- Important contributors to the progression of scientific thought & their contributions: - Hutton Principle of Uniformitarianism - Lyell Geological features are the result of small changes over a long time - Kelvin Cooling experiments indicate greater antiquity of Earth - Linnaeus Binomial taxonomy - Cuvier Introduction of comparative anatomy & Catastrophism - Lamarck First theory of evolution & acquisition of inherited features - Malthus Resource competition & the struggle for survival - Darwin The Origin of Species and evolution by natural selection - De Perthes Great antiquity of humanity based on stone artefacts - Wallace Independently developed idea of natural selection - Natural selection: - 5 theories of evolution: - Species change - All organisms share a common ancestry - Evolution is gradual - Evolution leads to speciation - Evolution occurs through Natural Selection - The 3 necessary & sufficient conditions for evolution by natural selection: - Variation in a trait - Genetic inheritance of the trait - Differential reproductive success - The 3 modes of natural selection: - Stabilizing selection - Directional selection - Disruptive selection - Focus on populations instead of individuals - Natural selection cannot be goal oriented - Natural selection optimizes long term reproductive success instead of maximizing short term reproductive success. This demonstrates that there are no perfect adaptations. Instead, adaptations are almost always the result of a trade-off between costs and benefits. Examples of such trade-offs are found in both Resource Defense Polygyny and Female-Defense Polygyny. - Incorrect interpretation of the tenets of natural selection results in: - Evolution = progress - Natural selection favors those individuals that are stronger/better/fitter - Naturalistic fallacy - Genetics: - Mitosis & Meiosis - Mitosis: somatic cells & diploid - Meiosis: sex cells & haploid - Crossover (“recombination”) occurs during meiosis and is the exchange of genetic material between homologous chromosomes. Crossover produces new combinations of alleles by reshuffling the genetic material. - Terminology - Gene vs. locus vs. allele - Genotype vs. phenotype - Heterozygous vs. homozygous - Dominant vs. recessive vs. codominant - Mendelian inheritance: - Observed characteristics are determined by genes & alleles - Expression of genes in the individual is dependent on whether the allele is dominant, recessive, or codominant - During fertilization, alleles from both parents are joined to form a pair.- Each gene is equally likely to be transmitted - Genes that code for different traits assort independently of each other - Mutation: - Defined as a change in DNA - Mutations are the only source of new variation Mutations are predominantly neutral or negative - Mechanisms of Evolution - Evolution is a change in allele frequencies in a population over generations - Mechanisms of Evolution: - Random mechanisms: - Mutation - Gene flow - Genetic drift - Non-random mechanisms - Natural selection - Random mechanisms of evolution can lead to evolution but does not produce adaptations - Speciation - Speciation bridges micro- and macro-evolution - Micro-evolution occurs through the four mechanism of evolution - Macro-evolution is the process of speciation above the species-level - Speciation is a process instead of an event - Speciation occurs through reproductive isolation, which occurs through: - Mate choice - Mating mechanisms - Separation in time, space, and social behavior - Species concepts: - Biological Species Concept - Ecological Species Concept - Species Mate Recognition Concept - Types of speciation - Allopatric speciation – geographic isolation - Parapatric speciation - Sympatric speciation - Phylogeny - Homology (ancestry) & convergence (analogy) - Proper assessment is dependent on the scale at which it is examined - Cladistic relationships between organisms are best studied using shared, derived traits - Phylogeny: the evolutionary history of groups - Grades vs. clades: - Grades: taxon united by a level of morphological complexity - Clades: group consisting of its species and all of its descendants - Human Adaptation & Variation - Many traits are influenced by both genes and other factors - Heritability: proportion of variance in a trait explained by genetic factors - Norm of Reaction: genetically identical individuals express traits differently in different environments - Race vs. population - Although humans vary across space in ways that cannot be meaningfully classified into different ‘races’, human populations vary in time and space in ways that (1) represent genetic adaptations to local conditions and/or (2) reflect different environments (e.g. literacy, healthcare,