The Evidence of Evolution in .NET framework

Paint QR Code 2d barcode in .NET framework The Evidence of Evolution

Evolution is simply the change over time in the frequencies of different heritable traits (that is, the frequencies of different genes) in a group of organisms One year, half the birds have blue eyes and the other half have brown Some years later, two thirds of the birds have blue eyes If eye color is a heritable trait, that is, one that is passed from parent to offspring, then that change is evolution Darwin s big idea was coming up with a process that could cause these changes This theory of natural selection is simply a process in which heritable traits that help an organism survive in its current environment occur more frequently in subsequent generations In other words, genes (the heritable traits) that are favored (help survival) increase over time Evolution by natural selection really is that simple, regardless of what you may have heard to the contrary Darwin, the father of evolutionary theory (refer to 1), did a phenomenally good job of piecing this part of evolutionary process together, but he could only hypothesize about the underlying details of what he called descent with modification What he didn t understand was the underlying genetic mechanism that was responsible

Making out heritable traits just requires knowing a little bit about DNA, genes, and the genetic code topics covered in more detail in 3 This knowledge of genetics allows researchers to measure gene frequencies Today, scientists can do more than just observe that evolution has happened; instead, they can determine the specific genes involved and measure the rates at which the genes frequencies change in populations where different selective forces are at play Scientists knowledge of exactly what is going on gives them a much richer understanding of the process and allows them to ask far more detailed questions than Darwin could

Darwin saw evidence that the process of natural selection had occurred in nature, but he was unable to watch it happen Scientists today, however, can actually observe the evolutionary process in action Using organisms that reproduce rapidly and can be kept in laboratories in large numbers (such as fruit flies and bacteria), and employing modern tools and techniques (such as DNA sequencing), evolutionary biologists can conduct actual evolution experiments and watch the results Scientists don t pick fruit flies because anything about that species is special; they pick fruit flies for expediency Experiments conducted with fruit flies go a lot faster than experiments with other organisms (such as dogs or sea turtles) because the generation time of the flies is much, much shorter A fruit fly is born, reproduces, and dies within a couple of weeks This short life span gives scientists more opportunity to examine changes in heritable traits

Scientists can measure the rates at which evolutionary changes happen By measuring changes in the frequencies of existing genes and observing mutations, they can describe the evolutionary process exactly They can see in the laboratory how selection can result in changes in gene frequencies Here s a favorite example of mine to show how witnessing evolution in action is possible: antibiotic resistance Scientists can observe how the frequencies of genes that make a microbe resistant to antibiotics increase when the environment changes to include an antibiotic They take a beaker full of microbes and add some antibiotics Then big drumroll here they come back the next day and find that the frequency of genes conferring resistance to antibiotics is much higher than it was before the antibiotics were added Why Because all the bacteria that didn t have antibiotic-resistance genes died and the ones that

did have antibiotic resistant genes reproduced a lot! Hence, the favored trait resistance to antibiotics increased over time You can read more about antibiotic resistance in 17 Mutations don t occur in response to environmental change Instead, the mutations already exist and are favored in the new environment Beakers full of bacteria tend to contain mutants that are resistant to antibiotics even when no antibiotics are around Toss an antibiotic into the mix, and the mutation gets its chance to shine by enabling the bacteria to survive in the presence of the antibiotic