Chapter 15: Darwin’s Theory of Evolution Biology- Kirby

15-1: The Puzzle of Life’s Diversity Evolution- change over time- process by which modern organisms have descended from ancient organisms. Theory- well-supported explanation of events that have occurred in nature. Charles Darwin developed the theory of evolution based on observations and evidence.

15-1: The Puzzle of Life’s Diversity Charles Darwin- –Interested in the diversity of life –Set sail on the Beagle and visited various places around the world to study organisms. –Galapagos Islands- noticed variations in organisms from different islands. –He wondered if these organisms were once part of the same species.

15-2: Ideas that shaped Darwin’s thinking Hutton and Lyell helped scientists realize that Earth was millions of years old and there are processes that make changes to things on Earth. Lamarck proposed that by selective use or disuse of organs, organisms gained or lost traits during their life. These traits would also be passed on to their offspring, and eventually a change in the species.

15-2: Ideas that shaped Darwin’s thinking Malthus thought that if the human population continued to grow unchecked, there would not be enough food or living space for everyone.

15-3: Darwin Presents his Case Darwin published his work in On the Origin of Species- –Individuals of a species vary from each other. –Artificial Selection- humans select the natural variations they want passed on. –Struggle for existence-members of each species compete to obtain food, living space, and other necessities.

15-3: Darwin Presents his Case –Fitness- the ability of an organism to survive and reproduce in its environment. –Adaptation- any inherited characteristic that increases an organism’s chance of survival. –Survival of the Fittest- individuals who survive and reproduce most successfully. –Natural Selection- nature’s selection for those individuals who are the fittest.

15-3: Darwin Presents his Case Evidence of Evolution- –Fossil record –Geographic distribution of living species –Homologous body structures –Similarities in early development

15-3: Darwin Presents his Case Strengths & Weaknesses of the Evolutionary Theory- –Darwin’s theory has been supported by many scientists; their research and discoveries often support Darwin’s theory. –However, there are still some questions about how a new species is created, how one becomes extinct, and how life began.