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Evolution

Evolution. 15. The Big Idea. The theory of natural selection explains evolution and the diversity of life. Main Idea #1. Charles Darwin developed a theory of evolution based on natural selection. The 1st Scientific Hypothesis of Evolution.

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Evolution

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  1. Evolution 15

  2. The Big Idea The theory of natural selection explains evolution and the diversity of life.

  3. Main Idea #1 • Charles Darwin developed a theory of evolution based on natural selection.

  4. The 1st Scientific Hypothesis of Evolution • French biologist Jean Baptiste de Lamarck offered the first complete explanation of evolution in 1809. • He was the first to argue that fossils were the remains of extinct animals. • His concept was transformational, meaning individuals transform their own traits in order to evolve.

  5. Uniformitarianism • Geologist Sir Charles Lyell - the principle of uniformitarianism. • Two parts: • laws of physics and chemistry remain the same throughout earth’s history • past geological events occurred by natural processes similar to those that observed today • He said Earth’s age must be measured in millions of years.

  6. Charles Robert Darwin1809-1882 • In 1831, Darwin sailed aboard the very small ship the HMS Beagle. • During his 5-year voyage, he collected a wide variety of flora and fauna from South America and surrounding islands. • He found long extinct fossils, including seashells in the Andes Mountains at an altitude of 13,000 feet. • He also witnessed earthquakes and severe erosion that helped to confirm his ideas about geology.

  7. Darwin & The Galapagos Islands • These volcanic islands are on the equator, 600 miles west of Ecuador. • Each island varied in tortoises, iguanas, mockingbirds, and ground finches. • The islands had similar climate, but varied greatly in vegetation. • Darwin inferred that island species originated in South America, and were modified over many years under the varying conditions of different islands.

  8. Darwin (continued...) • Darwin conducted the remainder of his work at home in England, where all of his notebooks had been sent home ahead of him in October 1836. • His travel journal, The Voyage of the Beagle, was published three years later, but he continued his research on the evolution of species by natural selection. • Darwin first presented his ideas in a paper in 1844, but did not began writing the larger volume until 1856. By 1858, he had received a manuscript from Alfred Russel Wallace summarizing his ideas on natural selection. • Geologist Lyell was instrumental in convincing Darwin to publish a joint paper with Wallace. • Darwin’s book On the Origin of Species by Means of Natural Selection was published in 1859. All printed copies sold out in one day.

  9. Darwin’s Theory of Evolution • Darwin’s work actually included 5 separate theories • Perpetual Change is the basic theory of evolution on which the others are based stating that the world is constantly changing. • Common Descent (controversial theory) states that all forms of life descended from a common ancestor. • Multiplication of Species - species divide and split into different species, which can no longer interbreed • Gradualism - large differences actually originate from an accumulation of many smaller differences • Natural Selection - explains the selective processes of the environment, through a phenomenon called adaptation.

  10. Natural Selection & Speciation

  11. Natural Selection • The Ideas Behind Natural Selection • Individuals in a population show variations. • Variations can be inherited. • Organisms have more offspring than can survive on available resources. • Variations that increase reproductive success will have a greater chance of being passed on.

  12. Types of Evidence of Evolution • Fossil Record • Comparative Anatomy • Homologous Structures - similar structures inherited from a common ancestor • Vestigial Structures - structures that are reduced forms of functional structures in other organisms; get smaller over generations • Analogous Structures - structures that have similar function, but not similar shapes; not inherited from a common ancestor

  13. Evidence (continued...) • Comparative Embryology - many embryos share characteristics that are not alike in the adult form • Comparative Biochemistry - the more closely related two species are, the more amino acid sequences they will share • Geographic Distribution - evolution may be closely linked to climate and geographical characteristics

  14. Speciation • Speciation is the evolutionary process by which new biological species arise. • Allopatric speciation - a physical barrier divides one population into one or more populations • mountain ranges, lava flows, channels between islands, wide rivers • believed to be the most common type of speciation • Sympatric speciation - no physical barrier separates the populations • the ancestor species and new species live side by side

  15. Types of Evolution • Chemical Evolution - formation of organic molecules from inorganic substances • primordial soup; chemicals in the early ocean giving rise to organic, and eventually, living matter • Organic Evolution - changing of a species into something different by the accumulation of small changes over time

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