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Lecture on Evolution and Natural Selection
Jul 30, 2024
Lecture on Evolution and Natural Selection
Key Topics Covered
Special Creation Thinking vs. Population Thinking
Definition of Evolution
Natural Selection as an Evolutionary Mechanism
Theories and Contributions by Key Figures
Evidence Supporting Evolution
Special Creation Thinking vs. Population Thinking
Special Creation Thinking
Beliefs: Ancient Perspective
Species do not change.
Species are not related.
Life on Earth is young (~6,000 years old).
Population Thinking
Beliefs: Modern Perspective
Species do change.
Species are related.
Life on Earth is old (billions of years).
Definition of Evolution
Key Definition (Exam Note):
Change in allele frequencies in a population over time.
Natural Selection as an Evolutionary Mechanism
One of four evolutionary mechanisms (others not covered in this lecture).
Proposed by Charles Darwin and Alfred Russel Wallace.
Explains how populations adapt to their environments.
Important Concept (Exam Note):
Populations evolve, not individuals.
Contributions by Key Figures
Charles Darwin
Published
On the Origin of Species by Means of Natural Selection
(1859).
Proposed that evolution by natural selection could explain well-adapted populations.
Alfred Russel Wallace
Co-formulated the theory of natural selection along with Darwin.
Plato
Greek philosopher.
Believed species do not change (typological thinking).
Aristotle
Developed the Great Chain of Being (Hierarchy of Species).
Believed species do not change but were hierarchically ranked.
Jean-Baptiste Lamarck
First to propose that species change over time.
Incorrectly believed in evolution as a progressive change up a hierarchy.
Evidence Supporting Evolution
Fossil Record
Fossils show that species have changed over time.
Relative Age of Fossils:
Deeper fossils are older.
Absolute Age of Fossils:
Can be measured using radioactive decay.
Transitional Features
Traits intermediate between ancestral and derived species.
Vestigial Traits
Structures that are fully functional in one species but poorly developed in another.
Examples: Tiny hip and leg bones in whales and snakes, reduced wings in flightless birds, eye sockets in blind fish.
Homologies
Genetic Homology
Similarities in DNA, RNA, or amino acid sequences.
Developmental Homology
Similarities in embryo stages.
Structural Homology
Similarities in adult morphology.
Case Study: Cetaceans
Internal Consistency:
Multiple data sources support the same conclusion of shared ancestry.
Closest living relatives to whales: Hippos.
Evidence: Fossil record, DNA sequences, vestigial bones.
Summary
Key Concepts for Exam:
Special Creation Thinking vs. Population Thinking.
Definition of Evolution.
Natural Selection.
Contributions from key figures.
Evidence supporting evolutionary theory.
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