Study Guide Chapter 16: Life on Earth Evolution

Timeline Methods: Scientists use relative chronologies (comparing fossil layers) and absolute chronologies (radiometric dating).
Radiometric Dating: This process uses the ratio of radioactive isotopes to stable daughter elements to determine the age of rocks based on known decay rates.
Radioactive Isotope: An unstable element form that decays by emitting high-energy particles until it reaches a stable form.
Half-Life: The duration required for 50% of a radioactive isotope in a sample to decay.
Rock Types: - Sedimentary Rocks: Formed by the compression of eroded particles. - Igneous Rock: Formed by the cooling of molten lava; contains zircon crystals used for dating.
Geological History: Life on Earth spans approximately $3.5$ billion years. Multiple independent radiometric techniques are used to confirm ages across this timeline.

Biogeography: The study of the geographical distribution of organisms.
Plate Tectonics: The movement of the Earth's upper mantle and crust that causes Continental Drift.
Large-Scale Patterns: Ancient landmasses like Pangaea and Gondwana explain current species distributions. - Polar Bears vs. Penguins: Polar bear ancestors were North and penguin ancestors were South when Pangaea split; they remain isolated by distance and warm climates. - Ratites: Flightless birds (Rheas, Ostriches, Emus) are found in South America, Africa, and Australia because these continents were once in close proximity. - Fire-bellied toads: Found in Europe and China because they were once part of the single continent Eurasia.

Extinction: The total elimination of all individuals in a species.
Mass Extinction: A rapid event resulting in the loss of $50\%$ \text{ to } $90\%$ of all living species.
Adaptive Radiation: The spreading and diversification of organisms when they colonize new, empty habitats. - Example: Marsupials in Australia diversified after the extinction of dinosaurs because they faced no competition from placental mammals after Australia broke away from South America and Africa.

Taxonomy: The identification, naming, and classification of organisms based on shared traits.
Classification Hierarchy (Least to Most Diverse): Species $\rightarrow$ Genus $\rightarrow$ Family $\rightarrow$ Order $\rightarrow$ Class $\rightarrow$ Phylum $\rightarrow$ Kingdom $\rightarrow$ Domain.
Three Domains of Life: 1. Bacteria: Single-celled, no nucleus. 2. Archaea: Single-celled, no nucleus, found in extreme environments. 3. Eukarya: Single-celled or multicellular organisms with nuclei.
Convergent Evolution: Process where distantly related species evolve similar adaptations due to similar environmental constraints (e.g., gliding mammals like flying squirrels and sugar gliders).
Phylogeny: The evolutionary history represented by a Phylogenetic Tree. Nodes on these trees represent the last common ancestor of the organisms above that point.

Q: How old is a rock layer containing zircon crystals with $60\%$ Uranium-238 and $40\%$ Lead-206?
A: Approximately $3.75$ billion years old.
Q: What are the proportions of elements in a $2$ -billion-year-old igneous rock?
A: Approximately $70\%$ Uranium-238 and $30\%$ Lead-206.
Q: What is the correct order of organisms from earliest appearance to latest?
A: 1. Soft-bodied invertebrates, 2. coral species, 3. fungi, 4. seedless plants, 5. insects, 6. reptiles, 7. mammals, 8. flowering plants, 9. cone-bearing plants, 10. grasses.
Q: Which two species among the Vampire Bat, King Cobra, Black Widow, and Trypanosome are most closely related?
A: The Vampire Bat and King Cobra because they share Domain, Kingdom, and Phylum (both are vertebrates in the Phylum Chordata).
Q: Why was DNA evidence needed to resolve the three domains?
A: Bacteria and Archaea lack enough distinct morphological characteristics to differentiate them; DNA revealed Archaea are more closely related to Eukarya than to Bacteria.