Test 1-Bio

BIOL 1407 Review Notes

Chapter 23 – Evolution of Populations

1. Term Used by Darwin: Darwin referred to evolution in the context of "descent with modification," implying the gradual change of species over time.

2. Natural Selection: A process in which individuals with favorable traits are more likely to survive and reproduce. a. Traits Natural Selection Acts On: Traits that affect survival and reproduction, often inherited characteristics beneficial to the organism's environment.

3. Sources of Genetic Variation:

   • Mutations: Changes in DNA sequence that can create new alleles.

   • Gene Flow: Movement of alleles between populations through migration.

   • Genetic Drift: Random changes in allele frequencies, especially in small populations.

   • Sexual Reproduction: Mixing of parental genes during gamete formation and fertilization enhances genetic diversity.

4. Hardy-Weinberg Principle: a. Description: A principle stating that allele and genotype frequencies in a population remain constant from generation to generation in the absence of evolutionary influences. b. Assumptions: Large population size, no mutations, no gene flow, random mating, and no natural selection. c. Equation for Allele Frequency: p + q = 1 d. Equation for Genotypic Frequency: p² + 2pq + q² = 1 e. Letter Representation: p = frequency of dominant allele; q = frequency of recessive allele. f. Determining Evolution: If observed frequencies differ from expected frequencies, the population may be evolving. g. Basic Problem-Solving: Calculate frequencies using the Hardy-Weinberg equations to assess if a population is evolving.

5. Mechanisms of Population Change: a. Natural Selection: Favors advantageous traits, affecting allele frequencies. b. Genetic Drift: Random changes in populations that can lead to significant fluctuations in allele frequencies. c. Types of Genetic Drift: Bottleneck effect (population reduced drastically) and founder effect (a small group establishes a new population). d. Gene Flow: Introduction or removal of alleles due to migration, which can change allele frequencies.

6. Misleading Statements: “Struggle for existence” suggests direct competition; “survival of the fittest” is often misinterpreted as strength rather than reproductive success.

7. Relative Fitness: The contribution an individual makes to the gene pool relative to others; differs from everyday fitness, which refers to physical well-being.

8. Types of Selection: Directional, disruptive, and stabilizing selection.

9. Sexual Selection: A form of natural selection related to mate choice, often leading to sexual dimorphism.

10. Balancing Selection: Maintains genetic diversity in a population.

11. Natural Selection Limitations: It does not produce perfect organisms due to constraints like genetic variation, environmental changes, and historical factors.

12. Microevolution: Minor changes in allele frequencies within a population over time.

Chapter 24 – Speciation

1. Speciation: The process through which new species arise.

2. Species Concepts: Biological (species based on reproduction), morphological (based on physical characteristics), and phylogenetic (based on evolutionary history). Problems include hybrid species and cryptic species.

3. Geographical Variation: a. Ring Species: Species that are connected by a series of geographically adjacent populations that can interbreed. b. Clinal Variation: Gradual change in a trait or character over a geographical area.

4. Reproductive Isolating Mechanisms: a. Prezygotic vs. Postzygotic: Prezygotic prevents mating or fertilization, while postzygotic occurs after fertilization. b. Examples: Temporal isolation (prezygotic) and hybrid inviability (postzygotic).

5. Allopatric Speciation: Speciation due to geographical separation; example includes Darwin’s finches.

6. Sympatric Speciation: Speciation occurring in the same geographic area; example of polyploidy in plants.

7. Secondary Contact: When two separated populations are reunited; possible outcomes include: i. Reinforcement: Strengthened reproductive barriers. ii. Fusion: Two species merge into one. iii. Stability: Hybrid zones remain stable over time.

Chapter 25 – The History of Life on Earth

1. Macroevolution: Large-scale evolutionary changes over geological time.

2. Simple Cells Experiment: Miller-Urey experiment demonstrating the possible origins of life from abiotic conditions.

3. Environmental Alterations: a. Continental Drift: Changes habitats and biodiversity. b. Glacial Events: Affects sea levels and climate. c. Volcanic Eruptions: Causes mass disturbances in ecosystems.

4. Fossil Information: a. Formation: Most fossils form in sedimentary rock. b. Structures: Hard parts like bones and shells often fossilize. c. Soft-bodied Fossilization: Organisms may get trapped in amber or anoxic environments. d. Incomplete Record: Bias due to specific conditions required for fossilization. e. Relative Age: Determined through stratigraphy. f. Absolute Age: Found via radiometric dating. g. Information from Fossils: Direct (presence) and indirect (environmental conditions).

5. Endosymbiont Theory: Explains the origin of mitochondria and chloroplasts from free-living bacteria.

6. Extinction: a. Background Extinction: Normal rate of species loss. b. Mass Extinction: Large-scale, rapid loss of species. c. Worst Mass Extinction: The Permian-Triassic extinction, triggered by volcanic activity.

7. Survival Traits: High reproductive rates, adaptability, and diverse diets can aid survival.

8. Adaptive Radiation: Rapid diversification of species to fill different ecological niches.

9. Relation of Evolutionary Concepts: Microevolution leads to speciation, which contributes to macroevolution in terms of broader biodiversity changes.

Chapters 55-57 – Ecosystems and Biodiversity

1. Ecology: The study of interactions among organisms and their environment.

2. Definitions: a. Ecosystem: A community of living organisms and their physical environment. b. Community: All populations of different species living in a specific area. c. Population: Group of individuals of the same species. d. Organism: Individual living entity.

3. Range of Tolerance: The limits within which an organism can survive.

4. Limiting Factor Purpose: Constraints on population sizes/health. a. Land Limiting Factors: Water, nutrients, sunlight. b. Water Limiting Factors: Salinity, temperature, oxygen.

5. Food Chain/Web Components: Producers, consumers, decomposers.

6. Harm Factors of Substances: a. Solubility: Determines how substances interact in environments. b. Persistence: Length of time substances remain unchanged. c. Bioaccumulation: Accumulation of substances in an organism over time. d. Biomagnification: Increase in concentration of substances as one moves up the food chain. e. Chemical Interactions: Combined effects of multiple substances.

7. Nutrient Cycle Drivers: Autotrophs and decomposers; human impacts include CO2 increases and water use.

8. Climate Influencers: Latitude, elevation, proximity to water.

9. Biomes Recognitions: a. Tropical Forest: High biodiversity and rainfall. b. Savanna/Tropical Grassland: Grasslands with scattered trees; seasonal rainfall. c. Desert: Extremely low precipitation. d. Chaparral: Hot, dry summers; mild, wet winters. e. Temperate Grassland: Moderate rainfall and droughts. f. Temperate Deciduous Forest: Trees that shed leaves; seasonal temperatures. g. Coniferous Forest: Dominated by conifer trees; cooler climates. h. Temperate Rain Forest: High rainfall; diverse ecosystems. i. Tundra: Cold, treeless; permafrost.

10. Aquatic Life Zones Division: Pelagic, benthic, and intertidal zones.

11. Saltwater Life Zones: a. Major Zone: The continental shelf supports the most marine life. b. Human Impacts: Overfishing, pollution, climate change.

12. Freshwater Life Zones: a. Standing Water Term: Lentic. b. Moving Water Term: Lotic. c. Inland Wetlands Use: Water filtration, flood protection, wildlife habitat.

13. Biodiversity: The variety of life in a particular habitat or ecosystem.

14. Endangered Species: Species at risk of extinction. a. Characteristics: Low population numbers, specialized habitats.

15. Species Decline Factors: a. Habitat loss, hunting, pest control, trade, invasive species, pollution, climate change.

16. Concerns about Species Loss: Ecosystem stability, potential loss of resources, and loss of genetic diversity.

17. Conservation Techniques: a. Habitat Preservation: Protecting natural habitats. b. Habitat Restoration: Rehabilitating degraded habitats to a natural state.