It may surprise you, but everything that has ever lived on this planet shares one thing in common: DNA. DNA, short for deoxyribonucleic acid, is a long molecule that serves as a blueprint for each individual organism. DNA is made up of smaller units, called nucleotides, that come in four different forms: A (adenosine), C (cytosine), T (thymine) or G (guanine). When strung together along a DNA molecule, the order of A,C,T and G’s create a complex code, called a genome, that carries the information necessary to build and maintain an organism.
Every time a cell replicates or an organism reproduces, its entire genome must also be replicated. Most of the time these nucleotides are replicated exactly, but nature isn’t always perfect. Every once in a while mistakes occur, and the sequence of A,C,T and G’s can change slightly. These changes to the genome are called mutations.
In The Evolving Project, you were tasked with replicating a Doodleplasm, just like your cells must replicate the order of A, C, T and G’s making up your genome. As you noticed, it was extremely difficult to perfectly trace the previous Doodleplasm, and some minor mistakes were made each time it was copied. Similarly, every time a genome is replicated it may contain minor mistakes, or mutations. On the results page you can see for yourself how these small changes can accumulate over time and lead to BIG changes.
Most mutations have a very small effect or none at all; however, over long periods of time, these mutations can accumulate and lead to large changes.
Big changes take longer, but small changes can happen in just a few generations. Drug resistant bacteria can evolve in a matter of days or weeks
When enough mutations accumulate, one species can split into two species through a process known as speciation. Once the two species become different enough from each other, they no longer reproduce together, and begin to evolve on two separate and independent paths. As you can see in the results, when a Doodleplasm species splits into two, both are very similar initially. However, as time progresses and each Doodleplasm acquires its own set of changes, they separate from one another and become different species.
The relationships between different species of Doodleplasms are represented in a diagram called a phylogenetic tree. By analyzing the differences in DNA between real organisms, scientists can discover the evolutionary relationships between species. Scientists use phylogenetic trees to show how these different species are related to each other. On these trees, splits in branches represent speciation. Species that are separated by less distance on the tree are more closely related to one another.
The process of mutation creates the raw material of genetic variation that other evolutionary forces, such as natural selection, act on. Although mutations themselves can occur randomly, they do not all have equal effects. Some changes to DNA may be beneficial, while others may be harmful. Mutations that allow an organism to better survive and reproduce in its environment are more likely to remain in the population, while mutations that are harmful are not as likely to be passed on to future generations. While the evolution of a Doodleplasm may seem simple, these same fundamental processes underlie the amazing diversity of life that we see on Earth today.