Lecture Notes: Introduction to Biological Evolution
Key Concepts of Biological Evolution
Microevolution
- Definition: Evolutionary changes occurring within a species; ongoing process.
- Example: Evolution occurring in bacteria within the human gut.
- Significance: Important for understanding contemporary evolutionary processes.
Macroevolution
- Definition: Large-scale evolutionary changes that result in the formation of new species and broader taxonomic groups.
- Historical Impact: Constraints on current evolutionary processes due to past events.
- Time Scale: Evolutionary processes over 3.8 billion years.
Structure of Course
- Lectures on Microevolution: 6 lectures focusing on foundational principles.
- Lectures on Reproductive Success: 5 lectures covering sexual selection, mate choice.
- Macroevolutionary Principles: Focus on speciation and analyzing the tree of life.
- Integration of Micro and Macroevolution: Coevolution and evolutionary medicine.
Historical Context of Evolutionary Thought
Pre-19th Century Views
- Age of the Earth: Believed to be thousands of years old.
- Species Creation: Fixed, unchanging since creation.
- Extinction: Initially believed not to occur.
- Adaptation: Attributed to divine intervention.
Influence of Enlightenment
- Alexander von Humboldt: Explored theories of extinct species.
- Charles Lyell: Concept of 'deep time', influenced Darwin.
Darwin's Contributions
- Natural Selection: Core mechanism of evolutionary change.
- Influence of Malthus: Ideas on population growth and competition.
- Voyages on HMS Beagle: Observations in South America and Galapagos Islands.
Development of Evolutionary Theory
- Darwin and Wallace: Jointly published initial theories on natural selection.
- The Origin of Species: Published by Darwin, pivotal book in evolutionary biology.
Principles of Natural Selection
Preconditions for Natural Selection
- Variation in Reproductive Success: Different reproductive rates among individuals.
- Variation in Traits: Observable differences in traits like height.
- Heritability: Degree to which traits are passed down generations.
- Correlation Between Traits and Reproductive Success: Necessary for natural selection.
Outcomes of Natural Selection
- Adaptation: Traits better suited for survival increase in frequency.
- Random Drift: Results when no correlation exists between traits and reproductive success.
Macroevolution and the Tree of Life
Key Concepts
- One Tree of Life: All life forms share a common origin.
- Speciation Events: Branch points in the evolutionary timeline.
- Major Historical Events: Mass extinctions, meteorite impacts, and shifts in life's organizational structure.
Evolutionary Timeline
- Life originated approximately 3.6 to 3.9 billion years ago.
- Eukaryotic Evolution: Emergence of organized cell structures and multicellularity.
- Permian Mass Extinction: Significant historical extinction event.
- Cultural Evolution: Impact of language and writing on human evolution.
Examination of Biological Disciplines
- Microbiology & Biochemistry: Study of life processes common across all lifeforms.
- Genetics & Cell Biology: Focus on eukaryotic development and genetic processes.
- Developmental Biology: Emergence of multicellular organisms.
- Neurobiology and Anthropology: Study of recent evolutionary developments.
Conclusion and Reflection
- Interconnection with Non-Life: Evolutionary connection from living organisms to abiotic matter.
- Significance of Evolutionary Biology: Offers a comprehensive view of life's continuity on a cosmic scale.
Next Lecture Topic: Basic Genetics