Science - Evolution and Taxonomy

Taxonomy - How Organisms Are Sorted and How It Relates to Evolutionary Relationships

• Taxonomy is the classification of organisms based on shared characteristics and evolutionary history.

• Organisms are classified into a hierarchy: Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species (DKPCOFGS).

• Phylogenetics shows evolutionary relationships using a phylogenetic tree or cladogram, which groups organisms by common ancestry.

• More shared taxa = more closely related.

• Homologous structures, DNA similarities, and embryonic development help determine evolutionary relationships.

Types of Evidence for Evolution

1. Fossil Record – Shows gradual changes over time, transitional fossils link species.

2. Comparative Anatomy

   • Homologous structures – Same structure, different function (common ancestry).

   • Analogous structures – Same function, different structure (convergent evolution).

   • Vestigial structures – Leftover from ancestors, no longer useful (e.g., human tailbone).

3. Embryology – Similar embryonic development suggests a common ancestor.

4. Molecular Biology – DNA and protein similarities indicate relatedness.

5. Biogeography – Species distribution is influenced by continental drift and evolution.

6. Direct Observation – Evolution in action (e.g., antibiotic resistance, peppered moths).

Applying Continental Drift to Evolution

• Continental drift explains how species ended up where they are today.

• Pangaea (supercontinent) broke apart, isolating species, leading to speciation.

• Example: Marsupials in Australia evolved separately from placental mammals due to isolation.

Genetic Variation and Biodiversity Importance

• Genetic variation: Differences in DNA among individuals in a population.

• Sources of variation:

  • Mutations – Random changes in DNA.

  • Gene shuffling – Recombination during sexual reproduction.

• Importance of biodiversity:

  • Increases survival chances during environmental changes.

  • Prevents disease from wiping out an entire species.

  • Essential for ecosystem stability and food webs.

Connection Between Mutations, Adaptations, and Natural Selection

• Mutations create new traits.

• If beneficial, the trait becomes an adaptation (helps survival & reproduction).

• Natural selection favors individuals with helpful adaptations, increasing their frequency in a population.

• Example: A mutation causing thicker fur in a cold climate leads to better survival and reproduction.

Applying Natural Selection and Adaptations to Different Scenarios

• Industrial melanism (peppered moths): Dark-colored moths became more common after the Industrial Revolution due to soot-covered trees.

• Antibiotic resistance in bacteria: Bacteria with resistance genes survive and reproduce, spreading resistance.

• Darwin’s finches: Beak shapes evolved depending on available food sources.

• Camouflage in prey animals: Those that blend in avoid predators, leading to higher survival rates.

What Makes an Organism Successful?

• Reproductive success: Ability to pass on genes to the next generation.

• Survival skills: Ability to find food, avoid predators, and adapt to changes.

• Genetic fitness: Traits that improve survival and reproduction.

• Adaptability: Ability to adjust to new environments or changes.