CH 15 Darwin’s Theory of Evolution 15-1 The Puzzle of Life’s Diversity 15-2 Ideas that Shaped Darwin’s Thinking 15-3 Darwin presents his Case 15-1 The Puzzle of Life’s Diversity 15-2 Ideas that Shaped Darwin’s Thinking 15-3 Darwin presents his Case

15-1 The Puzzle of Life’s Diversity  Evolution, or change over time, is the process by which modern organisms have descended from ancient organisms  A scientific theory is a well-supported testable explanation of phenomena that have occurred in the natural world  Evolution, or change over time, is the process by which modern organisms have descended from ancient organisms  A scientific theory is a well-supported testable explanation of phenomena that have occurred in the natural world

15-1 The Puzzle of Life’s Diversity  During his travels, Darwin made numerous observations and collected evidence that led him to propose a revolutionary hypothesis about the way life changed over time

15-1 The Puzzle of Life’s Diversity  Darwin saw patterns in evolution not only in living organisms but also in comparing their ancestors fossils or preserved remains  Darwin observed that the characteristics of many animals and plants varied noticeably among the different Galapagos Islands  Darwin saw patterns in evolution not only in living organisms but also in comparing their ancestors fossils or preserved remains  Darwin observed that the characteristics of many animals and plants varied noticeably among the different Galapagos Islands

15-1 The Puzzle of Life’s Diversity  Pg 372 (1-5) Don’t Fall Behind

15-2 Ideas that Shaped Darwin’s Thinking  Most Europeans believed Earth and life had been created a thousand years ago  Before setting sail on the Beagle, Darwin studied the rich fossil record and started changing his beliefs about life’s creation  Most Europeans believed Earth and life had been created a thousand years ago  Before setting sail on the Beagle, Darwin studied the rich fossil record and started changing his beliefs about life’s creation

15-2 Ideas that Shaped Darwin’s Thinking  Before Darwin’s voyage, James Hutton and Charles Lyell showed the Earth to be millions not thousands of years old due to geologic record  This led Darwin to having 2 ideas  If the Earth can change, so can life  This change would have taken a very long time  Before Darwin’s voyage, James Hutton and Charles Lyell showed the Earth to be millions not thousands of years old due to geologic record  This led Darwin to having 2 ideas  If the Earth can change, so can life  This change would have taken a very long time

15-2 Ideas that Shaped Darwin’s Thinking  Lamarck proposed that by selective use or disuse or organs, organisms acquired or lost certain traits during their lifetime  These traits could be passed on to their offspring, overtime leading to changes in species  Lamarck proposed that by selective use or disuse or organs, organisms acquired or lost certain traits during their lifetime  These traits could be passed on to their offspring, overtime leading to changes in species

15-2 Ideas that Shaped Darwin’s Thinking  Lamarcks ideas  Animals are always changing to become more complex and closer to perfection  Animals will gain or lose organs by using their bodies in specific ways (arm  wing)  Inheritance of acquired traits  lift weights and get strong you will have strong kids  Even though he was wrong about most of his ideas, they led to better theories  Lamarcks ideas  Animals are always changing to become more complex and closer to perfection  Animals will gain or lose organs by using their bodies in specific ways (arm  wing)  Inheritance of acquired traits  lift weights and get strong you will have strong kids  Even though he was wrong about most of his ideas, they led to better theories

15-2 Ideas that Shaped Darwin’s Thinking  Last influence on Darwin-Thomas Malthus  Malthus reasoned that if the human population continued to grow unchecked, sooner or later there would be insufficient living space and food for everyone  Humans have a couple kids, trees can have millions  why is the Earth not completely covered in trees? Why…..  Last influence on Darwin-Thomas Malthus  Malthus reasoned that if the human population continued to grow unchecked, sooner or later there would be insufficient living space and food for everyone  Humans have a couple kids, trees can have millions  why is the Earth not completely covered in trees? Why…..

15-2 Ideas that Shaped Darwin’s Thinking  Pg 377- (1-5)

15-3 Darwin presents his Case  Darwin returned to England-1836  Darwin released “On the Origin of Species” in 1859  In Artificial Selection nature provided the variation, and humans selected those variations that they found useful  Darwin returned to England-1836  Darwin released “On the Origin of Species” in 1859  In Artificial Selection nature provided the variation, and humans selected those variations that they found useful

15-3 Darwin presents his Case  The Struggle for existence means that members of each species compete regularly to obtain food, living space, and other necessity of life  Darwin called the ability of an individual to survive and reproduce in its specific environment Fitness  The Struggle for existence means that members of each species compete regularly to obtain food, living space, and other necessity of life  Darwin called the ability of an individual to survive and reproduce in its specific environment Fitness

15-3 Darwin presents his Case  Fitness results from Adaptations or any inherited characteristics that increases an organism’s chance of survival  Best suited animals have a higher survival rate in the process- Survival of the Fittest  Over time, Natural Selection results in changes in the inherited characteristics of a population  These changes increase a species fitness  Fitness results from Adaptations or any inherited characteristics that increases an organism’s chance of survival  Best suited animals have a higher survival rate in the process- Survival of the Fittest  Over time, Natural Selection results in changes in the inherited characteristics of a population  These changes increase a species fitness

15-3 Darwin presents his Case  The principle that all living and extinct animals have one common ancestor is known as Common Descent  Evidence that animals have been evolving for millions of years on Earth are the fossil record, geographic distribution of animals, homologous structures, and similarities in early development  The principle that all living and extinct animals have one common ancestor is known as Common Descent  Evidence that animals have been evolving for millions of years on Earth are the fossil record, geographic distribution of animals, homologous structures, and similarities in early development

15-3 Darwin presents his Case  Structures that have different mature forms but develop from the same embryonic tissue are called Homologous structures

15-3 Darwin presents his Case  The organs of many animals are so reduced in size that they are just traces of homologous organs in other species are called Vestigial Organs  Pg  386  (1-4)  The organs of many animals are so reduced in size that they are just traces of homologous organs in other species are called Vestigial Organs  Pg  386  (1-4)