Mutants in our Midst

The Body  Look around you! Every animal has certain anatomical similarities.  Among species, the arms and legs attach and move similarly.  Individuals of a species all move in similar fashions.  Frogs jump; whereas, humans walk.  While humans can also jump, can you imagine how tired you’d be if all you did was hop around all day?  These motions are determined by our anatomy.

Alert! MUTATIONS AHEAD! During the Industrial Revolution, dust from coal settled on trees, making them appear darker. The white colored pepper moth began to stand out on the trees.

Alert! MUTATIONS AHEAD!  When predators began eating the moths, they were easily visible.  Thus, the moths slowly started changing color to adapt to their new environment (to avoid being eaten!).  What had happened?

Mutations—What are they?  A mutation is a structural change within a gene or chromosome of an organism. This change results in the creation of a new character or trait not found in the parental type.

Mutations NOTE: The mutation is the change in the DNA. This can result in a change in physical appearance of the creature. So, an instance such as having extra body parts is not a mutation itself, but may be the RESULT of a mutation.

Mutations  However, like with the moths, a mutation may also result in an adaptation, such as a change in color or the shape or size of a body part. These finches from the Galapagos Islands all had different beaks to adapt to what food they could eat.

Not all mutations are bad!  Scientists now believe that the genetic variation found in all terrestrial life forms originally came from DNA mutations.  Genetic variations in a population allow natural selection to occur.

Be careful! Not all physical changes are the result of mutations!  Some physical appearances are the result of injury or trauma. We call these deformations.  Factors in the environment, like pollution can cause problems in development or growth. These problems can lead to a malformation.

Frog Life Cycle  Frogs and other amphibians have a life cycle that makes them very vulnerable to malformations.  Since they are undergoing constant anatomical changes throughout the first part of their life, they are very susceptible to factors that could cause change in their anatomy.

Comparisons MutationsDeformationsMalformations Always formed because of changes in DNA. Cannot be produced by changes in DNA. Can be produced by changes in DNA. Chemicals can cause a mutation if they alter the DNA. Chemicals cannot cause a deformation. Chemicals can cause malformations. Injury cannot cause a mutation. Injury can cause a deformation. Injury cannot cause a malformation. If a parent has a mutation, the child is likely to also have that same mutation. If a parent has a deformation, the child would not necessarily inherit the deformation. If a parent has a malformation, the child would not necessarily inherit the malformation.

Is more better?  You would think that having multiple legs would help the frogs jump better or that having more bones would provide better leg strength, but this unfortunately is not the case.  The extra bones disrupt the proper leverage that the normal bones would provide.

Is more better?  Extra limbs offset the natural balance and movement of the frog and are generally nonfunctional.  Also, the malformations are often just the tip of the iceberg when it comes to anatomical problems in the frog.

Can it happen to you? Many ecologists suggest that the same environmental changes that are causing gross animal malformations may eventually cause harmful health effects in the human population.