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Chapter 22 Descent with Modification: A Darwinian View of Life Chapter 22 Descent with Modification: A Darwinian View of Life Hutton and Lyell were geologists in the 1700’s Chapter 22 Descent with Modification: A Darwinian View of Life Hutton and Lyell were geologists in the 1700’s. Geologic gradualism: Profound change can be the cumulative product of slow but continuous processes. Chapter 22 Descent with Modification: A Darwinian View of Life Lamarck published a theory of evolution in 1809, the year that Darwin was born Chapter 22 Descent with Modification: A Darwinian View of Life Lamarck published a theory of evolution in 1809, the year that Darwin was born. The fossil record shows lines of descent Chapter 22 Descent with Modification: A Darwinian View of Life Lamarck published a theory of evolution in 1809, the year that Darwin was born. The fossil record shows lines of descent. Species adapt to their environment. Inheritance of acquired characteristics. Chapter 22 Descent with Modification: A Darwinian View of Life Darwin did field research Chapter 22 Descent with Modification: A Darwinian View of Life Darwin did field research. At age 22, he signed onto the HMS Beagle Chapter 22 Descent with Modification: A Darwinian View of Life Darwin did field research. At age 22, he signed onto the HMS Beagle. In the Galapagos islands, he collected many specimens Chapter 22 Descent with Modification: A Darwinian View of Life Darwin did field research. At age 22, he signed onto the HMS Beagle. In the Galapagos islands, he collected many specimens. He published his conclusions only reluctantly, and decades later. Chapter 22 Descent with Modification: A Darwinian View of Life Observation # 1: All species have such great potential fertility that their would increase exponentially if all their offspring survived to reproduce. Chapter 22 Descent with Modification: A Darwinian View of Life Observation # 2: Populations actually tend to remain stable. Chapter 22 Descent with Modification: A Darwinian View of Life Observation # 3: Environmental resources are limited. Chapter 22 Descent with Modification: A Darwinian View of Life Inference # 2: There is a struggle for existence. Chapter 22 Descent with Modification: A Darwinian View of Life Observation # 4: No two individuals are alike. Individuals in a population vary extensively in their characteristics. Chapter 22 Descent with Modification: A Darwinian View of Life Observation # 5: Much of this variation is inherited. Chapter 22 Descent with Modification: A Darwinian View of Life Inference # 2: Those individuals whose characteristics best fit their environment are the ones that best survive to ass on their characteristics. Chapter 22 Descent with Modification: A Darwinian View of Life Inference # 3: The population gradually changes over time, with favorable characteristics becoming more common. Chapter 22 Descent with Modification: A Darwinian View of Life Some subtle points: Chapter 22 Descent with Modification: A Darwinian View of Life Some subtle points: •Individuals do not evolve; only populations evolve Chapter 22 Descent with Modification: A Darwinian View of Life Some subtle points: •Individuals do not evolve; only populations evolve. •Natural selection can only act on heritable variations Chapter 22 Descent with Modification: A Darwinian View of Life Some subtle points: •Individuals do not evolve; only populations evolve. •Natural selection can only act on heritable variations. •The same traits that are favorable in one time and place may be detrimental in others. Chapter 22 Descent with Modification: A Darwinian View of Life Adaptive evolution is an observable phenomenon in the world today Chapter 22 Descent with Modification: A Darwinian View of Life Adaptive evolution is an observable phenomenon in the world today. •Insecticide resistant insects Chapter 22 Descent with Modification: A Darwinian View of Life Adaptive evolution is an observable phenomenon in the world today. •Insecticide resistant insects. •Drug resistant HIV. Chapter 22 Descent with Modification: A Darwinian View of Life Other evidence: Chapter 22 Descent with Modification: A Darwinian View of Life Other evidence: Homologies Chapter 22 Descent with Modification: A Darwinian View of Life Other evidence: Homologies •Anatomical Chapter 22 Descent with Modification: A Darwinian View of Life Other evidence: Homologies •Anatomical •Vestigial Chapter 22 Descent with Modification: A Darwinian View of Life Other evidence: Homologies •Anatomical •Vestigial •Embrylogical Chapter 22 Descent with Modification: A Darwinian View of Life Other evidence: Homologies •Anatomical •Vestigial •Embrylogical •Molecular. Chapter 22 Descent with Modification: A Darwinian View of Life Other evidence: Chapter 22 Descent with Modification: A Darwinian View of Life Other evidence: •Biogeography Chapter 22 Descent with Modification: A Darwinian View of Life Other evidence: •Biogeography •Fossil record. Chapter 22 Descent with Modification: A Darwinian View of Life Just a theory? Chapter 22 Descent with Modification: A Darwinian View of Life Just a theory? “A theory…does not become widely accepted in science unless its predictions stand up to thorough and continual testing by experiments and observation. … Even then, good scientists do not allow theory to become dogma.” (pg 442)