Ch.15 Evolution

BIOS 112 Fundamentals of Organismal Biology Study Guide – Chapter 15

Learning Outcomes:

At the end of this lesson students will be able to . . .

1. Visualize processes as a sequential series of steps

   • Describe the process by which an adaptation evolves, as presented in section 15.2

     
     

     

   
   

Evaluate the strength of the supporting evidence

15.1 History of Evolutionary Thought

• Name the contribution that each of the following had on Darwin’s theory:

  • Carolus Linnaeus: Created a classification system for organisms, aiding in the understanding of biological diversity.

  • Georges Cuvier: Advocated for catastrophism, showing that extinctions occurred and supporting the idea of ancient life forms.

  • Jean-Baptiste de Lamarck: Proposed an early theory of evolution based on acquired characteristics; emphasized the idea that species change over time.

  • Charles Lyell: Introduced uniformitarianism, suggesting that the same geological processes have been shaping the earth over long periods, which supports an ancient earth view.

  • Thomas Malthus: Discussed population growth and resource limits, influencing Darwin's ideas on natural selection.

• What is the difference between catastrophism and uniformitarianism?

  • Catastrophism asserts that the Earth's geology and life have been shaped primarily by sudden and violent events (like floods and volcanic eruptions)

  • Uniformitarianism argues that the same processes observed today (like erosion and sedimentation) have been occurring in the same manner throughout Earth’s history.

15.2 Darwin’s Theory of Evolution

• How did Charles Darwin’s experience contribute to his theory of descent with modification?

  • His education: Received a diverse education in various sciences, laying the groundwork for his research.

  • HMS Beagle: His voyage on the Beagle allowed him to observe a wide variety of species and ecosystems.

  • Fossil observations: Noted similarities and differences between fossils and modern species, suggesting evolutionary change.

  • Biogeography: Studied species distribution and concluded that geographic isolation contributes to species diversity.

• What are Darwin’s four observations about Natural Selection?

  1. Organisms exhibit variation that can be passed from one generation to the next-that is, they have heritable variation

  2. Organisms compete for available resources

  3. Individuals within a population differ in terms of their reproductive success

  4. Organisms become adapted to conditions as the environment changes

     
     

• What evidence of selection is used to support Natural Selection?

  • Artificial selection: Human-directed breeding exhibiting rapid changes in species.

  • Galapagos finches (Grants): Observations showing rapid evolution of beak size in response to food availability.

  • Peppered moths: Color variation demonstrating natural selection during the Industrial Revolution.

  • Antibiotic resistance: Bacteria evolving to resist antibiotics, illustrating rapid selection.

15.3 Evidence for Evolution (Universal Common Descent)

1. Fossils

   • Fossil definition: Remains or traces of organisms from the past, typically preserved in rock.

   • Transitional fossils: Fossils that exhibit traits common to both an ancestral group and its derived descendant group.

   • Tiktaalik: A transitional fossil between fish and tetrapods, showcasing limb development.

   • Archaeopteryx: Intermediate between reptiles and birds, displaying both avian and dinosaur features.

   • Ambulocetus: A transitional form showing evolution from land mammals to whales.

   • Relative dating method: Determining the age of fossils based on their position in layers of rock.

   • Absolute dating method: Using radioactive decay to determine the specific age of fossils.

2. Biogeography

   • Marsupial history: Study of how marsupials are primarily found in Australia and the Americas, supporting evolution and dispersal patterns.

3. Anatomical Evidence

   • Homologous structures: Anatomical features that are similar due to shared ancestry.

   • Analogous structures: Features that serve similar functions but do not share a common evolutionary origin.

   • Vestigial structures: Body parts that have lost their original function through evolution (e.g., human appendix).

4. Biochemical (Molecular) Evidence

   • DNA & RNA homology: Similarities in genetic material across species indicating common ancestry.

   • Protein homology: Similarities in protein structures among different organisms.

5. Developmental Evidence

   • Hox genes: Genes that control the body plan of an embryo along the head-tail axis, indicating common ancestry.

   • Embryology: Study of embryonic development, revealing similarities among embryos of different species.

Criticisms of Evolution – “misconceptions” listed:

1. Misunderstanding of transitional fossils and their implications.

2. Suggestions that evolution is a linear process rather than a branching tree.

3. The assumption that all traits must be advantageous, ignoring neutral evolution.

4. Perception that evolution is just a theory lacking substantial evidence.