The Role of Genetics in Parallel Evolution

There are two things to consider about the role of genetics in parallel evolution.

The first is that the genetic code for a given species may contain the potential for many complex structures that aren't actually expressed in that organism. Imagine a construction crew building a house. The blueprint may contain the instructions to build an addition on the back of the house, but unless the architect tells the crew to build that part, they'll only build the basic house, without the addition. Our genetic equivalent to the architect would be another mutation that activates the portion of the DNA needed to actually express a trait.

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Jellyfish have a radial body plan, but their genes contain code for a bilateral body plan.

Jellyfish and anemones are animals with a radial body plan -- they have no left or right side. However, their genetic code has been found to contain a marker for a bilateral body plan [source: Ars Technica]. For some reason, it isn't expressed in members of the jellyfish family.

Why is this important for parallel evolution? It shows that very primitive organisms can have the genetic tools available to create greater complexity. As the organism evolves, widely separated species can develop similar traits because the potential for those traits was there right from the beginning.

The second thing to consider is the experimental evidence. Recently, biologists have gone beyond morphology in their examination of parallel evolution. They have found proof that in at least some cases, morphological similarities were matched by genetic similarities. The chemical interactions of proteins and amino acids that cause the morphological changes were also the same in two species that had been isolated from each other for millions of years [source: ScienceDaily].

More Convergences The thylacine, also known as the Tasmanian wolf, is often used as a prime example of convergent evolution. Now extinct, the thylacine occupied the same ecological niche as canine predators in other parts of the world. Despite having almost no evolutionary relation, thylacines and gray wolves have very similar morphology, are roughly the same size and share many features. You can probably see an example of convergent evolution right outside your window. There are tens of thousands of species of plants, many of them unrelated to each other. Yet plant species worldwide have evolved leaves. While leaves come in many shapes and sizes, we all know a leaf when we see one, because they’re all so similar. There are certainly cases of divergent leaf evolution (pine needles, for example), which only makes it all the more fascinating that so many species evolved leaves that look the same.

If you want to learn more about evolution, natural selection and animals, try the next page.