Evolution

Fossils

• Found in sedimentary rock• Organism preserved in rock before

decay• Types:

• Imprint• Mold• Cast• Petrified

Imprint Fossil

Mold Fossil

Cast Fossil

Petrified Fossil

Dating• Relative Dating: determining age in

relation to other fossils

• Absolute Dating: using radioactive particles to find an estimated age of rock/organism

• Radioactive Isotope: atom with unstable number of neutrons; unstable atoms change into more stable atoms over time

Relative Dating

Absolute Dating

History of EvolutionEvolution: How things change over time

1. Jean Baptiste de Lamarko Inheritance of acquired characteristicso Use and disuse (Ex. Giraffes)

2. Alfred Russel Wallaceo Same arguments/conclusions as Darwino Not credited with the theory of evolution

3. Charles Darwino Conclusion natural selection as a

mechanism for change

Artificial Selection

• Artificial Selection: human intervention in animal/plant reproduction (genetic engineering)

• Ex. Fruit/vegetable size, milk-producing cows, dog breeders

Darwin’s Theory of Evolutionby Natural Selection

1. Variations exist within populations • Finches and beak sizes, human height

2. Some variations are more advantageous for survival/reproduction• Peppered moths

http://www.biologycorner.com/worksheets/pepperedmoth.html

Darwin’s Theory of Evolutionby Natural Selection

3. Organisms produce more offspring than survive• Fish, frogs

4. Overtime, offspring of survivors make up a larger portion of populations• Those that die take poor traits with

them• SURVIVAL OF THE FITTEST!!

Natural Selection

• Acts on the phenotype of an organism

• With a change in environment a trait may become advantageous and organisms that have that trait are more likely to survive

Adaptations

• Variation in a population that provides an advantage in a specific environment

Types of Adaptations

1. Structural• Change in structure• Ex. Wings, lungs

2. Physiological• Internal adjustment (chemical change)• Ex. Adrenalin

3. Behavioral• Action • Ex. Survival instinct

Evidence of Evolution

1. Homologous Structures• Similar structure• Ex. Limb of salamander, lizard, turtle

2. Vestigial Structures• Body parts with no function• Ex. Human appendix, ear wiggling

muscles, wisdom teeth, hip bone in whale

Evidence of Evolution

1. Homologous Structures• Similar structure• Ex. Limb of salamander, lizard, turtle

2. Vestigial Structures• Body parts with no function• Ex. Human appendix

Evidence of Evolution

3. Analogous Structures• Similar function, different structure• Ex. Insect and bird wing

4. Embryonic Development• Gill slits and tails• DNA/amino acid comparison

Human beta chain 0

Gorilla 1

Gibbon 2

Rhesus monkey 8

Dog 15

Horse, cow 25

Mouse 27

Gray kangaroo 38

Chicken 45

Frog 67

Lamprey 125

Sea slug (a mollusk) 127Soybean

(leghemoglobin)124

Number of amino acids that are different than the human hemoglobin beta chain

Gill slits

tail

How Does Evolution Work?Two Theories:

1. Gradualism• Gradual change of species over time • Fossil record supports this theory

2. Punctuated Equilibrium• Step-like pattern in a series over a

period of time• Ex. Volcano eruption, meteor (change in

form was immediate)• Parts of fossil record support this

Natural Selection

• Acts on the phenotype of an organism

• Harmful, recessive allele takes long time to disappear

• With a change in environment a trait may become advantageous

Terms• Gene pool:

– all genes in a population• Allele:

– Alternate form of a gene (one of a pair)

– ex. brown and blue eye color• Allele frequency:

– percentage of a particular allele in the gene pool

Terms

• Species: – group of organisms that interbreed

and produce fertile offspring

Terms

• Genetic equilibrium: – allele frequency in a population

remains the same means that evolution is not occurring

• If allele frequency changes, genetic equilibrium altered and evolution is occurring

How does gene pool change?

1. Mutation2. Genetic drift3. Gene flow

Three Types of Natural Selection

1. Stabilizing Selection• Favors intermediate• ex. 20th century babies 8 lbs. survive

2. Directional Selection• Single extreme is selected for• ex. long-necked giraffes

3. Disruptive Selection• Extremes are selected for, intermediate

selected against• 2 separate populations have distinct

characteristics

Natural selection may result in a new species (speciation) if a permanent barrier prevents breeding between members of a species

Two Types of Genetic Isolation

1. Geographic Isolation• Physical barrier separates a population

into different groups

2. Reproductive Isolation• Species in the same area, cannot share

DNA due to differences in reproductiona) Seasonal b) Behavioral c) Mechanical d) Gametic

Trends in Evolution1. Divergent Evolution

• Related species become less alike because separated by barrier

2. Convergent Evolution• Unrelated species become similar

3. Parallel Evolution• 2 different species in two different

environments develop same type of adaptation due to similar selective pressure

Evidence for Evolution and Classification

1. Homologous Structures2. Analogous Structures3. Vestigial Structures4. DNA Relationships5. Embryonic Development6. Fossils7. Radioactive Dating

Taxonomy

• Science of classifying organisms• Carolous Linnaeus = father of binomial

nomenclature• Binomial Nomenclature = latin, 2 names• Ex. Homo sapiens (Genus species)

• Ursus horribulus (grizzly bear)• Ursus americanus (American black bear)• Turdus migratorius (Robin)

Naming System (General Specific)

• Kingdom…..Animalia• Phylum……Chordata• Class………Mammalia• Order………Primates• Family…….Hominidaea• Genus……..Homo• Species……Sapiens

Kingdom Phylum Class Order Family Genus Species

• Kings Play Chess On Fine Glass Sets

• Kings Play Chess On Fuzzy Green Sofas

• King Philip Came Over From Germany Singing

• King Philip Crossed Over For Green Spaghetti

Kingdoms (5)

5 Characteristics Used to Classify Kingdoms

1. Complexity…• Prokaryotic vs. eukaryotic

2. Organization…• Unicellular vs. multicellular

3. Feeding…• Autotrophic vs. heterotrophic

4. Movement…• Sessile vs. motile

5. Reproduction…• Asexual vs. sexual

Classification

• Phylogenetic Tree: – shows evolutionary relationships– graphical representation of

relationships between organisms

• Dichotomous Key: – checkpoint used to classify organisms– Always have two choices