Chapter 6: Change Over Time Lesson 1: Darwin’s Theory Cells and Heredity Chapter 6: Change Over Time Lesson 1: Darwin’s Theory

Charles Darwin Studied in the Galapagos Islands Saw a variety of living organisms and compared them to organisms from around the world.

Charles Darwin Convinced that a species changes over time. Species: group of similar organisms that can mate with each other (more than 1.6 million species). He mostly studied tortoises and birds.

Charles Darwin Darwin thought that all finches must be related through a common ancestor, and that the changes they had in their beaks was a result to the environment. Adaptation: a trait that increases an organism’s ability to survive and reproduce.

Charles Darwin Darwin came up with a hypothesis of evolution: the process of change over time. He thought species change over many generations to become better adapted to new conditions.

Pope Francis “When we read in Genesis the account of Creation, we risk imagining that God was a magician, with such a magic wand as to be able to do everything,” he said. “However, it was not like that. He created beings and left them to develop according to the internal laws that He gave each one, so that they would develop, and reach their fullness.” The creation of the universe, Francis said, was not a singular event, but rather “went forward for centuries and centuries, millennia and millennia until it became what we know today.” “God is not... a magician, but the Creator who brought everything to life,” Francis said. “Evolution in nature is not inconsistent with the notion of creation, because evolution requires the creation of beings that evolve.”

Natural Selection Natural selection: the process by which individuals that are better adapted to their environment are more likely to survive and reproduce more than other individuals. Several factors affect this process.

Overproduction Most species produce too many offspring, and there are not enough resources for them all. The stronger species that get the resources will survive. Survival of the fittest

Variation Variation: any difference between individuals of the same species. Some organisms have certain traits that make them more likely to survive.

Competition Members of the same species living in the same area have to fight for the same resources.

Selection Organisms with more desirable traits will be chosen as mates by other organisms, and the desirable traits could be passed on.

Environmental Change A change in the environment could lead to certain species or members of a species having better chances of survival. Only traits that are inherited (genetically passed on) can be acted upon by natural selection.

Chapter 6: Change Over Time Lesson 2: Evidence of Evolution Cells and Heredity Chapter 6: Change Over Time Lesson 2: Evidence of Evolution

Evidential Support Fossils Fossils show differences between organisms from the past and organisms today. Show when/how new species evolved

Evidential Support Early Development Similarities early on suggest that organisms have the same ancestor.

Evidential Support Body Structure Similar body structures also suggest a common ancestor. Homologous structures: are similar structures in different species; could have different functions.

Evidential Support DNA and protein structure The more closely related the DNA is, the more closely related the organisms are. Usually DNA evidence supports the other types, or reinforces what scientists already believe to be true.

Chapter 6: Change Over Time Lesson 3: Rate of Change Cells and Heredity Chapter 6: Change Over Time Lesson 3: Rate of Change

Forming New Species Sometimes part of a species becomes isolated, or separated, from the rest of the species. When this happens, they can slowly, over a long time, evolve to have different traits that prevent reproduction.

Gradual Change Gradualism: small changes that add up to major changes over a long period of time.

Rapid Change Sometimes, a species remains unchanged for its existence. After extinction, a similar species appears that remains unchanged for a long period of time. This is called punctuated equilibrium.