Objectives • Define the biological process of evolution • Summarize the history of scientific ideas about evolution • Describe Charles Darwin’s contributions to scientific thinking about evolution • Analyze the Darwin’s theory of evolution by natural selection • Relate the concepts of adaptation and fitness to the theory of natural selection Section 1 History of Evolutionary Thought

The Idea of Evolution • Evolution is the process of change in the inherited characteristics within populations over generations such that new types of organisms (species) develop from preexisting types Section 1 History of Evolutionary Thought

Evolutionary Relationships Between Whales and Hoofed Mammals Section 1 History of Evolutionary Thought

Early Biological Concepts of Evolution • Scientific understanding of evolution began to develop in the 17th and 18th centuries as geologists and naturalists compared geologic processes and living and fossil organisms around the world • Among geologists, Cuvier promoted the idea of catastrophism, and Lyell promoted uniformitarianism Section 1 History of Evolutionary Thought

Early Biological Concepts of Evolution • Among naturalists, Lamarck proposed the inheritance of acquired characteristics as a mechanism for evolution • An acquired trait was a physical change in an organism due to repeated use or practice (like a turtle’s neck reaching for leaves) • Lamarck’s idea has been proven false Section 1 History of Evolutionary Thought

Lamarck’s Idea…… an incorrect idea Section 1 History of Evolutionary Thought

Darwin’s Voyage • Charles Darwin was an Englishman who traveled around the world observing nature Section 1 History of Evolutionary Thought

Charles Darwin’s Ideas DescentwithModification • Darwin argued that descent with modification occurs through time, in other words, all species descended from common ancestors, and that naturalselection is the mechanism for evolution Section 1 History of Evolutionary Thought

Charles Darwin’s Ideas NaturalSelection was a theory proposed by Charles Darwin concerning descent of species with modification and possesses four parts • Overproduction – more individuals than environmental resources can support • GeneticVariation – individuals have different traits within a population • Competition – individuals compete for resources; those that are less fit die • DifferentialReproduction – survivors reproduce and pass traits on to offspring Section 1 History of Evolutionary Thought

Natural Selection Section 1 History of Evolutionary Thought

Adaptations • An adaptation is any favorable trait that increases the fitness of an organism • Fitness is a broadly defined term BUT for the theory of natural selection it has to do with reproduction • Increasing reproductivefitness increases the probability that the allele (associated with the adaptation) will be passed on to offspring Section 1 History of Evolutionary Thought

Adaptations Section 1 History of Evolutionary Thought

Objectives • Explain how fossils and rocks can be used to make inferences about evolutionary relationships • Explain how homologous structures and vestigal organs provide evidence of common ancestry • Explain how embryological development can be used to infer evolutionary relationships • Compare the use of biological molecules with other types of analysis of evolutionary relationships • Describe examples of evolution in action. Section 2 Evidence of Evolution

Evidence for Evolution • Evidence of evolution can be found by comparing several kinds of data, including the fossil record, biogeography, anatomy and development, and biological molecules • Evolutionary theories are supported when several kinds of evidence support similar conclusions Section 2 Evidence of Evolution

The Fossil Record • The age of fossils provides geologic evidence that supports theories about the age and development of Earth • Fossils are dated using radiometric analysis • The distribution of fossils the fossil record shows that the types and distribution of organisms on Earth have changed over time • “Older” fossils are deeper in the strata • More “recent” fossils are closer to the surface Section 2 Evidence of Evolution

The Fossil Record • The fossil record includes transitionalspecies or extinct organisms that were part of a developmental lineage giving rise to more modern groups • Transitional species show evidence of Darwin’s concept of descent with modification • In 1850 Darwin stated that fossils of terrestrial mammals with traits similar to aquatic mammals must exist • In the late 1980s they were discovered in Pakistan and Afganistan Section 2 Evidence of Evolution

Evidence of Whale Evolution Section 2 Evidence of Evolution

Evidence of Bird Evolution teeth and bill long feathered tail claws on wings long feathered legs Section 2 Evidence of Evolution

Biogeography • Biogeography, the study of the locations of organisms around the world, provides evidence of descent with modification Section 2 Evidence of Evolution

Plate Tectonics & Biogeography Section 2 Evidence of Evolution

Anatomy and Physiology • Homologousstructures have a common evolutionary origin • For example, a bird wing, human arm, whale flipper, or alligator leg all are derived from same tissues but have different functions • Homologous structures indicate a shared (or common) ancestry • Analogousstructures are similar in function but have different evolutionary origins • For example, the wings of birds, bats, and insects all have same function but are derived from very different tissues • Analogous structures donot accurately reflect ancestry Section 2 Evidence of Evolution

Forelimbs of Vertebrates Section 2 Evidence of Evolution

Anatomy and Physiology, continued • Vestigalstructures are those that exist but have no function • Many organisms with vestigial structures have shared (or common) ancestry with species possess a functional form of the structure • Examples include • the tail (bones) of humans • leg bones of whales and snakes Section 2 Evidence of Evolution

Vestigial Features Section 2 Evidence of Evolution

Anatomy and Physiology, continued • Embryologicaldevelopment(also known as ontogeny) can be used to infer evolutionary relationships Section 2 Evidence of Evolution

Evidence for Evolution: Biological Molecules • The level of similarity in the sub-unit sequences of molecules like RNA, DNA, and proteins reflects evolutionary history • Base-pair differences between organisms are due to the accumulation of spontaneous mutations • These mutations are passed from generation to generation and be used like a “molecular clock” • The more differences between molecular sequences of two organisms the longer ago they shared a common ancestor • Fewer differences indicate the organisms shared a more recent common ancestory Section 2 Evidence of Evolution

Hemoglobin Comparison Evidence for Evolution: Biological Molecules Section 2 Evidence of Evolution

Developing Theory • Modern science integrate Darwin’s theory with advances in biotechnology • Theories and hypotheses about evolution continue to be proposed and investigated • Evolution in action (i.e., actual observations of genotypic and phenotypic changes) are also accumulating, like • bacteria and antibiotic resistance • pesticide resistance in some insect pests • evolution of resistant HIV strains Section 2 Evidence of Evolution

Case Study: Caribbean Anole Lizards • DivergentEvolution • In divergent evolution, related populations become less similar as they respond to different environments • like between alpine and red foxes • Evolution by adaptiveradiation • Adaptive radiation is a form of divergent evolution in which a single group of organisms adapts to new environment • like anole lizards released on Caribbean islands Section 2 Evidence of Evolution

Natural Selection of Anole Lizard Species Section 2 Evidence of Evolution

Other Forms of Evolution • Artificialselection occurs when humans select and breed animals or plants for specific traits • Convergentevolution occurs when similar adaptations are selected for by the environment but do so at different places and times • Examples include wings or the streamlined shape of fish, sharks, whales, and sea lions • Sexualselection occurs when the opposite sex selects certain qualities or traits they deem “desirable” Section 2 Evidence of Evolution

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