Lecture Notes

Plant Tropisms and Adventitious Roots

• Adventitious Roots: Originate from the stem or other structures, not from the root system.
• Metatropism: Change in position of growth in plants, related to tropisms.

Darwin's Finches and Adaptive Radiation

• Different beak sizes in Galapagos finches.
• Example of adaptive radiation: Evolution from a common ancestor into diverse species.

Genetic Changes and Mutations

• Transposable Elements: Large genetic elements that cause genetic changes, excluding point mutations.
  • Minimum size: Several hundred bases.
• Point Mutations: Small genetic changes, a single base change.
• Third Codon Position (Wobble Base): Redundancy here minimizes translation errors.

Genome Coding

• Small percentage of the genome codes for proteins.
• Gene Families: Groups of related genes from ancestral gene specializations.
• Retro Elements: Transposable elements containing reverse transcriptase gene.

Maternal Effect

• Desert Locusts: Crowded mothers produce darker offspring.
• Example of a maternal effect.

Genetic and Evolutionary Concepts

• Genotype: Genetic constitution of an individual.
• Histone Changes: Affect gene expression by modifying chromatin structure.
• Hardy-Weinberg Equilibrium: Conditions and assumptions for genetic stability in populations.
• Heterozygote Advantage: Increased frequency of certain alleles due to natural selection.

Natural Selection and Evolutionary Fitness

• Natural selection affects fitness differences among biological entities.
• Pre-adaptation: Traits initially serve one purpose and later become beneficial for another.
• Kin Selection: Explains altruistic behavior based on genetic relatedness.

Selection Types

• Individual Selection: E.g., sexual selection in birds with long-tailed feathers.
• Group Selection: Requires groups of altruistic individuals.
• Speciation: Formation of new species affects evolutionary pathways.
• Exaptation: Traits are co-opted for new uses, like bird wings for swimming.

Genetic Concepts and Selection Coefficients

• Fitness Definition: Average lifetime contribution of an individual to the population.
• Relative Fitness: Represented by selection coefficients.

Mutation and Allele Frequency

• Not all components of fitness involve mutations.
• Allele Frequency Calculation: Based on genotype frequencies.
• Evolution by natural selection explains complex adaptations due to heritable differences.

Epistasis and Linkage Disequilibrium

• Epistasis: Interaction between alleles at different loci.
• Linkage Disequilibrium: Non-random association of alleles at different loci.

Exam Review and Specific Concepts

• Specific examples related to genetic changes and allele frequencies.
• Concepts such as Hardy-Weinberg and evolutionary processes.