Abiogenesis The spontaneous generation of life from non-living matter. It was widely held that maggots arose spontaneously in rotting meat or broth.

Francesco Redi (Italian 1668) One of the first to disprove spontaneous generation. An Italian doctor who proved maggots came from flies.

Lazzaro Spallanzani Some scientists believed that there was a life force in the air He tried to disprove the life force theory He was unsuccessful There are microorganism in the air

Louis Pasteur Successful in proving there was no life force The curved neck allowed air to pass but trapped microorganisms

But how did life first form? Biogenesis All living things arise from other living things But how did life first form?

RNA Theory The first molecules of life were RNA RNA Carried genetic information Can be replicated Can make proteins Is a catalyst Similar in form to ATP RNA evolved into DNA

Oparin (1930) Spontaneous generation did occur once at the beginning of life Believed that at high temperatures and with electrical charge the early gases could combine to form simple organic compounds As the Earth cooled the organic compounds collected in the oceans = Primordial soup

Miller & Urey (1953) Tested Oparin’s Hypothesis under laboratory conditions and produced some amino acids and sugars

Alternative Theory Metorites may have brought organic compounds (amino acids) to Earth

First Cells They were: Prokaryotic Anaerobic Herterotrophic

Endosymbiotic Theory Lynn Margulis Evolution of eukaryotic cells Eukaryotic cells evolved from large prokaryotic cells that were invaded by small aerobic and small photosynthetic prokaryotes

LaMarck Lamark said organisms acquired traits by using their bodies in new ways These new characteristics were passed to offspring Lamark was totally wrong!

Decent with Modification (Change in Species Over Time) Evolution Decent with Modification (Change in Species Over Time)

Mechanisms for Evolution Natural Selection Environmental Pressures Variation Competition Isolation Sexual Selection

Sexual Selection Sexual Selection Variation Competition for mates Choice

Charles Darwin As a result of his travels to the Galapagos islands and extensive studies of various organisms He developed 2 major theories Decent with modification Modification by natural selection

Rules for Natural Selection 1. Organisms differ; variation is inherited 2. Organisms produce more offspring than survive 3. Organisms compete for resources 4. Organisms with advantages survive to pass those advantages to their children 5. Species alive today are descended with modifications from common ancestors

Natural Selection

Methods of Natural Selection Stabilizing – Favors the average form of a trait Directional – Favors the extreme form of a trait Disruptive – Favors both extremes

Antibiotic Resistance

Speciation Geographic isolation Reproductive isolation Geographic barrier between populations Reproductive isolation Pre-zygote – No breeding Different mating seasons Not recognizing an organism as a potential mate Post-zygote – Fertilization Offspring are sterile or no zygote is formed

Evidence for Evolution Fossil record Homologous body structures Embryology Geographic distribution Biochemical evidence (Genetic)

Fossil Record The fossil record infers the history of the Earth Shows new life forms have arisen during the Earth’s history Shows diversity in the life forms

Relative Dating Vs. Radioactivity Where fossils are located in the strata Not as accurate Uses the degradation of radioactive elements Example: Carbon Dating More accurate

Homologous Body Structures Structures look similar but function differently

Vestigial Organs Organ that serves no useful function e.g. Appendix, tailbone, Wisdom teeth

Embryology Similarities in Embryology In their early stages of development, chickens, turtles and rats look similar, providing evidence that they shared a common ancestry.

Geographic Distribution

Biochemical Evidence Genetic material in all organisms is similar Shows a common ancestor for all living things DNA

Pace of Evolution Gradualism – Slow and steady change over time Punctuated Equilibrium – abrupt change followed by little or no change