Happenstance mutations matter

Scientists show that happenstance mutations matter

Finding: In experiments on bacteria grown in the lab, scientists found that evolving a new trait sometimes depended on previous, happenstance mutations. Without those earlier random mutations, the window of opportunity for the novel trait would never have opened. History might have been different.

Evolutionist Stephen Jay Gould once suggested that the if the evolution of life were “wound back” and played again from the start, it could have turned out very differently.

Though not firmly conclusive, the new research adds a real-world case study of evolution in action to the decades-old debate stirred by Gould’s thought experiment. British paleontologist Simon Conway Morris and others argued that only a few optimal solutions exist for an organism to adapt to its environment, so even if the clock were wound back, environmental pressures would eventually steer evolution toward one of those solutions — regardless of the randomness along the way.

What the scientists did
Scientists obviously can’t turn back the hands of time, but Richard Lenski and his colleagues at Michigan State University in East Lansing did the next best thing. Lenski’s team watched 12 colonies of identical E. coli bacteria evolve under carefully controlled lab conditions for 20 years, which equates to more than 40,000 generations of bacteria. After every 500 generations, the researchers froze samples of bacteria. Those bacteria could later be thawed out to “replay” the evolutionary clock from that point in time.

The evolution of a nutrient absorption ability
After about 31,500 generations, one colony of bacteria evolved the novel ability to use a nutrient that E. coli normally can’t absorb from its environment. Thawed-out samples from after the 20,000-generation mark were much more likely to re-evolve this trait than earlier samples, which suggests that an unnoticed mutation that occurred around the 20,000th generation enabled the microbes to later evolve the nutrient-absorption ability through a second mutation, the researchers report in the Proceedings of the National Academy of Sciences.

By way of contrast with another control group
In the 11 other colonies, this earlier mutation didn’t occur, so the evolution of this novel ability never happened.

Put populations in the same environment and see what happens
This is a direct empirical demonstration of Gould-like contingency in evolution. You can’t do an exact replay in nature, but scientists were able to literally put all these populations in virtually identical environments and show that contingency is really what had occurred.

What was the mutation that occured?
The next step will be to determine what that earlier mutation was and how it made the later change possible. If the first mutation didn’t offer any survival advantage to the microbes on its own, it would make the case airtight that Gould was right. That’s because a mutation that doesn’t improve an organism’s ability to survive and reproduce can’t be favored by evolution, so whether the microbe happens to have that necessary mutation when the second evolutionary change occurs becomes purely a matter of chance. Thus the first mutation must have improved the chance of the organisms survival.

The first mutation gave the microbes a survival advantage. The growth rate and the density of bacteria in the colony jumped up after the second mutation, but not after the first one. The first mutation may have set the stage for what was to come, the second mutation took advantage of the change.

Genes changes linked to an organism's survivability

Studies from biologists have found that a simple interaction between just two genes determines the patterns of fur coloration that camouflage mice against their background, protecting them from many predators. The work marks one of the few instances in which specific genetic changes have been linked to an organism's ability to survive in the wild.

What does the research show?
The work shows how changes in just a few genes can greatly alter an organism's appearance. It also illuminates the pathway by which these two genes interact to produce distinctive coloration. The result is that now there's reason to believe this simple pathway may be evolutionarily conserved across mammals that display lighter bellies and darker backs, from mice to tuxedo cats to German Shepherds.

What was studied?
Researchers studied Peromyscus, a mouse that is the most widespread mammal in North America. Within the last several thousand years, these mice have migrated from mainland Florida to barrier islands and dunes along the Atlantic and Gulf coasts, where they now live on white sand beaches. In the process, the beach mice's coats have become markedly lighter than that of their mainland brethren.

What did the research show?
Nature provides a tremendous amount of variation in color patterns among organisms, ranging from leopard spots to zebra stripes; these patterns help individuals survive. But it has been difficult to understand how these adaptive color patterns are generated. The research helped identify the genetic changes producing a simple color pattern that helps camouflage mice inhabiting the sandy dunes of Florida's Gulf and Atlantic coasts. These 'beach mice' have evolved a lighter pigmentation than their mainland relatives, a coloration that helps camouflage them from predators that include owls, herons, and hawks.

Previous research has shown that such predators, all of which hunt by sight, will preferentially catch darker mice on the white sand beaches, providing a powerful opportunity for natural selection to evolve increased camouflage.

Which Genes were involved?
Through a detailed genomic analysis, researchers identified two pigmentation genes, for the melanocortin-1 receptor (Mc1r) and an agouti signaling protein (Agouti) that binds to this receptor and turns it off. Conclusion: A single amino-acid mutation in Mc1r gene can weaken the receptor's activity, or a mutation in the Agouti gene can increase the amount of protein present without changing the protein's sequence, also reducing Mc1r activity and yielding lighter pigmentation.

Research findings
What do the genes do? Both genes affect the type and amount of melanin in individual hairs. If both genes are turned on, the mouse is dark in color. If a mutation occurs, which changes either gene this leads to a somewhat blonder mouse, but when the combination of mutations occur in both genes this produces a mouse very light in color.

Which came first? The Egg came first

This is one of those questions which is supposed to confound evolutionists because it gets to the heart of the matter so quickly.

Chickens lay eggs. Chickens come from eggs. Without the egg, there would be no chicken. Without the chicken there would be no egg.

So which came first? The chicken or the egg.

If the chicken evolved it had to evolve from something. But if that's the case, wouldn't it have evolved from an egg? But the egg already has all of its own genetic material so it couldn't have changed or mutated. It would be in a state of finality...so it can only produce one animal, the chicken. So the chicken couldn't have evolved from an other species only from the egg. And the egg already has all of the genetic material necessary to create a chicken. So the chicken and egg are already in their final states of development. Moreover, they are already in their first state of development. The chicken can only lay chicken eggs, the chicken eggs can only produce chickens. So there is no way that the chicken or egg could have evolved.

That argument only works because it assumes that the egg genetic material cannot be modified. The answer is that it can. There can be many contributing factors that mutate or change the egg. Radiation, external temperature variations, missing genetic cell instructions, protein development that did not work right, RNA carrying instructions that are not fully implemented in creating proteins. And if these variations continue over a long period of time a small instruction change can have large effects over time.

The egg is very fragile from an external point of view, but also internally. The chicken did come from an egg, but the first egg did not come from a chicken. No it came from an animal closely resembling a chicken, but the egg is a genetic mutation. And over a long period of time the egg's genetic material took on a form that we recognize today - the Chicken.

What this means is that over long period of time, there are no static life forms, all have the capacity to mutate and change.

For a different take see:
http://www.word-detective.com/howcome/chickenoregg.html