LT- Today, I can compare and contrast the two proposed theories of evolution from the 1800s to determine which one is valid by writing a critique of the invalid theory. Essential Question: How does life on Earth continue and adapt in response to environmental changes? What are the two proposed theories of evolution? Which theory is accepted today? Do Now: What is the difference between a law vs a theory?

What two things cause change and variation in organisms? Mutations and sexual reproduction. What is an inherited trait vs an acquired trait? An inherited trait is a trait that is passed down from parent to offspring through germ cells (sperm and egg) and is present in all of the individuals chromosomes. An acquired trait is a trait that has been changed or altered by the environment and is not present in all of the individuals chromosomes. examples: a sun tan, building muscles at the gym, cancer from UV radiation. What is evolution? Evolution is the change of species over time.

Theory #1 A trait that is needed in an environment will be used and enhanced. That trait that is needed in the environment will be passed on to offspring and it will be further enhanced with each generation. Over time that trait will continue to be enhanced and it will be present in all members of the population.

Lamarck’s Theory of Evolution A new trait will occur due to its need in the environment. A trait that is used and needed in an environment will be enhanced. The enhanced trait will be passed onto offspring and over time will continue to be enhanced as it is used.

Theory #2

Darwin’s Theory of Natural Selection Overproduction A species produces more than can survive Variation There are differences within the species Selection Organisms with the traits that are more suitable survive more frequently and pass on those traits Adaptation The traits of those that survive and reproduce will be occur more in future generations

Darwin’s Theory of Evolution A new trait will occur randomly (this we now know is due to mutations). Variations that make the individual more suitable for the environment will allow them to survive. Individuals with the suitable trait will reproduce more and over time that trait will show up more frequently.

Darwin’s Theory of Evolution Natural Selection Overproduction- a species will produce more offspring than a population can support. Variation- within all species variation in traits occur. (we now know that these variations (new traits) occur due to random mutations). Selection- based on the environmental conditions, some traits are suitable for survival. Adaptation- over time the occurrence of the needed traits will become more and the unneeded traits will become less.

Time- Time is crucial in both theories Time- Time is crucial in both theories. In Lamarck’s theory, it takes many generations for a trait to be enhanced. In Darwin’s theory, it takes many generations for the variations that are not suitable to evolve out. Environment- The environment is crucial in both theories. In Lamarck’s theory, the environment forces certain traits to be used and certain traits to not be used. In Darwin’s theory, the environment selects the suitable traits for survival. New Traits- In Lamarck’s theory, a new trait is acquired by using it. In Darwin’s theory, a new trait comes to be through mutations (Darwin did not know this at the time, he just knew that variation was natural)

Darwin’s theory of evolution is the theory that agrees with modern day genetics. Darwin’s theory states, that all species can produce more members than a given environment can support and “within every population there is variation amongst members of the species.” Although Darwin did not know what causes variation because he did not know about DNA, his theory accurately depicts that there are some variations (which we now know are caused by mutations) that make certain members of a species more suitable for survival. Therefore, they will reproduce more and their variation of traits will be more common in future generations.

Lamarck’s theory of evolution is the theory that does not agree with modern day genetics. Lamarck’s theory states, “characteristics that are used are needed for the survival of the organism therefore they will improve over time due to their use.” These traits will continue to be enhanced over time and increase in the frequency that they show up. Although Lamarck was correct in stating that we can improve a trait in our lifetime, he did not know that these traits are acquired traits and are not present in the chromosomes of our sex cells, therefore we cannot pass these traits on to our offspring.

The Galapagos Islands Where are they?

How does evolution into a new species occur?

The carrying capacity is the largest population that an environment can support at a given time. Birth rate- the number of births Death rate- the number of deaths What happens if the birth rate exceeds the death rate? What happens if the death rate exceeds the birth rate?

The S-shaped pattern in which the growth of a population typically slows down as it approaches carrying capacity. The J-shaped pattern in exponential growth indicates the development at an increasingly rapid rate in proportion to the growing total number or size