evolution fossil records remains or traces of organisms that lived in the past usually found in...
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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 MIGRATION3. Large POPULATION 4. Random MATING 5. No NATURAL SELECTION
Natural Selection
Four types of selection1. Stabilizing Selection2. Directional Selection3. Disruptive Selection4. 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 MATE based 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.