RC

AUBIO 112 Lecture 2

Evolution & Scientific Method

  • Week 1 - Lecture 2: AUBIO 112 - Evolution and Biodiversity, Winter 2025, Bjorn Lie

Learning Objectives

  1. Define evolution

  2. Understand differences between theory and hypothesis

  3. Consider application of the scientific method to study evolution

Defining Evolution

General Definition

  • Gradual development from simple to complex forms (Oxford English Dictionary).

Biological Definition

  • Inherited Change: The genetic transformation within lineages.

  • Reproduction: Gene and trait inheritance from parents to offspring.

  • Change: Offspring are combinations of traits, not exact copies.

  • Lineage: Continuity of genetic inheritance across generations.

Evolutionary Change

  • Reproductive Success: More successful parents have more offspring.

  • Genetic Variation: Introduced by random mutations, crucial for evolution.

  • Variation: Differences among individuals in a population (e.g., red-fronted lemurs).

Is All Change Evolution?

  • Not all changes signify evolution.

Reasons Growth & Metamorphosis Aren't Evolution

  1. Does not imply improvement.

  2. Non-linear progression; evolution best represented as a tree.

  3. "More evolved" does not equate to being better.

Brief History of Evolution

Key Figures

  • Charles Darwin (1809 - 1882): Joined HMS Beagle (1832) and published "On the Origin of Species" (1859).

  • Georges-Louis Leclerc (1707): Proposed common ancestry among apes.

  • Jean-Baptiste de Lamarck: Suggested traits acquired in a lifetime can be inherited.

Darwinism & Natural Selection

  • Darwinism: Advocates natural selection—adapted organisms survive better.

  • Evolution as Theory: Distinct from belief; is a scientific theory.

Understanding Theories and Hypotheses

Hypotheses

  • Proposed explanations arising from observations and questions; starting points for investigations.

The Scientific Method Steps

  1. Observations: Noticing patterns or phenomena.

  2. Questions: Formalized research questions based on observations.

  3. Hypotheses: Plausible answers to questions.

  4. Predictions: Specific predictions based on hypotheses.

  5. Studies: Design studies to collect data against predictions.

  6. Iteration: Process is recursive; refine hypotheses based on data.

Case Study: Tuskless Elephants

  • Observation: 50% of females over 20 in Gorongosa National Park are tuskless.

  • Broad Question: Why so many tuskless elephants?

  • Specific Question: Did poaching influence tusklessness?

  • Hypotheses: Answers could be "NO" or "YES.

Predictions

  1. If tusklessness results from poaching, expect more tuskless births post-war.

  2. If not from selection, expect similar numbers of tuskless and tusked elephants post-war.

Findings

  • Research indicates human interference, notably ivory poaching, has led to evolution of tuskless elephants.

Next Class Expectation

  • Evidence for evolution.