Microevolution and Speciation

Overview of the Test

• Test will cover materials listed in the homework log.
• Only covering slides 48 to 58 today.

Understanding Microevolution

• Microevolution vs. Macroevolution:
  • Microevolution: Small scale changes affecting allele frequency within a population (e.g., traits in closely related species).
  • Macroevolution: Large scale changes leading to speciation over long periods (e.g., evolution of different species).

Importance of Note-Taking Skills

• Problem-solving and note-taking skills are essential for all careers.
• Key strategies for effective note-taking:
  • Condense information by omitting unnecessary words.
  • Avoid rewriting previously learned definitions when taking notes.
  • Focus on concise ideas that can be expanded when studying.

Factors Affecting Microevolution

• Genetic Drift: Changes in allele frequencies due to random events.
  • Founder Effect: A small group starts a new population, limiting genetic variation (e.g., the Amish community).
  • Bottleneck Effect: A significant reduction in population size reduces genetic variability (e.g., northern elephant seals).
• Gene Flow: Movement of alleles between populations due to migration, which changes allele frequencies.

Types of Isolation Leading to Speciation

• Geographic Isolation: Physical barriers separate populations, leading to divergence (e.g., a river or mountain).
• Reproductive Isolation: Differences in mating rituals or anatomy prevent successful mating.
• Temporal Isolation: Species breed at different times (e.g., flowers blooming in different seasons).

Speciation Types

• Allopatric Speciation: Speciation due to a physical barrier separating populations (e.g., squirrels separated by the Grand Canyon).
• Sympatric Speciation: Speciation without physical barriers, often due to behavioral differences or ecological factors (e.g., variations in tree species within the same area).

Patterns of Evolution

• Divergent Evolution: Species evolve from a common ancestor but develop different traits due to environmental pressures (e.g., different species of insects).
• Coevolution: Evolution of one species drives the evolution of another (e.g., hummingbirds and trumpet flowers).
• Convergent Evolution: Different ancestors evolve similar traits due to similar environmental pressures (e.g., sharks and dolphins).

Evolutionary Processes

• Gradualism: Evolution occurs through gradual changes over long periods.
• Punctuated Equilibrium: Evolution is marked by significant changes occurring rapidly after long periods of stability.
• Adaptive Radiation: Rapid evolution of diversely adapted species from a common ancestor when resources are plentiful (e.g., Galapagos finches with different beak shapes).

Review and Resources

• Review materials available on Schoology for additional practice, including notes on structures, speciation, natural vs artificial selection, and selection types (disruptive, stabilizing, directional).
• Focus on key concepts and practice areas to prepare for the SOL review.