Evolution & Biological Classification TSW Identify & describe the selective forces that “drive” evolution TSW Describe natural selection & its role in evolution

2 Goals for ALL living things Survive and reproduce All behaviors/morphology/physiology are geared or “adapted” to meet these goals

Where do we “Get” these traits? Nature: We are born with these-genetic make-up coded in our DNA from our parents to distant ancestors Nurture: We are taught directly or indirectly by our environment & our experiences

How do we know that organisms have evolved? Look at fossils for comparative anatomy Look at biochemistry for comparative processes Look at molecular biology for DNA sequences

Evolution The process by which the genetic compositions of POPULATIONS of organisms change over time Evolution does NOT happen to INDIVIDUALS

Genetic Mutation The raw material of evolution which is acted on by natural selection

Natural Selection Process explaining why organisms that possess variations (mutations) that are best suited to the environment will be most likely to survive and reproduce

4 Premises of Natural Selection All organisms produce more offspring than can possibly survive to reproduce There is a great deal of variation in traits among individuals in natural populations, many of which can be inherited

4 Premises of Natural Selection 3. Resources (food, light, space) are limited, therefore, there must be competition 4. Individuals with traits better suited to their environment survive to reproduce more of their kind

Traits Not all traits are good, some are just “along for the ride” because they are “linked” to beneficial traits Some are neutral- they don’t carry an advantage or a disadvantage…they are just there