Survival of the fittest is one of the key tenants in the Theory of Evolution. But how much "fitness" must an animal have in order to be successful? For the first time ever, scientists have measured the evolutionary selection of the fittest.
In the Theory of Evolution, the fittest individuals of each generation survive in order to reproduce and pass on their traits to the next generation. This can explain the myriad unusual traits that animals have developed over time. For example, it explains how cheetahs can run so fast and certain patterns that coloration that animals express in their fur and feathers. But how do you determine how fit an animal must be to survive?
In this latest study, the researchers looked at the bacteria Salmonella to measure the power of natural selection. This bacterium competes for food and is under intense selection to use food to grow faster than other individuals in the same location.
In order for the bacterium to grow, it needs to translate its genetic code into amino acids that come together to create proteins. The speed of this translation determines just how fast the bacterium can grow. This genetic code, though, has several different codons that can be translated into any one amino acid. In this latest study, the researchers looked at whether it mattered which particular codons were used to create EF-Tu, which is an extremely important protein for the bacteria.
In this latest study, the researchers changed many different codons in the bacterium to find out. They found that changing even a single codon reduced the likelihood that the bacterium would survive.
After finding this out, the researchers mathematically calculated this fitness cost. They found that changing a single codon reduced the fitness of the bacterium by .01 percent per generation.
So what does this mean? It shows that even tiny changes in fitness can cause an animal to fail evolutionarily. In other words, animals walk a fine line between success and failure. If they're not fast enough, not strong enough, or not big enough, it's likely that they won't pass their traits along to the next generation.
The findings, published in the journal PLOS Genetics, also show how evolution can select tiny differences that can make big changes in an organism over time. This, in particular, gives researchers a clearer view of the process of evolution.
