Fossils Ancient and extinct species Not complete – Conditions are rare What can become a fossil? – Hard parts most likely – Entire organisms – Part of organisms – Embryos – Footprints – Burrows – Scat

What can we learn from fossils? Body structures – Evolutionary relationships Movement of animals Climate

Relative Dating Lower layers are older Look at what layer the fossil is in Works locally

Radiometric Dating Determine actual age Uses breakdown of radioactive elements – Consistent rate of decay – Half-life Recent fossils – Carbon-14 dating – Process of using – Fossil needs to Have been alive Less than 60,000 yrs. old

Older fossils – More than 60,000 yrs. – Use rock layer – Use other elements K U – Age of rock = age of fossil

Early History of Earth Formation – 4.5 billion years ago Bombarded 3.9 billion yrs. – Oceans formed Brown color – Atmosphere Composition Color

First Organic Molecules Miller and Urey – Simulated early environment – Produced amino acids – Current research Microspheres – million yrs – Cooler and liquid water – Fossil bacteria? – Bubbles of organic molecules – Selectively permeable membranes – Stored, released energy

RNA and DNA – Unknown origin – RNA first Production of oxygen – Fossil prokaryotes 3.5 billion yrs. Anaerobic – Photosynthetic bacteria 2.2 billion yrs. Formed rust – Oxygen in atmosphere Formed ozone Took several million yrs. Toxic to bacteria

Daily Review #1 1.Describe the difference between relative and absolute dating. 2.What has the Miller Urey experiment and microspheres told us about early life on Earth? 3.What was the early Earth like? 4.What can fossils tell us about life on Earth?

Origin of Eukaryotic Cell Endosymbiotic theory – Prokaryotic cell membranes – Lived inside other cells – Mitochondria – Chloroplasts Modern evidence – Lynn Margulis – DNA – Ribosomes – Reproduction Sexual reproduction

Lesson Overview Lesson Overview Genes and Variation Darwin and Mendel –Data available –Connection not made Genetics and natural selection –Works on phenotype –Higher fitness phenotype survives –Acts on entire organism

Lesson Overview Lesson Overview Genes and Variation Populations Research on allele frequency Gene pool Relative frequency Evidence of evolution –Change in relative frequency

Lesson Overview Lesson Overview Genes and Variation # of phenotypes depends on genes Single-gene trait –# of phenotypes –Example Polygenic trait –# of genes –Phenotypes –Example –Creates a normal distribution curve

Lesson Overview Lesson Overview Genes and Variation Single-Gene Traits Leads to changes Lizards –Single-gene trait –Normal, mutations –Red lizards –Black lizards –Change in phenotypes

Lesson Overview Lesson Overview Genes and Variation Polygenic Traits More complex Directional selection Stabilizing selection Disruptive selection

Lesson Overview Lesson Overview Genes and Variation

Lesson Overview Lesson Overview Genes and Variation Speciation Definition Species Isolating mechanisms –Interbreeding stops –Genes don’t spread –Reproductively isolated –Form separate species

Lesson Overview Lesson Overview Genes and Variation Behavioral isolation –Rituals Geographic isolation –Geographic barrier Temporal isolation –Reproductive timing Speciation video video