Review: Evolution, Speciation, and Biodiversity (A3/4 Focus) PDF

Review: Evolution, Speciation, and Biodiversity (A3/4 Focus) A4.1.1: Evolution as Change in Heritable Characteristics Key Ideas: ○ Evolution refers to changes in the heritable characteristics of a population over generations. ○ Distinction between Lamarckism (...

Review: Evolution, Speciation, and Biodiversity (A3/4 Focus) A4.1.1: Evolution as Change in Heritable Characteristics Key Ideas: ○ Evolution refers to changes in the heritable characteristics of a population over generations. ○ Distinction between Lamarckism (inheritance of acquired traits) and Darwinian evolution (natural selection). ○ The paradigm shift: evolution by natural selection transformed biology into a field grounded in evidence-based theory. Questions: 1. Define evolution and explain how it differs from Lamarckism. 2. Why was Darwin's theory of natural selection considered a paradigm shift in biology? A4.1.2: Molecular Evidence for Evolution Key Ideas: ○ DNA, RNA, and protein sequence similarities and differences provide evidence for evolutionary relationships. ○ The more similar the sequences, the more closely related the species are, and vice versa. ○ Sequence divergence over time correlates with evolutionary distances. Questions: 1. How do differences in amino acid sequences between two species provide evidence of their evolutionary relationship? 2. Explain the relationship between evolutionary time and sequence similarity in DNA or proteins. A4.1.3: Evidence from Artificial Selection Key Ideas: ○ Artificial selection is the process by which humans breed organisms for desirable traits.  ○ Examples include selective breeding of crops for yield or animals for specific traits (e.g., docility in dogs). ○ Artificial selection demonstrates how rapid evolutionary change can occur under directed pressures. Questions: 1. Define artificial selection and explain its role in demonstrating evolution. 2. Provide one example of artificial selection in plants and one in animals, explaining the evolutionary changes that occurred. A4.1.4: Homologous Structures and Divergent Evolution Key Ideas: ○ Homologous structures (e.g., pentadactyl limbs) indicate common ancestry but have evolved for different functions due to divergent evolution. ○ Pentadactyl limb bones are structured similarly across amphibians, reptiles, birds, and mammals but functionally adapted. Questions: 1. What is a homologous structure, and how does it differ from an analogous structure? 2. How does the pentadactyl limb exemplify divergent evolution? A4.1.5: Convergent Evolution and Analogous Structures Key Ideas: ○ Analogous structures arise through convergent evolution, where unrelated species evolve similar traits to adapt to similar environments. ○ Example: wings of bats (mammals) and insects (arthropods). Questions: 1. Define analogous structures and give an example. 2. Explain how cladograms can be used to determine whether traits are homologous or analogous. A4.1.6 to A4.1.8: Speciation and Reproductive Isolation Key Ideas:  ○ Speciation occurs when populations of a species split and diverge due to reproductive isolation (geographic, temporal, or behavioral). ○ Allopatric speciation involves geographic separation, while sympatric speciation occurs within overlapping ranges. ○ Examples: Bonobos and chimpanzees (geographic isolation). Questions: 1. Compare allopatric and sympatric speciation, giving an example of each. 2. Describe the role of reproductive isolation in the divergence of bonobos and chimpanzees. A4.1.9 to A4.1.11: Biodiversity and Hybridization Key Ideas: ○ Adaptive radiation creates biodiversity by allowing species to exploit vacant niches. ○ Barriers to hybridization (e.g., pre-zygotic and post-zygotic) prevent gene mixing between species. ○ Hybrid species like mules are sterile, maintaining species boundaries. Questions: 1. How does adaptive radiation increase biodiversity? Provide an example. 2. Differentiate between pre-zygotic and post-zygotic mechanisms of hybridization prevention. A4.2.1 to A4.2.5: Biodiversity and Extinction Key Ideas: ○ Biodiversity includes variety at all biological levels: species, genetic, and ecosystem. ○ Past biodiversity levels (e.g., before mass extinctions) were higher than current levels. ○ Anthropogenic causes like habitat destruction, pollution, and climate change threaten biodiversity (e.g., Caribbean monk seal extinction). ○ Evidence of a biodiversity crisis includes declining species richness and ecosystem health. Questions:  1. Define biodiversity and outline how it is quantified at different levels of biological organization. 2. Compare past biodiversity levels to current levels and discuss the impact of human activities on biodiversity. A4.2.6 to A4.2.8: Biodiversity Conservation Key Ideas: ○ Conservation efforts include in situ methods (e.g., wildlife reserves) and ex situ methods (e.g., zoos, seed banks). ○ The EDGE program prioritizes evolutionarily distinct and globally endangered species. ○ Rewilding, or restoring ecosystems to their natural state, is an emerging conservation strategy. Questions: 1. Compare in situ and ex situ conservation methods, giving examples of each. 2. Explain the rationale behind the EDGE of Existence program and its prioritization criteria. Integration Across Topics Connections: ○ Evolutionary principles (A4) underpin biodiversity (A4.2) by explaining the origins and loss of species diversity. ○ Molecular evidence (A4.1.2) supports phylogenetic relationships discussed in classification (A3). ○ Human impacts on biodiversity (A4.2.6) link to ecological concepts like energy flow and sustainability (A1). Cumulative Questions: 1. How does the theory of evolution explain patterns of biodiversity observed today? 2. Discuss the impact of human activities on speciation, extinction, and overall biodiversity. 3. Why is it essential to integrate conservation methods like rewilding and the EDGE program in addressing the biodiversity crisis? A3.1.1: Variation as a Defining Feature of Life Key Ideas: ○ Organisms: Living entities with shared biological processes.  ○ Variation: Differences within and between organisms due to genetic and environmental factors. ○ Sources of Genetic Variation: Mutations, sexual reproduction (crossing over, independent assortment, random fertilization). ○ Discrete Variation: Distinct categories (e.g., blood type). ○ Continuous Variation: Range of phenotypes (e.g., height). ○ Compare Variation: Differences within species arise from shared genetics; differences between species reflect divergent evolution. Questions: 1. Define organism and variation. List two sources of genetic variation. 2. Compare discrete variation to continuous variation and give examples of each. A3.1.2 to A3.1.5: Species and Speciation Key Ideas: ○ Morphological Species Concept: Groups of organisms with shared physical traits. ○ Binomial Nomenclature: Scientific naming system with standardized rules (e.g., genus capitalized, species lowercase, italicized or underlined). ○ Biological Species Concept: Species are groups that interbreed and produce fertile offspring. ○ Speciation: Formation of new species due to reproductive isolation. Questions: 1. Define species using the biological species concept and explain one limitation of this definition. 2. Outline the difficulties in distinguishing between populations and species during speciation. A3.1.6 to A3.1.7: Chromosome Numbers and Karyotyping Key Ideas: ○ Chromosome number distinguishes species (humans: 46; chimpanzees: 48). ○ Karyotype: Chromosome arrangement by size, banding patterns, and centromere position. ○ Karyogram: Visual representation of a karyotype. ○ Human sex determination: XX (female) or XY (male). Questions: 1. State why diploid chromosome numbers are typically even.  2. Deduce the sex of an individual based on a karyogram. A3.1.8 to A3.1.11: Genomes and Sequencing Key Ideas: ○ Genome: Entire genetic material of an organism. ○ Gene: Unit of heredity; Allele: Variant of a gene. ○ Genome size does not correlate with organism complexity. ○ Applications of genome sequencing: Medicine, agriculture, evolutionary studies. ○ Ethical considerations: Privacy, discrimination, and access to genetic information. Questions: 1. Define genome, gene, and allele. 2. Discuss one ethical consideration of genome sequencing. AHL A3.1.12 to A3.1.15: Advanced Concepts in Species Identification Key Ideas: ○ Horizontal Gene Transfer: Genetic exchange between species (common in bacteria). ○ DNA Barcoding: Identifying species from environmental DNA (e.g., conservation, tracking biodiversity). ○ Dichotomous Key: Tool for species identification based on step-by-step traits. Questions: 1. Explain how horizontal gene transfer complicates applying the biological species concept to bacteria. 2. Outline one application of DNA barcoding for environmental DNA. A3.2.1: Need for Classification Key Ideas: ○ Taxonomy: Science of classification. ○ Traditional Hierarchy: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species. ○ Benefits: Simplifies study, shows relationships, organizes biodiversity. Key Question: List the levels of the traditional classification hierarchy and state one benefit of classification. A3.2.2–A3.2.4: Modern Challenges and Evolutionary Relationships Key Ideas: ○ Limitations: Some organisms don't fit neatly due to convergent evolution or genetic divergence. ○ Clade: Group of organisms with a common ancestor; identified on cladograms using molecular and physical evidence. Key Question: Define a clade and outline one difficulty in the traditional classification system. A3.2.5–A3.2.7: Cladograms and Molecular Evidence Key Ideas: ○ Molecular Clock: Sequence differences in DNA/proteins estimate divergence time. ○ Cladograms: Show evolutionary relationships using parsimony and bioinformatics. Key Question: Explain how DNA sequences are used to construct cladograms. A3.2.8–A3.2.9: Reclassification and Domains of Life Key Ideas: ○ Cladistics: Reclassification based on molecular data (e.g., rRNA). ○ Three Domains: Archaea, Bacteria, Eukarya. Key Question: List the three domains of life and explain the role of rRNA in their classification.