Spontaneous Generation – living things could come from nonliving things Biogenesis – all living things come from other living things

Francesco Redi – questioned the belief that flies were generated spontaneously from rotting meat Observation Tiny wormlike maggots turned into sturdy oval cases, from which flies eventually emerge Experimental Group – jars with nets over them that contained meat inside Netting allowed air to enter but not flies Control Group – uncovered jars with meat inside Result – maggots swarmed over the meat in the open jars while the experimental remained maggot free

Control Experimental A: Independent Variable - cork Experimental B: Independent Variable - net

Spallanzani Hypothesis – microorganisms form not from air but from other microorganisms Experiment – boiled broth in a flask to kill all microorganisms in it Experimental Group – boiled then sealed flask Control Group – boiled then left open Result – sealed flask remained clear and free of microorganisms; open flasks became cloudy *Disagreed – heated the flasks too long, killing the “vital force” in the air inside the flask

Louis Pasteur – Made a goose-neck flask that prevented solid particles from entering but allowed air – remained clear for up to a year – he broke the neck off & the broth became cloudy

Fossil – trace of a long dead organism Found in sedimentary rock – deposited by wind & water Develop from hard body parts Overtime hard minerals replace the tissue leaving rocklike structures Mold – imprint in the rock in the shape of the organism Cast – mold has been filled with hard minerals making a rocklike model

Distribution of Fossils Law of Superposition – successive layers of rock or soil were deposited on top of one another by wind or water Lowest stratum (rock layer) is the oldest Relative age – using law of superposition to figure out the age of one fossil compared to another

Early scientists proposed ideas about evolution. Evolution is biological change over time A species is a group of organisms that can reproduce and have fertile offspring.

10.2 Darwin’s Observations There were many important naturalists in the 18th century. Naturalist – collect specimens and keep careful records of observations Lamarck: Similar species descended from a common ancestor Acquired Trait – trait not determined by genes but by experience or behavior Believed acquired traits could be passed down

10.2 Darwin’s Observations Charles Darwin H.M.S. Beagle 5-year mapping and collecting expedition to South America and South Pacific

10.2 Darwin’s Observations Variation is a difference in a physical trait. Galápagos tortoises that live in areas with tall plants have long necks and legs. Galápagos finches that live in areas with hard-shelled nuts have strong beaks.

10.2 Darwin’s Observations An adaptation is a feature that allow an organism to better survive in its environment. Adaptations can lead to genetic change in a population. The change in genetic makeup of the population is evolution

10.2 Darwin’s Observations Darwin’s Theories Descent with Modification – newer forms appearing in the fossil record are actually the modified descendants of older species Natural Selection – Organisms with favorable traits survive, reproduce, and pass the variations to the next generation

10.3 Theory of Natural Selection 10.4 Evidence of Evolution 10.3 Theory of Natural Selection Artificial selection is the process by which humans select traits through breeding. neck feathers crop tail feathers

10.3 Theory of Natural Selection 10.4 Evidence of Evolution 10.3 Theory of Natural Selection The study of geography provides evidence of evolution. island species most closely resemble nearest mainland species populations can show variation from one island to another Biogeography - Study of the distribution of organisms around the world.

10.3 Theory of Natural Selection 10.4 Evidence of Evolution Embryology provides evidence of evolution. identical larvae, different adult body forms Similarites in Biochemistry: DNA, RNA, ATP. Etc Embryos of Vertebrates and gill slits? Larva Adult barnacle Adult crab

10.3 Theory of Natural Selection 10.4 Evidence of Evolution Anatomy provides evidence of evolution. Homologous structures are similar in structure but different in function. Human hand Bat wing Mole foot

10.3 Theory of Natural Selection 10.4 Evidence of Evolution The study of anatomy provides evidence of evolution. Analogous structures –similar function but different structure Human hand Bat wing Mole foot Fly wing

10.4 Evidence of Evolution 10.3 Theory of Natural Selection Vestigial structures are remnants of organs or structures that had a function in an early ancestor. Ostrich wings are examples of vestigial structures.

10.4 Evidence of Evolution Vestigial Structures

11.2 Natural Selection in Populations Natural selection can change the distribution of a trait in one of three ways. Normal Distribution – Frequency is highest near the mean value (average) and decreases toward each extreme end of the range.

11.2 Natural Selection in Populations 10.3 Theory of Natural Selection Stabilizing selection favors the intermediate (average) phenotype rather than either extremes.

11.2 Natural Selection in Populations 10.3 Theory of Natural Selection Directional selection favors phenotypes at one extreme.

11.2 Natural Selection in Populations 10.3 Theory of Natural Selection Disruptive selection favors both extreme phenotypes.

11.6 Patterns in Evolution 10.3 Theory of Natural Selection Convergent evolution – Evolution toward similar characteristics in unrelated species. Different species must adapt to similar environments. Ex: Aquatic organisms

10.3 Theory of Natural Selection 11.6 Patterns in Evolution 10.3 Theory of Natural Selection Divergent evolution – 2 or more related populations become more dissimilar. Response to differing habitats How do convergent and divergent evolution illustrate the directional nature of natural selection? ancestor red fox kit fox

11.6 Patterns in Evolution 10.3 Theory of Natural Selection Coevolution – change of 2 or more species in close association with each occur in beneficial and competitive relationships.

Species can become extinct. 11.6 Patterns in Evolution 10.3 Theory of Natural Selection Species can become extinct. Extinction is the elimination of a species from Earth.

11.6 Patterns in Evolution 10.3 Theory of Natural Selection Mass extinctions are rare but much more intense. destroy many species at global level thought to be caused by catastrophic events at least five mass extinctions in last 600 million years

11.6 Patterns in Evolution 10.4 Evidence of Evolution Adaptive radiation – The diversification of one ancestral species into many species. descendent species usually adapted to wide range of environments

Punctuated Equilibrium A repeating pattern in the history of life reflected in the fossil record shows bursts of evolutionary activity that are followed by long periods of stability.