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.