Introduction

• The class is conducted via Zoom due to likely circumstances.

• The instructor encourages students to enjoy the weather outside and notes its rarity.

General Announcements

• Office Hours:

  • Available today on Zoom, with a request to notify the instructor upon arrival.

  • Students should include their first and last names on all assignments.

• Meetings and Deadlines:

  • A biology zoology meeting is scheduled for Wednesday at 12:40 in Science 360.

  • Due dates include:

  • First lab report due Friday

  • A quiz on Friday

• Thought Questions:

  • A review of the previous session’s thought question is planned.

  • The possibility of addressing a new thought question today.

Lecture Coverage and Structure

• Today's session will be structured as a lecture with planned catch-up on course material.

• Hardy Weinberg Principle:

  • The aim is to cover this concept, noted as more effectively taught in person with a chalkboard.

• Presentation order may differ from previous year’s slides.

Evolutionary Theory and Darwin

• Charles Darwin's Contributions:

  • Discussion of Darwin’s theory of evolution and its deviation from predecessors like Lamarck.

  • Key observations:

  • Evolution operates at the population level—not the individual level.

  • Definition of Population:

    • A group of individuals of the same species living in a specific area at the same time.

  • Explanation of Species Concept:

  • Complexity surrounding species definition; implications for gene flow and evolution.

  • Definition of Evolution:

  • Evolution is defined as the change in gene frequency in a population over time.

  • Emphasis on the fact that individuals do not evolve; rather, populations evolve.

Observations of Evolution

• Observed Examples:

  • Pesticide Resistance:

  • Example of beetles becoming resistant to pesticides; discussions on heritable traits.

  • Differential survivorship based on genetic traits among individuals within a population.

  • Antibiotic Resistance:

  • Increases in antibiotic resistance in bacteria, notably Staphylococcus aureus.

    • Discussion on the timeline of resistance emergence in hospitals.

  • Galapagos Finches Study:

  • Research conducted by the Grants studying evolution in response to environmental changes, specifically regarding finch beak size during droughts.

  • Observations made visit years indicate beak adaptation to food availability, showcasing rapid evolutionary change.

Microevolution vs. Macroevolution

• Microevolution:

  • Examples include changes in gene frequencies over short timescales (e.g., resistance).

• Macroevolution:

  • Refers to broader evolutionary changes observed over longer periods and fossil records.

  • Definition of complex traits and the importance of incremental steps in evolution.

• Discusses the evolution of birds from dinosaurs, linking features such as feathers with warmth and potential for gliding/flight.

The Role of Transitional Fossils

• Transitional Fossils:

  • Essential evidence of evolutionary processes with examples like the fish-tetrapod transition (Tiktaalik).

  • The horse lineage is referenced as another classic example, illustrating changes in size, toe structure, and dietary adaptations.

• Cetaceans:

  • Evolution of whales from terrestrial ancestors; genetic lineages support relationships among modern species.

Vestigial Structures

• Definition of Vestigial Structures:

  • Structures diminishing in original function due to evolutionary change (e.g., human tailbone, whale pelvis).

• Discusses examples that retain minor functions but primarily serve as evolutionary remnants.

Biogeography and Adaptive Radiation

• Definition of Biogeography:

  • Study of geographic distribution of species in relation to their evolutionary history.

• Alfred Russel Wallace and Wallace's Line:

  • Significant contributions to the understanding of species distribution and characteristics across geographic lines.

Homologous and Analogous Structures

• Homologous Structures:

  • Shared due to common ancestry; enables study of evolutionary relationships and classification.

• Analogous Structures:

  • Exhibiting similarities not due to shared ancestry; lead to possible confusion in interpretation.

• Cases of homologous structures examined through arms of tetrapods and their adaptations (e.g., humans, birds, bats).

• Use of genetic data to analyze and form evolutionary trees.

Developmental Biology and Evolutionary Patterns

• Discussion on developmental biology's role in understanding evolutionary relationships, referencing the concept of ontogeny recapitulating phylogeny.

• The importance of early vs. late developmental changes in species evolution.

Conclusion and Next Session

• Encouragement for students to enjoy the weather and participate in office hours afterward.

• Planned discussion on the evolution of powered flight in the next session, setting the stage for further exploration of evolutionary biology concepts.