Descent with Modification by Natural Selection

Today we discussed how species evolve over time. Of the things we discussed in class we have now realized that species in the past were dramatically different than species from today.  We discussed the several theories behind the idea of how species have changed over time but we concentrated closely on Alfred Wallace and Charles Darwin’s contributions.  Wallace and Darwin are considered co-founders of the theory of descent with modification by natural selection.   While Charles Darwin was ravaging the seas and exploring the Galapagos Islands, Alfred Wallace was exploring wildlife in South America and Asia.  During these studies Wallace and Darwin corresponded with each other through the sharing of specimens and Wallace turned to Darwin for help in publishing his works in evolutionary processes.   Shockingly, Alfred Wallace’s ideas were a duplicate of Charles Darwin’s.  Although they were working on opposite sides of the world and had some correspondence with each other, their ideas were almost identical.  The concept is descent with modification by natural selection and it consists of 4 main components.

1.      Variation: within a population, the individuals possesses a multitude of different traits in physical appearances and behavior ( hair color, skin color, height).

2.      Inheritance: parents pass their traits to their offspring.  Some traits are more desirable than others based on other factors such as environment and resources.

3.      Over-reproduction: more offspring are produced than can survive. 

4.      Competition: offspring compete for resources and only the fittest survive and are able to reproduce passing on those desired traits to their offspring.  Individuals that posess less desirable traits typically do not survive and pass on their traits to their offspring.

These four aspects are intertwined to explain how species have changed or evolved over time.  Individuals within a species must survive long enough to compete for resources, reproduce, and pass on those desired traits to their offspring.  Those who do not survive will typically not reproduce and their traits become extinct.  For your review I want you to concentrate on the 4 aspects of Descent with modification by means of Natural selection: Variation, Inheritance, Over-reproduction, and Competition.  Make a mind map to help in your memory retention of the four aspects.  A mind map is a picture, diagram, organized drawing that helps you link the ideas and concepts to easy to remember pictures.  You can organize these pictures however you want but you may not use any words to demonstrate a concept.  Bring your mind maps with you to class and we will be discussing and comparing these concepts with each other.  Below I have given you some basic outlines without the pictures so you can get a visual of what a mind map would look like.  Again the only words you may use for this mind map is a title that states: Descent with Modification by means of Natural Selection.