Evolution • Fossil Records • Remains or traces of organisms that lived in the past • Usually found in sedimentary rocks
Evolution • Organism buried soon after death and the hard parts become fossilized • Fossils indicate a great deal about the actual structure of the organisms and their environment
Evolution • Types of Fossils • petrified bones • imprints • molds • preserved in tar, amber, or ice
Evolution • Dating of fossils • Layering of fossils • Older fossils are found in the lower levels of sediment • Carbon-14 Dating • Carbon-14 is a radioactive isotope in all living organisms. • It decays at a known rate • Carbon-12 does not decay • Compare ratio of C-12 to C-14 to determine age
Evolution • Contemporary changes • DDT resistance in insects • Antibiotic resistance in bacteria • Indirect Evidences • Evidences of common ancestry • Parts of the body with similar (homologous) structures
Evolution • Indirect Evidences • Similar patterns of inheritance • Biochemical Similarities (protein and DNA) • Vestigial organs
The Methods of Change • Lamarck’s Theory – 1809 • “Inner need” to change • Inheritance of acquired characteristics (based on use and disuse) • Disproved
The Methods of Change • Charles Darwin and Natural Selection - (1859) • Naturalist on HMS Beagle • Exploration of South America (3 ½ years) • Visited the Galapagos Islands
The Methods of Change • Natural Selection • Living things increase in number geometrically - (overproduction) • There is no net increase in the number of individuals over a long period of time • A “struggle for existence” exists since not all individuals can survive
The Methods of Change • Natural Selection • No two individuals are exactly alike (variation) • In the struggle for existence those variations which are better adapted to their environment leave behind them proportionately more offspring than those less adapted - (Survival of the Fittest)
The Methods of Change • A Modern Perspective • Mutation • A sudden change in the genetic material (A source of variation) • Recombination of genes within a population • Provides new combinations for natural selection • Shows how the percentage of genes in a population can change
The Methods of Change • A Modern Perspective • Isolation • Separation of a population from others of the same kind • Natural Selection • Certain traits give an adaptive advantage to organisms and they leave more offspring
Species • A group of individuals that LOOK similar and are capable of producing FERTILE offspring in the natural environment.
Population • All of the members of the same SPECIES that live in particular AREA at the same TIME.
Variation in a population • Bell Curve • The distribution of traits (Average is the middle.) • Mode • The number that occurs most often (High pt.) • Range • The lowest number to the highest number
Gene Pool • The collection of GENES for all of the traits in a POPULATION
Hardy-Weinberg Principle • Genetic Equilibrium • No CHANGE in the gene pool
Conditions that must exist for genetic equilibrium 1. No MUTATION 2. No MIGRATION 3. Large POPULATION 4. Random MATING 5. No NATURAL SELECTION
Natural Selection Four types of selection 1. Stabilizing Selection 2. Directional Selection 3. Disruptive Selection 4. Sexual Selection
Stabilizing Selection • Individuals with the AVERAGE form have the ADVANTAGE
Directional Selection • Individuals with one of the EXTREME forms have the ADVANTAGE
Disruptive Selection • Individuals with either of the EXTREME forms have the ADVANTAGE
Sexual Selection • Preferential choice of a MATEbased on the presence of a specific trait
Speciation • The formation of new SPECIES
Isolation • Separation of a formerly successful BREEDING population
Geographic Isolation • Separated PHYSICALLY from each other
Reproductive Isolation • Can no longer produce FERTILE offspring
Extinction • When an entire SPECIES dies off.
