter coloured mice are the result.

In the enclosures with lighter soils these mice were less likely to be picked off by aerial raptors. In the enclosures with darker soils, the lighter coloured mice were the most likely to be predated upon by owls.

One can confidently surmise that those lacking mutations would produce offspring that also lacked the Agouti gene mutations; baby mice with darker fur, that blended into the background of those particular dark enclosures more effectively. The prevalence of the mutations (or lack of) in the Agouti gene has not yet been reported for subsequent generations of mice that emerged from this work, but since this experiment is ongoing (it has been on the run for almost ten years at this point) such publications are not far behind, I would confidently venture to guess.

Photo by Credit: by www.pexels.com

 

 

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