Honors Biology - Evolution (9th grade)

1. Species Are Fixed

• The belief that species do not change over time. This was the prevailing thought before Darwin’s theory of evolution.
  
  

2. Adaptations

• Traits that increase an organism's chances of survival and reproduction in a particular environment.
  
  

3. Allele Frequency

• The proportion of a particular allele among all allele copies in a population.
  
  

4. Analogous Structures

• Structures in different species that perform the same function but do not have a common evolutionary origin.
  
  

• Example: Wings of birds and insects.
  
  

5. Artificial Selection

• Humans intentionally breed organisms with desirable traits.
  
  

• Example: All dog breeds came from wolves through artificial selection.
  
  

6. Binomial Nomenclature

• A system for naming species using two names: the genus and species (specific epithet).
  
  

• Example: Homo sapiens (genus: Homo, species: sapiens).
  
  

7. Biogeography

• Study of the geographic distribution of species. It provides evidence for evolution by showing how 

species are adapted to their environments.

8. Bottleneck Effect

• A reduction in genetic diversity due to a drastic decrease in population size, often caused by a catastrophe.
  
  

9. Catastrophism

• The idea that Earth’s history has been shaped by sudden, short-lived, and violent events, such as natural disasters.
  
  

• Proposed by: Georges Cuvier.
  
  

10. Cladogram

• A diagram used to show the relationships among species based on shared traits.
  
  

11. Directional Selection

• Natural selection that favors one extreme phenotype over others.
  
  

• Example: Giraffes with longer necks are favored.
  
  

12. Disruptive Selection

• Natural selection that favors both extreme phenotypes and eliminates intermediate phenotypes.
  
  

• Example: Birds with either very small or very large beaks are favored.
  
  

13. Evolution

• A change in the genetic makeup of a population over time. Evolution occurs at the population level.
  
  

14. Fitness

• The ability of an organism to survive and reproduce. It is measured by how many offspring an individual leaves in the next generation.
  
  

15. Fossils

• Remains or traces of ancient organisms preserved in rocks. Fossils provide evidence of evolutionary changes over time.
  
  

16. Founder Effect

• A reduction in genetic variation when a small group of individuals starts a new population.
  
  

• Example: A few individuals from a large population colonize an isolated island.
  
  

17. Gene Flow

• The transfer of genetic material between populations through migration or interbreeding.
  
  

18. Gene Pool

• The total genetic diversity found within a population.
  
  

19. Genetic Drift

• A random change in allele frequencies in a small population, often due to chance events.
  
  

20. Genus

• A classification category that ranks above species and below family.
  
  

• Example: Homo (genus for humans).
  
  

21. Hardy-Weinberg Equilibrium

• A model used to measure genetic changes in a population over time. Five conditions for equilibrium:
  
  

  1. No mutations
     
     

  2. Random mating
     
     

  3. No natural selection
     
     

  4. Large population size
     
     

  5. No gene flow
     Formula: p² + 2pq + q² = 1
     
     

22. Heritability

• The proportion of variation in a trait that can be attributed to genetic differences.
  
  

23. Homologous Structures

• Structures that have a common evolutionary origin, even if they serve different functions.
  
  

• Example: The forelimbs of humans, bats, and whales.
  
  

24. Hybridization

• The process of breeding two different species to create hybrid offspring.
  
  

• Example: Mule (horse + donkey).
  
  

25. Inheritance of Acquired Characteristics

• Lamarck’s discredited idea that traits acquired during an organism’s lifetime can be passed on to offspring.
  
  

• Example: Lamarck suggested that giraffes’ long necks evolved because they stretched to reach higher leaves.
  
  

26. Interspecific Variation

• Variation between different species.
  
  

27. Intraspecific Variation

• Variation within the same species.
  
  

28. Microevolution

• Small-scale changes in allele frequencies in a population over time.
  
  

29. Migration

• Movement of individuals between populations, contributing to gene flow.
  
  

30. Mutation

• A change in the DNA sequence. Mutations can create new alleles and contribute to genetic variation.
  
  

31. Natural Selection

• The process by which individuals with beneficial traits are more likely to survive and reproduce. It is a key mechanism of evolution.
  
  

32. Normal Distribution

• A bell-shaped curve that represents the distribution of traits in a population. Most individuals have average traits, with fewer having extreme traits.
  
  

33. Paleontology

• The study of fossils and ancient life forms.
  
  

34. Phenotype

• The observable physical traits of an organism.
  
  

35. Population

• A group of individuals of the same species living in the same area.
  
  

36. Recombination

• The process during meiosis that shuffles genes and creates genetic variation.
  
  

37. Species

• A group of organisms that can interbreed and produce fertile offspring.
  
  

38. Specific Epithet

• The second part of a species name in binomial nomenclature, unique to each species within a genus.
  
  

39. Stabilizing Selection

• Natural selection that favors the average phenotype and reduces variation.
  
  

• Example: Human birth weight, where extremes are less common.
  
  

40. Uniformitarianism

• The idea that Earth’s features are shaped by continuous, uniform processes like erosion, proposed by James Hutton.
  
  

41. Variation

• Differences in traits among individuals in a population.
  
  

42. Vestigial Structures

• Structures that have lost their original function.
  
  

• Example: Human appendix or whale pelvic bones.
  
  

People and Their Contributions to Evolution

1. Carolus Linnaeus

• Developed binomial nomenclature and classified organisms.
  
  

2. Georges de Buffon

• Proposed that species change over time and may have common ancestors.
  
  

3. Erasmus Darwin

• Suggested that life evolved from a common ancestor.
  
  

4. Jean Baptiste Lamarck

• Proposed the idea of inheritance of acquired characteristics.
  
  

5. George Cuvier

• Advocated for catastrophism and believed that extinction had occurred.
  
  

6. James Hutton

• Proposed the idea of uniformitarianism, suggesting that geological processes occur gradually over time.
  
  

7. Charles Lyell

• Supported Hutton’s ideas and applied them to the understanding of Earth's geological history.
  
  

8. Thomas Malthus

• Proposed that populations grow exponentially, leading to competition for limited resources.
  
  

9. Alfred Russel Wallace

• Developed a theory of evolution by natural selection similar to Darwin’s.

Darwin’s Observations and Ideas

• Variation: Individuals in populations vary.
  
  

• Struggle for Existence: Organisms produce more offspring than can survive, leading to competition.
  
  

• Survival of the Fittest: Organisms with advantageous traits are more likely to survive and reproduce.
  
  

• Adaptation: Over time, favorable traits become more common in a population.
  
  

• Common Descent: All species are related by common ancestry.
  
  

Darwin’s Theory of Evolution by Natural Selection

• Mechanism: Natural selection works on heritable traits, acting on individuals.
  
  

• Inheritance: Traits passed from parents to offspring (genes).
  
  

• Variation: Variation exists due to mutations, recombination, and gene flow.
  
  

• Fitness: Those with advantageous traits survive and reproduce more, passing on their genes.
  
  

• Adaptations: Traits that increase survival and reproduction in a specific environment.